Hemoglobin (Hb%) Test Purpose, Procedure, Principle, Result Interpretation and Normal Values
Definition: Measurement of hemoglobin concentration in blood to assess oxygen-carrying capacity.
Purpose: Evaluate anemia, polycythemia, blood loss, and overall oxygen transport status.
| Other Names | Hb, Hgb, Hemoglobin count, Haemoglobin, Hb level |
| Test Technique | Drabkin Method, Sahli’s Acid Hematin Method, Automation |
| Test Type | Blood Test |
| Turnaround time (TAT) | 4 – 6 Hours (Veries by Lab, Method, Transport etc.) |
| Test Cost ($) | 1$ – 30$ (Depends on Your Country and Lab) |
| Fasting Required | Not required |
| Medications | Some drugs may influence hemoglobin results:May Increase Hb: Diuretics, Erythropoietin, Anabolic steroidsMay Decrease Hb: Chemotherapy drugs, Chloramphenicol, Zidovudine |
| Allowed/Avoid | Everything Allowed. Avoid alcohol 24 hours prior. |
| Other Preparation | No Any Other Special Preparation |
- Required Sample: 3-5 mL Blood
- Specimen (s) Container: Lavender-top EDTA tube
- Alternative Specimen(s): Heparin tube, Sodium citrate tube, Double oxalate tube
- Sample Stability:
• Room Temp (20-25°C): Upto 24 Hours
• Refrigerated (2-8°C): Upto 7 days
• Frozen (-20°C and Below): Not recommended (causes hemolysis) - Transport: Transport in EDTA tube in Cooling Box
- Mislabeling Or Unlabeled sample: Patient identification error
- Wrong collection tube: Incorrect additive interferes with tests
- Insufficient volume (QNS): Not enough blood for testing
- Clotted sample: Anticoagulated tube clotted, unusable
- Hemolyzed sample: RBC rupture affects test results
- Delayed transport: Sample deterioration before testing
- Hemoglobin (Hb)
| Adult Male | 13 – 18 g/dL |
| Adult Female | 12 – 16 g/dL |
| Childrens (Upto 7 Years) | 11 – 14 g/dL |
| Newborn | 14 – 23 g/dL |
Test Introduction / Definition:
The hemoglobin (Hb%) test measures the concentration of hemoglobin in blood. Hemoglobin is an iron-containing protein found in red blood cells responsible for transporting oxygen from the lungs to body tissues.
The hemoglobin test is a laboratory investigation that determines the amount of hemoglobin present in blood, reflecting the oxygen-carrying capacity of red blood cells and helping diagnose anemia, polycythemia, and other hematological disorders.
Principle of the Test:
Most laboratories use the Cyanmethemoglobin (Drabkin) method.
Biochemical/Analytical Principle
- Blood is mixed with Drabkin’s reagent.
- Potassium ferricyanide oxidizes hemoglobin to methemoglobin.
- Methemoglobin reacts with potassium cyanide forming cyanmethemoglobin (HiCN).
- The colored compound absorbs light at 540 nm.
- Absorbance is proportional to hemoglobin concentration.
Detection Method
- Spectrophotometry / Colorimetry
Test Purpose / Clinical Indications:
Doctors order hemoglobin testing to:
- Monitor treatment response for anemia
- Diagnose anemia
- Detect polycythemia
- Monitor blood loss
- Evaluate nutritional deficiencies
- Monitor chronic diseases
- Assess bone marrow function
Specimin Requiremenst:
Patient Preparation:
- Inform doctor about medications
- No fasting required
- Avoid strenuous activity before test
Sample Required:
2–3 mL EDTA whole blood
Haemoglobin (Hb%) Test Procedure (Manual / Semi-Automated)
- Spectrophotometer / Colorimeter
- Calibrated Micropipettes
- Disposable Tips & Cuvettes
- Test Tubes
- EDTA Blood Sample
- Drabkin’s reagent (Ready- to Use)
- Hemoglobin standard
- Control samples
Drabkin’s reagent contains:
- Potassium ferricyanide: 200 mg
- Potassium cyanide: 50 mg.
- Potassium phosphate buffer: 140 mg
- Non-ionic detergent: 1 ml.
- Distilled water: 1 Liter.
Drabkin’s Reagent: Store at 15-25°C:
| Wavelength | 546nm, 500 nm |
| Cuvette | 1 cm light path |
| Temperature | RT – 15-25°C |
| Measurement | Against working reagent blank |
| Pipetting Step | Blank | Standard | Test (Sample) |
|---|---|---|---|
| Drabkin’s (Ready) reagent | 5000 µL (5ml) | 5000 µL (5ml) | 5000 µL (5ml) |
| Standard | — | 20 µL | — |
| Sample | — | — | 20 µL |
| INCUBATION:Mix gently and Incubate 3-5 mints @ 20 – 25°C (Room Temperature). | |||
Linear up to 20 g/dL. Turbid samples may cause interference.
- Use low and high hemoglobin controls.
- Calibrate spectrophotometer regularly.
- Run daily QC samples.
- Maintain reagent expiry checks.
- Participate in external quality assurance programs.
- Lipemia, Dehydration, Hemolysis, High altitude.
- Smoking, Pregnancy, Blood transfusion, Drugs affecting erythropoiesis.
Hb results correlate with:
- Hematocrit (HCT).
- RBC Count.
- Reticulocyte count.
- Iron studies.
- Ferritin.
Hb levels correlate clinically with:
- Oxygen transport capacity.
- Bone marrow function.
- Nutritional status.
- Chronic diseases.
- Blood loss.
- Hemolysis.
Hemoglobin (Hb%) Test Normal Values with Both Units (Conventional and SI)
*mmol/L is calculated based on the Hemoglobin Tetramer molecular weight.
Test Result Interpretation:
| Result | Possible Conditions |
|---|---|
| Normal Hb% | Healthy oxygen transport |
| Low Hb% | Iron deficiency anemia, bleeding, chronic disease |
| High Hb% | Polycythemia, dehydration, chronic hypoxia |
Test Clinical Significance:
Normal Test Result:
- Adequate oxygen transport
- Normal RBC production
Low Test Result Causes:
- Iron deficiency anemia
- Vitamin B12 deficiency
- Chronic kidney disease
- Bone marrow disorders
- Acute or chronic bleeding
- Hemolytic anemia
High Test Result Causes:
- Polycythemia vera
- Chronic lung disease
- Severe dehydration
- Living at high altitude
- Smoking
- Congenital heart disease
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Frequently Asked Questions (FAQs):
What does the hemoglobin test measure?
It measures the amount of hemoglobin protein in red blood cells.
Is fasting required for the Hb test?
No fasting is required.
What causes low hemoglobin?
Common causes include anemia, blood loss, nutritional deficiencies, and chronic diseases.
What causes high hemoglobin?
High levels may occur due to dehydration, smoking, or polycythemia.
Is hemoglobin part of a CBC test?
Yes, hemoglobin is a key parameter of the Complete Blood Count.
What is the most accurate method for Hb estimation?
The cyanmethemoglobin (Drabkin) method is considered the reference method.
Can dehydration affect Hb results?
Yes, dehydration may falsely increase hemoglobin concentration.
What is the normal hemoglobin level in adults?
Typically 13–18 g/dL in men and 12–16 g/dL in women.
How long does the Hb test take?
Usually less than 1–2 hours in routine laboratories.
Why is Hb important?
It reflects oxygen transport capacity of blood.
Related Tests & Diseases:
Related Tests:
Related Diseases/Conditions
References:
- WHO Anemia Detection Guide – WHO – (Accessed on Mar 09, 2026)
- Clinical Hematology Principles and Procedures – Archive – (Accessed on Mar 09, 2026)
- Tulip Diagnostics Hemoglobin Reagent Insert – Tulip Diagnostic – (Accessed on Mar 09, 2026)
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