Full Form: Albumin/Globulin Ratio
Alternative Names: A/G Ratio, Serum Albumin to Globulin Ratio, Albumin-Globulin Ratio, Alb/Glob Ratio, A/G Ratio, Total Protein with A/G Ratio
Category: Biochemistry / Liver & Kidney Function Test

Purpose:

Evaluates the balance between albumin and globulin proteins in the blood to assess liver function, kidney disease, and immune disorders.

The total protein level and the albumin-to-globulin (A/G) ratio determine the amount of protein in the blood. The body uses protein for various essential functions, such as energy production, muscle repair, and strengthening the immune system. The amount of protein in the blood is determined by a total protein level. Excess or deficiency of protein can be a sign of liver or kidney disease, infection, inflammation, malnutrition, and cancer.

Commonly Ordered For:

• Chronic liver disease (cirrhosis, hepatitis)
• Kidney disease (nephrotic syndrome)
• Nutritional status assessment
• Autoimmune or immune system disorders

Typical Normal Range:

• A/G Ratio: 1.0 – 2.1 (may vary slightly by lab)

Related Tests: Total Protein, Albumin, Globulin, Liver Function Tests (LFTs), Comprehensive Metabolic Panel (CMP), Kidney Function Tests, Protein Electrophoresis, Immunoglobulins (IgG, IgA, IgM, IgE) Studies

Notes:
A low A/G ratio may indicate chronic illness, liver disease, or autoimmune disorder; a high ratio may suggest genetic conditions or decreased globulin production.

Full Form: Alpha-1 Antitrypsin
Alternative Names: Alpha-1 Antitrypsin Test, Serum AAT Test, AAT Level Test, AAT Deficiency Test, Alpha-1 Protease Inhibitor Test, A1AT Test, AATD Test, α1-Antitrypsin
Category: Biochemistry / Genetic & Liver Function Test

Purpose:

Alpha-1 antitrypsin (A1AT or A1A), a protein produced by the liver, protects the lungs against harm brought on by inflammation. Its absence can lead to emphysema and early liver damage. This test measures alpha-1 antitrypsin, a protein that protects tissues from enzymatic damage. It is diagnosed with alpha-1 antitrypsin deficiency, which can lead to lung and liver problems.

Commonly Ordered For:

• Early-onset emphysema or COPD
• Unexplained chronic liver disease
• Family history of Alpha-1 Antitrypsin Deficiency
• Evaluation of neonatal jaundice or hepatitis

Typical Normal Range:

Serum: 100 – 300 mg/dL (may vary by lab)

Related Tests: Liver Function Tests (LFTs), Pulmonary Function Tests (PFTs), Genetic Testing for AAT mutations, Chest X-ray / CT Scan, Liver Biopsy, Genetic Testing (Phenotyping/Genotyping)

Notes:
Low levels suggest genetic deficiency; patients may require genetic confirmation. Smoking accelerates lung damage in deficiency cases.

Full Form: Alpha-1 Antitrypsin
Alternative Names: Alpha-1 Antitrypsin Test, Serum AAT Test, AAT Level Test, AAT Deficiency Test, Alpha-1 Protease Inhibitor Test, A1A Test, AATD Test, α1-Antitrypsin
Category: Biochemistry / Genetic & Liver Function Test

Purpose:

Alpha-1 antitrypsin (A1AT or A1A), a protein produced by the liver, protects the lungs against harm brought on by inflammation. Its absence can lead to emphysema and early liver damage. This test measures alpha-1 antitrypsin, a protein that protects tissues from enzymatic damage. It is diagnosed with alpha-1 antitrypsin deficiency, which can lead to lung and liver problems.

Commonly Ordered For:

• Early-onset emphysema or COPD
• Unexplained chronic liver disease
• Family history of Alpha-1 Antitrypsin Deficiency
• Evaluation of neonatal jaundice or hepatitis

Typical Normal Range:

Serum: 100 – 300 mg/dL (may vary by lab)

Related Tests: Liver Function Tests (LFTs), Pulmonary Function Tests (PFTs), Genetic Testing for AAT mutations, Chest X-ray / CT Scan, Liver Biopsy, Genetic Testing (Phenotyping/Genotyping)

Notes:
Low levels suggest genetic deficiency; patients may require genetic confirmation. Smoking accelerates lung damage in deficiency cases.

Full Form: Hemoglobin A1c
Alternative Names: HbA1c, Glycated Hemoglobin, Glycosylated Hemoglobin, Glycohemoglobin, A1c
Category: Biochemistry / Diabetes Test

Purpose:

Hemoglobin A1c (HbA1c) determines average blood glucose levels over the past 2 to 3 months by detecting the amount of hemoglobin bound to glucose in red blood cells. It is an essential tool for monitoring and diagnosing diabetes. It determines the proportion of glycated (glucose-bound) hemoglobin to assess long-term glycemic control over the past two to three months.

Commonly Ordered For:

• Screening and diagnosis of diabetes mellitus
• Monitoring long-term glycemic control in diabetic patients
• Assessing the risk of diabetic complications (kidney, eye, and heart disease)
• Differentiating between short-term and chronic hyperglycemia

Typical Normal Range:

Normal: < 5.7%
Prediabetes: 5.7 – 6.4%
Diabetes: ≥ 6.5%

Related Tests: Fasting Blood Glucose, Random Blood Glucose, Oral Glucose Tolerance Test (OGTT), Fructosamine, Continuous Glucose Monitoring (CGM), Autoantibody Tests, C-Peptide Test

Notes:
It is not affected by daily blood sugar fluctuations. However, it may be unreliable in patients with anemia, hemoglobin fluctuations, or recent bleeding.

Full Form: Alpha-1 Antitrypsin
Alternative Names: Alpha-1 Antitrypsin Test, Serum AAT Test, AAT Level Test, AAT Deficiency Test, Alpha-1 Protease Inhibitor Test, A1A Test, AATD Test, α1-Antitrypsin
Category: Biochemistry / Genetic & Liver Function Test

Purpose:

Alpha-1 antitrypsin (A1AT or A1A), a protein produced by the liver, protects the lungs against harm brought on by inflammation. Its absence can lead to emphysema and early liver damage. This test measures alpha-1 antitrypsin, a protein that protects tissues from enzymatic damage. It is diagnosed with alpha-1 antitrypsin deficiency, which can lead to lung and liver problems.

Commonly Ordered For:

• Early-onset emphysema or COPD
• Unexplained chronic liver disease
• Family history of Alpha-1 Antitrypsin Deficiency
• Evaluation of neonatal jaundice or hepatitis

Typical Normal Range:

Serum: 100 – 300 mg/dL (may vary by lab)

Related Tests: Liver Function Tests (LFTs), Pulmonary Function Tests (PFTs), Genetic Testing for AAT mutations, Chest X-ray / CT Scan, Liver Biopsy, Genetic Testing (Phenotyping/Genotyping)

Notes:
Low levels suggest genetic deficiency; patients may require genetic confirmation. Smoking accelerates lung damage in deficiency cases.

Full Form: Antibody
Alternative Names: Immunoglobulin Test, Ig, Serology Test, Specific Antibody Test, Antigen-Antibody Test, Immune Status Test, Titer Test
Category: Immunology / Serology

Purpose:

The immune system produces proteins called antibodies, or immunoglobulins, to recognize and eliminate pathogens such as bacteria, viruses, and poisons. Antibody screening tests can identify immune deficiencies, autoimmune diseases, and previous infections. Testing for antibodies in the blood can diagnose infections, autoimmune diseases, immune disorders, or vaccine responses.

Commonly Ordered For:

• Diagnosis of acute or past infections (viral, bacterial, parasitic)
• Evaluation of autoimmune diseases
• Determining immune response after vaccination
• Monitoring immunodeficiency disorders

Typical Normal Range:

• Depends on antibody type (IgG, IgA, IgM, IgE, IgD) and test method
• Generally: Negative (non-reactive) in absence of disease

Related Tests: Immunoglobulin Panel, Antigen Tests, Autoantibody Profiles (ANA, ANCA, RF), PCR (Polymerase Chain Reaction) Tests, CBC Test, Immunoglobulin (Ig) Levels, Autoantibody Tests

Notes:
Presence of antibodies indicates exposure or immune response; type and level help differentiate acute vs chronic conditions.

Full Form: Arterial Blood Gas
Alternative Names: Blood Gas Analysis, Arterial Blood Gasometry, Blood Gas Test, Arterial Blood Gas Analysis, Arterial Puncture, PaO2/PaCO2 Test
Category: Clinical Pathology / Critical Care

Purpose:

The main objectives of arterial blood gas testing are to assess acid-base balance, ventilation, and oxygenation by measuring oxygen (PaO₂), carbon dioxide (PaCO₂), and blood pH in an arterial blood sample. It is used to diagnose and treat lung, heart, and kidney conditions, such as respiratory failure, heart failure, diabetes, and sepsis, and is essential for evaluating the effectiveness of treatments.

Commonly Ordered For:

• Critically ill patients in ICU or ER
• Respiratory failure, COPD, asthma, pneumonia
• Monitoring patients on mechanical ventilation
• Suspected metabolic acidosis or alkalosis
• Assessment of oxygen therapy effectiveness

Typical Normal Range:

• pH: 7.35 – 7.45
• PaO₂: 75 – 100 mmHg
• PaCO₂: 35 – 45 mmHg
• HCO₃⁻: 22 – 26 mEq/L
• O₂ Saturation: 95 – 100%

Related Tests: Pulse Oximetry, Serum Electrolytes, Lactate, Spirometry, Venous Blood Gas (VBG), Basic Metabolic Panel (BMP), Comprehensive Metabolic Panel (CMP), Pulmonary Function Tests (PFTs)

Notes:
Requires arterial sample (commonly radial artery). Must be analyzed quickly; improper handling affects results.

Full Form: ABO Blood Group and Rh (Rhesus) Type
Alternative Names: Blood Grouping, Blood Typing, ABO/Rh Test
Category: Immunohematology / Blood Bank

Purpose:

The ABRH (ABO/Rh) blood typing test is designed to determine a person’s blood type and Rh factor, thereby ensuring the safety of blood transfusions and organ transplants and preventing pregnancy-related complications such as hemolytic disease of the fetus and newborn (HDN). It identifies the presence or absence of specific antigens on red blood cells, which is crucial for matching blood donors and recipients and therefore for avoiding severe immune reactions.

Commonly Ordered For:

• Blood transfusion compatibility testing
• Organ or tissue transplantation
• Prenatal and antenatal screening (to prevent Rh incompatibility)
• Emergency and routine blood typing

Typical Normal Range:

• ABO Group: A, B, AB, or O
• Rh Factor: Positive (+) or Negative (–)

Related Tests: Antibody Screen, Crossmatch, Antibody Screen (Indirect Coombs Test), Direct Antiglobulin Test (DAT) / Direct Coombs Test, Blood Transfusion

Notes:
Critical for transfusion safety; mismatched transfusions can cause life-threatening reactions. In pregnancy, Rh-negative mothers may require Rh immunoglobulin (RhIg) if carrying an Rh-positive baby.

Full Form: Antibody Titer
Alternative Names: Antibody Level Test, Serologic Titer, Antibody Serology Test, Immunization Test, Serological Antibody Testing, Antibody Serum Test, Red Cell Antibody Titration
Category: Immunology / Serology

Purpose:

The main purposes of an antibody titer test are to detect previous infections, assess the immune response in autoimmune diseases, and determine the effectiveness of vaccines and the need for booster doses. This test measures the amount of antibodies in a blood sample to assess the body’s exposure to specific antigens and the subsequent immune response against the disease or its own tissues.

Commonly Ordered For:

• Checking immunity after vaccination (e.g., Hepatitis B, Measles, Rubella)
• Detecting current or past infections
• Monitoring autoimmune conditions
• Assessing need for booster vaccines

Typical Normal Range:

• Reported as titer ratios (e.g., 1:20, 1:80, 1:160)
• Protective or abnormal levels vary by disease/test

Related Tests: Immunoglobulin Panel, Antigen Test, Neutralizing Antibody Test, Antinuclear Antibody (ANA) Test, C-Reactive Protein (CRP) Test, Antibody Screen and Identification

Notes:
A rising titer in paired samples (acute & convalescent) usually indicates recent infection. Protective thresholds differ by disease.

Full Form: Anti-Cardiolipin Antibodies
Alternative Names: aCL Antibodies, Cardiolipin Antibody Test, Antiphospholipid Antibody Test
Category: Immunology / Autoimmune Testing

Purpose:

The anti-cardiolipin antibody (ACA) test determines the presence of specific autoantibodies in the blood that increase the risk of blood clots, recurrent miscarriages, and certain autoimmune conditions like antiphospholipid syndrome (APS). The test helps doctors investigate unexplained clotting, recurring pregnancy loss, and symptoms suggestive of APS and other autoimmune diseases, such as lupus.

Commonly Ordered For:

• Recurrent blood clots (DVT, PE)
• Recurrent miscarriages or pregnancy complications
• Evaluation of systemic lupus erythematosus (SLE) and related autoimmune disorders
• Suspected antiphospholipid antibody syndrome

Typical Normal Range:

• Negative (non-reactive)
• May be reported as IgG, IgM, IgA levels in GPL/MPL units
• Low/negative = normal; Moderate/high = abnormal, linked to APS

Related Tests: Lupus Anticoagulant, Anti-β2 Glycoprotein I Antibodies, ANA Test, Complete Blood Count (CBC), Partial Thromboplastin Time (PTT) / Activated Partial Thromboplastin Time (aPTT)

Notes:
Persistent positivity (≥12 weeks apart) is required for APS diagnosis. May be transiently positive after infections or medications.

Full Form: Angiotensin Converting Enzyme
Alternative Names: Serum ACE, Serum Angiotensin Converting Enzyme (SACE)
Category: Biochemistry / Enzymology

Purpose:

An ACE blood test measures the level of angiotensin-converting enzyme in the blood and is primarily used to help diagnose and monitor sarcoidosis by detecting elevated enzyme levels caused by granulomas in the body. It can also help in monitoring the effectiveness of corticosteroid treatment for sarcoidosis, as levels should decrease with effective treatment. The test is also helpful in diagnosing Gaucher disease and can be elevated in other conditions, but sarcoidosis is its main application.

Commonly Ordered For:

• Suspected sarcoidosis
• Monitoring disease activity in sarcoidosis
• Evaluation of granulomatous diseases (e.g., tuberculosis, leprosy)
• Rarely for hypertension-related studies

Typical Normal Range:

• Adults: 8 – 52 U/L (may vary by lab)
• Children may have higher levels

Related Tests: Serum Calcium, Chest X-ray/CT, Pulmonary Function Tests, Lysozyme, Biopsy, CBC

Notes:
Elevated ACE supports but does not confirm sarcoidosis. Levels may also be raised in liver disease, diabetes, and infections. Some patients with sarcoidosis may have normal ACE.

Full Form: Anterior Cruciate Ligament
Alternative Names: Cruciate Ligament of Knee (Anterior), ACL Injury Test, Lachman Test, Anterior Drawer Test, Pivot Shift Test, Lever Sign Test
Category: Orthopedics / Sports Medicine

Purpose:

The primary purpose of Anterior Cruciate Ligament (ACL) (ACL) tests, such as the Lachman and Anterior Drawer tests, is to assess the integrity of the ACL and diagnose an injury by evaluating the forward movement of the tibia (shin bone) relative to the femur (thigh bone). A positive test result, indicating excessive anterior translation or a lack of a firm “end feel,” suggests a torn or unstable ACL, which often leads to knee instability and requires further evaluation.

Commonly Ordered For:

• Sports injuries (football, basketball, soccer, skiing)
• Knee instability or “giving way”
• Suspected ligament tear or rupture
• Pre- and post-surgical assessment

Typical Normal Range:

• Intact ligament with no laxity on physical exam
• Negative Lachman test / Anterior drawer test
• MRI shows intact ligament fibers

Related Tests: MRI Knee, X-ray (to rule out fractures), Arthroscopy, Lachman & Pivot-Shift Test, Instrumented Laxity Testing

Notes:
ACL injuries are common in athletes; may require surgical reconstruction for full function. Early rehab and strengthening reduce re-injury risk.

Full Form: Acid Phosphatase
Alternative Names: Serum Acid Phosphatase (SAP), Prostatic Acid Phosphatase (PAP), Tartrate-Resistant Acid Phosphatase (TRAP), Seminal Acid Phosphatase (SAP)
Category: Enzyme Test

Purpose:

The acid phosphatase test is used to diagnose diseases such as hairy cell leukemia, characterized by an elevation of a specific type of acid phosphatase. It can also be used as a marker to monitor the progression and response to treatment of prostate cancer and other diseases affecting the liver, bones, or blood.

Commonly Ordered For:

• Prostate cancer detection (historical use, less common now)
• Monitoring prostate carcinoma treatment
• Investigating metastatic prostate disease
• Certain bone or liver diseases

Typical Normal Range:

• 0–5.5 U/L (may vary by lab and method)

Related Tests: Prostate-Specific Antigen (PSA), Alkaline Phosphatase (ALP), Bone Scan, Digital Rectal Exam (DRE), Prostate Biopsy, TRAP Stain/Test (Tartrate-Resistant Acid Phosphatase), Bone Turnover Markers, Complete Blood Count (CBC)

Notes:
Largely replaced by PSA for prostate cancer screening; still occasionally used in specific clinical cases.

Full Form: Acid Phosphatase
Alternative Names: Serum Acid Phosphatase (SAP), Prostatic Acid Phosphatase (PAP), Tartrate-Resistant Acid Phosphatase (TRAP), Seminal Acid Phosphatase (SAP)
Category: Enzyme Test

Purpose:

The acid phosphatase test is used to diagnose diseases such as hairy cell leukemia, characterized by an elevation of a specific type of acid phosphatase. It can also be used as a marker to monitor the progression and response to treatment of prostate cancer and other diseases affecting the liver, bones, or blood.

Commonly Ordered For:

• Prostate cancer detection (historical use, less common now)
• Monitoring prostate carcinoma treatment
• Investigating metastatic prostate disease
• Certain bone or liver diseases

Typical Normal Range:

• 0–5.5 U/L (may vary by lab and method)

Related Tests: Prostate-Specific Antigen (PSA), Alkaline Phosphatase (ALP), Bone Scan, Digital Rectal Exam (DRE), Prostate Biopsy, TRAP Stain/Test (Tartrate-Resistant Acid Phosphatase), Bone Turnover Markers, Complete Blood Count (CBC)

Notes:
Largely replaced by PSA for prostate cancer screening; still occasionally used in specific clinical cases.

Full Form: Activated Clotting Time
Alternative Names: Activated Coagulation Time, Whole Blood Clotting Time (Activated), Whole-blood coagulation time
Category: Coagulation Test

Purpose:

The main objective of the coagulation activation test (TCA) is to monitor the effectiveness of anticoagulation with unfractionated heparin (HNF) in real time at the patient’s bedside. Esta prueba rápida, utilizado junto a la cama durante invasive procedures como la derivación cardiopulmonar, el cateterismo cardiací y las intervenciones coronaryias percutaneas, ayuda a garantiar que la sangre del paciente no coagule en exceso ni en defecto cuando se requiere terapia intensiva con heparina.

Commonly Ordered For:

• Prostate cancer detection (historical use, less common now)
• Monitoring prostate carcinoma treatment
• Investigating metastatic prostate disease
• Certain bone or liver diseases

Typical Normal Range:

• ~70–120 seconds (varies by method and device)

Related Tests: Activated Partial Thromboplastin Time(APTT), Prothrombin Time (PT/INR), Anti-Xa Assay, Thrombin Time,

Notes:
Less sensitive than aPTT; primarily used for point-of-care monitoring when rapid results are critical.

Full Form: Adrenocorticotropic Hormone
Alternative Names: Corticotropin, Adrenocorticotropic hormone blood test
Category: Endocrine/Hormone Test

Purpose:

The ACTH test is used to diagnose and monitor conditions that affect cortisol levels. These conditions include disorders of the pituitary and adrenal glands. High cortisol levels may be due to Cushing’s disease, a pituitary gland tumor that is usually benign (not cancerous).

Commonly Ordered For:

• Suspected Cushing’s syndrome
• Suspected Addison’s disease (primary adrenal insufficiency)
• Secondary adrenal insufficiency (pituitary cause)
• Monitoring ectopic ACTH production (e.g., tumors)

Typical Normal Range:

• ~10–60 pg/mL (morning sample; varies by lab and time of day)

Related Tests: Cortisol Test, Dexamethasone Suppression Test, Corticotropin-Releasing Hormone (CRH) Stimulation Test, Aldosterone, ACTH Stimulation Test, 24-Hour Urine Free Cortisol Test

Notes:
Levels show diurnal variation—highest in the morning, lowest at night; must be interpreted alongside cortisol.

Full Form: Adenosine Deaminase
Alternative Names: ADA Activity Test, ADA level, ADA enzyme activity, Adenosine deaminase assay
Category: Enzyme/Diagnostic Test

Purpose:

Adenosine deaminase (ADA) is an enzyme whose primary function is to remove toxic byproducts of DNA degradation, particularly deoxyadenosine. It converts deoxyadenosine and adenosine into harmless deoxyinosine and inosine, respectively. This crucial function protects lymphocytes and other cells from the accumulation of toxic metabolites, which is essential for the development and function of the immune system.

Commonly Ordered For:

• Suspected tuberculous pleural effusion
• Differentiation of TB from other causes of pleural effusion
• Supportive diagnosis in peritoneal or pericardial effusions
• Monitoring certain hematologic malignancies or immune disorders

Typical Normal Range:

• <40 U/L in pleural fluid (cut-off may vary by lab and specimen type)

Related Tests: Pleural Fluid Analysis, Acid-Fast Bacillus (AFB) Smear and Culture, Polymerase Chain Reaction (PCR) for Mycobacterium tuberculosis, Interferon-Gamma Release Assays, ADA Deficiency

Notes:
Elevated ADA is suggestive but not diagnostic of TB; must be interpreted with clinical and microbiological findings.

Full Form: Acid-Fast Bacillus
Alternative Names: Ziehl-Neelsen Stain, Auramine-Rhodamine Stain, Mycobacterial Smear, Acid-fast stain, TB culture and sensitivity, TB smear and culture, AFB smear and culture
Category: Microbiology/Diagnostic Test

Purpose:

What are acid-fast bacilli (AFB) tests? Acid-fast bacilli (AFB) are bacteria that cause tuberculosis and other mycobacterial infections, such as leprosy (Hansen’s disease). AFB tests are often ordered for people with symptoms of active tuberculosis, commonly known as TB.

Commonly Ordered For:

• Suspected pulmonary tuberculosis (sputum samples)
• Extrapulmonary TB (pleural fluid, CSF, urine, tissue biopsy)
• Monitoring response to anti-TB therapy
• Detection of nontuberculous mycobacterial infections

Typical Normal Range:

• Negative (no acid-fast bacilli seen)

Related Tests: Mycobacterial Culture, GeneXpert MTB/RIF, PCR for Mycobacterium tuberculosis, Chest X-ray, Nucleic Acid Amplification Test (NAAT), Tuberculin Skin Test (TST) or Interferon-Gamma Release Assay (IGRA)

Notes:
Smear sensitivity is lower than culture or PCR; at least 3 early morning sputum samples recommended for diagnosis.

Full Form: Alpha Fetoprotein
Alternative Names: α-Fetoprotein, Maternal Serum AFP (MSAFP), AFP Maternal, Quad screen (when part of a larger panel), AFP tumor marker
Category: Tumor Marker / Prenatal Screening Test

Purpose:

An alpha-fetoprotein (AFP) test measures AFP levels in the blood to detect potential problems during pregnancy, such as neural tube defects and chromosomal abnormalities, and to diagnose and monitor certain types of cancer and liver disorders in adults.

Commonly Ordered For:

• Screening for hepatocellular carcinoma (HCC)
• Monitoring treatment/recurrence in liver cancers and germ cell tumors
• Prenatal screening for neural tube defects (spina bifida, anencephaly)
• Prenatal screening for chromosomal abnormalities (e.g., Down syndrome, when combined in triple/quad screen)

Typical Normal Range:

• Adults: <10 ng/mL (non-pregnant)
• Pregnancy: Varies with gestational age (normally elevated)

Related Tests: β-hCG, Lactate Dehydrogenase (LDH), Ultrasound, Triple/Quad Screen, Liver Function Tests, Tumor markers, Imaging Tests, Biopsy,

Notes:
Elevated AFP can indicate liver disease, tumors, or fetal abnormalities; interpretation requires clinical context (especially in pregnancy).

Full Form: Antigen
Alternative Names: Immunogen, Surface Marker (context-specific, e.g., HBsAg, p24 Ag), Rapid Antigen Test (RAT), Antigen Rapid Test (ART), Rapid Antigen Detection Test (RADT), Lateral Flow Test (a common type of antigen test)
Category: Immunology / Infectious Disease Marker

Purpose:

Antigen tests analyze blood, sputum, urine, stool, or other body fluids to detect specific disease markers. They are often used to determine if you have a viral illness, such as the flu or COVID-19, or to monitor cancer treatment. They can also help evaluate organ donors and recipients.

Commonly Ordered For:

• Diagnosis of viral infections (e.g., HBsAg for hepatitis B, HIV p24 antigen)
• Bacterial antigen detection (e.g., Streptococcus pneumoniae, Legionella in urine)
• Tumor marker assays (certain cancer antigens)
• Monitoring response to treatment or vaccination

Typical Normal Range:

• Negative (antigen not detected)

Related Tests: Antibody Tests (Ab), PCR/NAAT, Culture, Serology Panels, Molecular Test (PCR)

Notes:
“Ag” is a general term; interpretation depends on the specific antigen test ordered. Usually paired with antibody testing for comprehensive evaluation.

Full Form: Acquired Immunodeficiency Syndrome
Alternative Names: HIV/AIDS (advanced stage of HIV infection), Antibody Tests, HIV Antibody Test, Enzyme Immunoassay (EIA), Enzyme-linked Immunosorbent Assay (ELISA)
Category: Infectious Disease / Immunodeficiency Disorder

Purpose:

Acquired immunodeficiency syndrome (AIDS) occurs in the most advanced stage of the infection. HIV attacks white blood cells, weakening the immune system. This makes it easier to contract diseases such as tuberculosis, infections, and certain types of cancer.

Commonly Ordered For:

• Confirming HIV infection (ELISA, Western Blot, HIV RNA PCR)
• Monitoring CD4+ T-cell count
• Monitoring HIV viral load
• Evaluating opportunistic infections or related malignancies

Typical Normal Range:

• Not applicable (syndrome, not a laboratory “normal” test); diagnostic definition includes CD4 <200 cells/µL or AIDS-defining illness.

Related Tests: HIV Antibody/Antigen Test, HIV RNA PCR, CD4 Count, Viral Load, Opportunistic Infection Panels, Western Blot,

Notes:
AIDS is the clinical end stage of HIV infection, not a single test; diagnosis requires confirmed HIV infection plus immunologic or clinical criteria.

Full Form: Aminolevulinic Acid
Alternative Names: δ-Aminolevulinic Acid, 5-ALA, Delta-ALA, Delta-Aminolevulinic Acid, Aminolevulinic Acid (ALA), Urine or Plasma, ALA, Delta, Random Urine, ALA, Delta, 24-Hour Urine
Category: Metabolic / Porphyrin Pathway Test

Purpose:

It acts as a crucial precursor to porphyrins (such as chlorophyll and heme) and as a growth regulator in plants, while in medicine it is used for the detection and treatment of tumors using photodynamic therapy (PDT) and to treat certain skin conditions.

Commonly Ordered For:

• Screening and diagnosis of acute intermittent porphyria (AIP)
• Differentiation of porphyrias from other causes of abdominal/neurologic symptoms
• Suspected lead poisoning (interferes with ALA dehydratase)
• Monitoring therapy in porphyria patients

Typical Normal Range:

• Urine: <4.5 mg/L (may vary by lab)

Related Tests: Porphobilinogen (PBG), Porphyrins (Urine, Feces, and Blood), Lead Level, Erythrocyte Protoporphyrin, Hereditary Tyrosinemia Type 1 Testing, Genetic Testing

Notes:
Elevated urinary ALA is a hallmark of acute porphyric attacks and lead toxicity; results should be interpreted with clinical context and other porphyrin studies.

Full Form: Albumin
Alternative Names: Serum Albumin, Urine Albumin, Microalbumin Test, Albumin-Creatinine Ratio (ACR)
Category: Protein / Liver & Kidney Function Test

Purpose:

The main functions of albumin are to maintain fluid balance in the blood vessels and to transport various substances, such as fatty acids, hormones, and medications, through the bloodstream. This is achieved by regulating plasma oncotic pressure, which prevents fluid leakage into the tissues. The liver produces albumin, and its levels are a key indicator of liver and kidney health.

Commonly Ordered For:

• Evaluation of liver disease (cirrhosis, hepatitis)
• Assessment of kidney disease (nephrotic syndrome, proteinuria)
• Monitoring nutritional status and malnutrition
• Investigation of edema or ascites

Typical Normal Range:

• Serum: 3.5 – 5.0 g/dL
• Urine: <30 mg/day (microalbuminuria: 30–300 mg/day)

Related Tests: Total Protein, Globulin, A/G Ratio, Liver Function Tests, Microalbumin/Creatinine Ratio, Comprehensive Metabolic Panel (CMP), Urine Protein Test

Notes:
Hypoalbuminemia may result from liver disease, nephrotic syndrome, malnutrition, or chronic illness; hyperalbuminemia is rare and usually due to dehydration.

Full Form: Alkaline Phosphatase
Alternative Names: ALP, Serum Alkaline Phosphatase, Alkp, Alk Phos
Category: Enzyme / Liver & Bone Function Test

Purpose:

The alkaline phosphatase test is often used to detect or diagnose liver or bone diseases. It can also help diagnose or monitor other health problems.

Commonly Ordered For:

• Suspected liver disease (hepatitis, cirrhosis)
• Suspected bile duct obstruction or cholestasis
• Bone disorders (rickets, osteomalacia, Paget’s disease)
• Monitoring cancer with bone or liver involvement

Typical Normal Range:

• ~44 – 147 U/L (varies by lab; higher in children and pregnancy)

Related Tests: Gamma-Glutamyl Transferase (GGT), Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Bilirubin, Calcium, Phosphate, ALP Isoenzyme Test,

Notes:
Elevated ALP may indicate liver or bone disease; isoenzyme testing (ALP fractionation) helps identify the source. Physiologically elevated in children (growth) and pregnancy.

Full Form: Alkaline Phosphatase
Alternative Names: ALP, Serum Alkaline Phosphatase, Alkp, Alk Phos
Category: Enzyme / Liver & Bone Function Test

Purpose:

The alkaline phosphatase test is often used to detect or diagnose liver or bone diseases. It can also help diagnose or monitor other health problems.

Commonly Ordered For:

• Suspected liver disease (hepatitis, cirrhosis)
• Suspected bile duct obstruction or cholestasis
• Bone disorders (rickets, osteomalacia, Paget’s disease)
• Monitoring cancer with bone or liver involvement

Typical Normal Range:

• ~44 – 147 U/L (varies by lab; higher in children and pregnancy)

Related Tests: Gamma-Glutamyl Transferase (GGT), Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Bilirubin, Calcium, Phosphate, ALP Isoenzyme Test,

Notes:
Elevated ALP may indicate liver or bone disease; isoenzyme testing (ALP fractionation) helps identify the source. Physiologically elevated in children (growth) and pregnancy.

Full Form: Alanine Aminotransferase
Alternative Names: Serum Glutamic Pyruvic Transaminase (SGPT), Alanine Transaminase (ALT), GPT
Category: Enzyme / Liver Function Test

Purpose:

The main function of the enzyme alanine aminotransferase (ALT) is to help the liver metabolize amino acids and convert food into energy. An ALT blood test measures the amount of this enzyme in the blood to assess liver health, as high ALT levels can indicate liver damage or inflammation.

Commonly Ordered For:

• Evaluation of liver disease (hepatitis, cirrhosis)
• Monitoring hepatotoxicity from drugs or toxins
• Assessment of non-alcoholic fatty liver disease (NAFLD)
• Workup of jaundice or abnormal liver function tests

Typical Normal Range:

• ~7 – 56 U/L (varies by lab)

Related Tests: Aspartate Aminotransferase (AST), ALP, Gamma-Glutamyl Transferase (GGT), Bilirubin, Albumin, PT/INR, Comprehensive Metabolic Panel (CMP), Liver Function Tests (LFTs),

Notes:
ALT is more liver-specific than AST; elevated levels usually indicate hepatocellular damage, though mild increases can occur in muscle injury.

Full Form: Antinuclear Antibody
Alternative Names: Antinuclear Factor (ANF), ANA panel, Fluorescent antinuclear antibody (FANA), ANA reflexive panel, Systemic lupus erythematosus – ANA (SLE-ANA)
Category: Autoimmune / Immunology Test

Purpose:

The ANA test is used to diagnose autoimmune diseases, such as systemic lupus erythematosus (SLE), the most common form of lupus. Lupus is a chronic (long-term) disease that affects many parts of the body, including the joints, skin, heart, lungs, blood vessels, kidneys, and brain.

Commonly Ordered For:

• Suspected systemic lupus erythematosus (SLE)
• Evaluation of other autoimmune disorders (scleroderma, Sjögren’s syndrome, mixed connective tissue disease)
• Workup of unexplained arthritis, rash, or systemic symptoms
• Monitoring disease activity in autoimmune conditions

Typical Normal Range:

• Negative (no detectable ANA; reported as titer and pattern if positive)

Related Tests: ENA Panel (Extractable Nuclear Antigens), Anti-dsDNA (anti-double-stranded DNA) Test, Anti-Smith Antibody, Rheumatoid Factor (RF), Anti-Cyclic Citrullinated Peptide (anti-CCP) Tests, C-Reactive Protein (CRP) , Erythrocyte Sedimentation Rate (ESR),

Notes:
A positive ANA is not diagnostic alone—seen in healthy individuals and multiple autoimmune diseases; interpretation requires clinical correlation and antibody pattern.

Full Form: Hepatitis B Core Antibody
Alternative Names: HBcAb, Total Anti-HBc, Anti-Hepatitis B core antigen
Category: Infectious Disease / Hepatitis B Serology

Purpose:

The HBsAg antibody test is a blood test used to detect the presence of antibodies, or markers, developed by the body in response to hepatitis B virus infection. It identifies and monitors treatment progress and diagnoses past, current, and future infections.

Commonly Ordered For:

• Diagnosis of acute or past hepatitis B infection
• Differentiating between acute, chronic, and resolved HBV status
• Screening in patients with unexplained liver disease
• Pre-transplant or pre-immunosuppressive therapy screening

Typical Normal Range:

• Negative (non-reactive)

Related Tests: Hepatitis B Surface Antigen (HBsAg), Hepatitis B Surface Antibody (Anti-HBs), Hepatitis B e-antigen (HBeAg), Anti-HBe, HBV DNA PCR, Liver Function Tests, Hepatitis B Core Antibody, IgM (IgM Anti-HBc),

Notes:
IgM anti-HBc → indicates recent/acute infection
Total anti-HBc (IgG + IgM) → indicates past or chronic infection
Not present after vaccination (only appears with natural infection)

Full Form: Hepatitis B “e” Antibody
Alternative Names: HBeAb, Hepatitis B e-Antibody, Anti-Hepatitis B e-antigen, HEAB
Category: Infectious Disease / Hepatitis B Serology

Purpose:

A reactive (positive) anti-HBe test when HBeAg levels have fallen below the detection threshold indicates the beginning of recovery in a person with hepatitis B. A nonreactive (negative) anti-HBe test may mean that the infection is very recent and that viral replication has not yet peaked.

Commonly Ordered For:

• Monitoring progression of chronic hepatitis B infection
• Evaluating infectivity and likelihood of viral replication
• Assessing response to antiviral therapy
• Differentiating between active replication and inactive carrier state

Typical Normal Range:

• Negative (non-reactive)

Related Tests: Hepatitis B Surface Antigen (HBsAg), Hepatitis B Surface Antibody (Anti-HBs), Hepatitis B Core Antibody (Anti-HBc), Hepatitis B “e” Antigen (HBeAg), Hepatitis B Viral DNA (HBV DNA), Liver Function Tests,

Notes:
Positive Anti-HBe with negative HBeAg → usually indicates lower infectivity and reduced viral replication
Seroconversion from HBeAg to Anti-HBe is a favorable response in chronic HBV treatment
Must be interpreted with HBV DNA levels for accurate infectivity statusIgM anti-HBc → indicates recent/acute infection
Total anti-HBc (IgG + IgM) → indicates past or chronic infection
Not present after vaccination (only appears with natural infection)

Full Form: Hepatitis B Surface Antibody
Alternative Names: HBsAb, Hepatitis B Surface Antibody, Quantitative, Antibody to Hepatitis B Surface Antigen
Category: Infectious Disease / Hepatitis B Serology

Purpose:

The anti-HBs test is designed to determine whether a person is immune to the hepatitis B virus (HBV) following vaccination or a previous infection. A positive or “reactive” result indicates immunity, meaning the person is protected and cannot transmit the virus. The presence of these antibodies is a key indicator of an effective immune response, confirming protection against future exposure to HBV.

Commonly Ordered For:

• Determining immunity after hepatitis B vaccination
• Identifying past, resolved hepatitis B infection
• Screening before immunosuppressive therapy or organ transplantation
• Assessing response to HBV vaccine in healthcare workers or high-risk individuals

Typical Normal Range:

• Negative (non-reactive); Protective immunity: ≥10 mIU/mL

Related Tests: Hepatitis B Surface Antigen (HBsAg), Hepatitis B Core Antibody (Anti-HBc), Hepatitis B e-antigen (HBeAg), Anti-HBe, HBV DNA PCR, Liver Function Tests, Hepatitis B Core Antibody, IgM (IgM Anti-HBc)

Notes:
Positive Anti-HBs with negative Anti-HBc → immunity from vaccination
Positive Anti-HBs with positive Anti-HBc → immunity from past infection
Lack of Anti-HBs after vaccination may indicate vaccine non-response

Full Form: Hepatitis C Virus Antibody
Alternative Names: HCV Antibody Test, Hepatitis C Antibody Test, Anti-Hepatitis C Virus, Antibody to HCV, Hepatitis C Ab
Category: Infectious Disease / Hepatitis C Serology

Purpose:

HCV antibody testing is an essential tool for the early detection, diagnosis, and treatment of hepatitis C virus infections. Whether used for routine screening or to diagnose an active infection, this test helps healthcare professionals understand the virus status and determine appropriate action.

Commonly Ordered For:

• Screening individuals at risk for HCV (blood transfusion history, IV drug use, hemodialysis)
• Evaluation of abnormal liver function tests
• Prenatal HCV screening in high-risk mothers
• Pre-surgical or pre-transplant infectious disease workup

Typical Normal Range:

• Negative (non-reactive)

Related Tests: Hepatitis C RNA Test (HCV RNA), HCV Genotype Test, Liver Function Tests, Liver Biopsy or Non-Invasive Fibrosis Tests, Qualitative HCV RNA Test, Quantitative HCV RNA Test (Viral Load)

Notes:
Positive Anti-HCV indicates exposure but does not distinguish between past, resolved, or active infection.
Confirmatory testing with HCV RNA PCR is required to determine active infection.
Antibodies usually appear 8–12 weeks after exposure.

Full Form: Alkali Denaturation Test (APT Test for Fetal Hemoglobin)
Alternative Names: APT Test, Apt-Downey Test, Alkali Denaturation Test, Fetal Hemoglobin Test
Category: Hematology / Gastrointestinal Test (Neonatal)

Purpose:

The APT test is used to differentiate neonatal blood from maternal blood in meconium. This test requires a sufficient amount of blood to be detectable with the naked eye.

Commonly Ordered For:

• Evaluation of blood in stool or vomitus of newborns
• Distinguishing maternal blood swallowed during delivery from true neonatal GI bleeding
• Assessment of suspected neonatal upper GI hemorrhage
• Clarification of unclear neonatal rectal bleeding

Typical Normal Range:

• Negative (no fetal hemoglobin detected in stool/vomitus)

Related Tests: Occult Blood Test, Hemoglobin Electrophoresis, Complete Blood Count (CBC), Kleihauer-Betke (KB) Test, Coagulation Studies

Notes:
Based on resistance of fetal hemoglobin (HbF) to alkali denaturation, unlike adult hemoglobin.
Useful only in neonatal period; not recommended for older infants or adults.

Full Form: Activated Partial Thromboplastin Time
Alternative Names: Partial Thromboplastin Time (PTT), Partial Thromboplastin Time (Activated), Intrinsic Pathway Coagulation Factor Profile, APTT
Category: Coagulation Test

Purpose:

The purpose of an aPTT test is to evaluate the intrinsic and common pathways of the coagulation cascade, measure the time it takes for a blood clot to form, and monitor heparin treatment.

Commonly Ordered For:

• Monitoring unfractionated heparin therapy
• Screening for bleeding/clotting disorders (hemophilia, von Willebrand disease, lupus anticoagulant)
• Preoperative coagulation assessment
• Investigation of unexplained bleeding or thrombosis

Typical Normal Range:

• ~25 – 35 seconds (varies by lab and reagent)

Related Tests: PT/INR, ACT, Fibrinogen, Anti-Xa Assay, Mixing Studies, Thrombin Time (TT), Coagulation Factor Assays, Bleeding Time, Platelet Count

Notes:
Prolonged aPTT suggests intrinsic pathway abnormalities or heparin effect.
Normal aPTT with prolonged PT indicates extrinsic pathway defect.
Must be interpreted with clinical history and other coagulation studies.

Full Form: Antistreptolysin-O Antibody
Alternative Names: ASO Titer, Anti-Streptolysin O, Streptolysin-O Antibody, Streptococcal Serology
Category: Serology / Infectious Disease Test

Purpose:

The ASO (antistreptolysin O) test measures ASO antibodies in blood to detect a recent group A streptococcal infection, such as Streptococcus pyogenes. It is not used to diagnose active streptococcal infections, but it helps diagnose post-streptococcal complications, such as rheumatic fever or post-streptococcal glomerulonephritis, which can occur after untreated infections.

Commonly Ordered For:

• Suspected post-streptococcal complications (rheumatic fever, post-streptococcal glomerulonephritis)
• Evaluation of recent streptococcal pharyngitis or skin infection
• Differentiating acute rheumatic fever from other causes of arthritis or carditis
• Monitoring antibody decline after treatment

Typical Normal Range:

• Adults: <200 IU/mL
• Children: <400 IU/mL (values vary by lab)

Related Tests: Anti-DNase B, Throat Culture, Rapid Strep Test, Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP), Urinalysis

Notes:
Elevated ASO indicates recent streptococcal exposure but not the site of infection.
Titers peak 3–5 weeks after infection and decline over months.
Often used in combination with Anti-DNase B for higher sensitivity.

Full Form: Aspartate Aminotransferase
Alternative Names: SGOT (Serum Glutamic-Oxaloacetic Transaminase), Aspartate Transaminase
Category: Liver Function / Enzyme Test

Purpose:

An AST blood test is often part of a routine blood test to assess liver health. This test can help diagnose or monitor liver problems. It can also help diagnose other health problems.

Commonly Ordered For:

• Suspected liver disease (hepatitis, cirrhosis)
• Monitoring alcohol-related liver injury
• Evaluation of myocardial infarction (historically, less common now)
• Muscle disorders or injury

Typical Normal Range:

• 10 – 40 U/L (may vary by lab)

Related Tests: ALT (Alanine Aminotransferase) Test, Alkaline Phosphatase (ALP), GGT (Gamma-Glutamyl Transferase), Bilirubin, CK, Liver Function Panel (or Liver Panel), Comprehensive Metabolic Panel (CMP), Albumin and Total Protein

Notes:
Elevated AST alone is not specific; AST/ALT ratio aids in differential diagnosis (e.g., alcoholic liver disease).

Full Form: Antithrombin-III Activity
Alternative Names: AT, Antithrombin Activity, AT3, Antithrombin activity, Antithrombin, functional, Heparin cofactor activity, Serine protease inhibitor
Category: Coagulation / Thrombophilia Workup

Purpose:

This test measures antithrombin III activity in the blood. Abnormal levels may indicate a risk of excessive blood clotting or bleeding.

Commonly Ordered For:

• Unexplained or recurrent venous thrombosis
• Suspected inherited thrombophilia
• Monitoring patients on heparin therapy (resistance to heparin)
• Evaluation of disseminated intravascular coagulation (DIC)

Typical Normal Range:

• 80 – 120% activity (may vary by lab)

Related Tests: Protein C, Protein S, Factor V Leiden, PT, aPTT, Antithrombin Antigen Test, Lupus anticoagulant test.

Notes:
Low AT III may be inherited or acquired (liver disease, nephrotic syndrome, heparin therapy, DIC).