AP Test Purpose, Procedure, Result Interpretation and Your Test Result Meaning

The AP (Acid Phosphatase) test, also known as the Acid Phosphatase assay or Acid Phosphatase measurement, is a medical laboratory test used to measure the levels of acid phosphatase enzyme in a patient’s blood serum or other body fluids. This test is primarily performed to aid in the diagnosis and monitoring of certain medical conditions, especially those related to the prostate gland.

Also Known as	Acid Phosphatase, Prostatic Isoenzyme, PAP, Prostatic Acid Phosphatase, AP
Test Purpose	To diagnose the prostatic carcinoma
Test Preparations	No Need any Preparation
Test Components	Total Acid Phosphatase
Specimen	2 ml Clotted or Heparinized Blood
Stability Room	6 Hours
Stability Refrigerated	7 Days
Stability Frozen	180 Days
Method	ELISA
Download Report	Download Report

Prostatic acid phosphatase has been used as a tumor marker since Gutman observed in 19381 that elevated levels of this enzyme were found in patients with metastatic prostate cancer. Measurement of PAP in conjunction with PSA measurements is useful in evaluating the prognosis of prostate cancer. Measurement of two markers can identify prostate cancer patients who have elevated PAP but not PSA and, therefore, Therefore, they help monitor the course of the disease and the response to it. treatment. PAP is more specific than PSA and fewer false positives are seen due to benign prostatic hyperplasia.

Purpose Of The Test:

1. To diagnose the prostatic carcinoma by advising the estimation of Total acid phosphatase and the prostatic component.
2. These two enzymes stage the prostatic carcinoma and monitor the effectiveness of treatment.
3. The test for acid phosphatase can be done on a vaginal swab in rape cases. Because the seminal fluid is rich in acid phosphatase.

Sample:

SPECIMEN TYPE 

Serum

SPECIMEN REQUIRED 

Patient Preparation: For 12 hours before specimen collection, do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.

Collection Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

SPECIMEN MINIMUM VOLUME 

0.4 mL

REJECT DUE TO 

Gross hemolysis	Reject
Gross lipemia	OK

SPECIMEN STABILITY INFORMATION 

Specimen Type	Temperature	Time	Special Container
Serum	Refrigerated (preferred)	7 days
	Frozen	180 days

Precaution for Specimins

1. It has poor stability in whole blood.
2. ACP is unstable at room temperature >37 °C.
3. ACP is unstable if the pH is >7.0.
4. The serum is separated immediately and the test is performed within one hour.
5. EDTA plasma is preferred that stabilizes the AP.
6. Avoid prostatic massage in the last 48 hours.
7. Hemolysis falsely raised the value.
8. 50% of activity lost if kept at room temperature.

Acid Phosphatase:

• Acid phosphatase enzymes are found in lysosomes of various tissue like Prostate, bone, kidney, RBC, platelets, semen, liver and spleen.
• Acid phosphatase (AP) which is derived from the prostate has a pH optimum of the range of 5 to 6.
• The greatest concentration of AP activity occurs in the liver, spleen, milk, platelets, bone marrow, red blood cells, and the prostate gland.
• The prostate is the richest source. The majority of AP arises from the RBCs and prostatic tissue.
• AP enzymes are unstable especially at a temperature above 37 °C and at a pH level of above 7.0.
• As the prostatic component (PAP) is not raised in the early prostatic diseases so this is not a good screening enzyme.
• Total acid phosphatase consists of a one-half prostatic component and the rest of the liver, disintegrating platelets, and RBCs.
• Acid phosphatase is a lysosomal enzyme, so the prostatic enzyme is found in the lysosome of prostatic epithelium and is a glycoprotein.
• Total AP is raised in Bone diseases.
• Prostatic acid phosphatase needs to be differentiated from the non-prostatic sources like RBCs source.
  • Total AP = AP after tartarate inhibition = Prostatic AP.

Normal Values:

• Total acid phosphatase
  • 2.5 to 3.7 ng /mL or 2.5 to 3.7 µg/L.
  • or less than 3.0 mg /L.
• Prostatic acid phosphatase  =  <2.5 ng/mL (0 to 0.6 U/L).
• Other reference
  • Adult 0.13 to 0.63 units/L at 37 °C
  • or 2.2 to 10.5 units/L (SI units).
  • Child 8.6 to 12.0 units/mL at 30 °C.
  • Newborn  10.4 to 16.4 units /mL at 30 °C.

Moderately Raised Levels Seen In, Other Than Prostatic Carcinoma:

1. Niemann-Pick disease.
2. Gaucher’s disease.
3. Prostatitis and Benign prostatic hyperplasia ( BPH ).
4. Urinary retention.
5. Any cancer that has given metastasis to the bones.
6. Myeloid Leukemia.
7. Multiple myelomas.
8. Paget disease.
9. Sickle cell anemia.
10. Renal diseases.
11. Liver diseases like cirrhosis.
12. Thrombocytosis.
13. Hyperparathyroidism.

The Raised Level Is Seen In:

1. Significantly raised level seen in prostatic carcinoma.
2. Benign prostatic hyperplasia.
3. Prostatitis.
4. Metastatic carcinoma of the prostate.
5. Metastases to the bones.

Important Facts:

1. After the surgery, its level will drop in 3 to 4 days.
2. With estrogen therapy takes 3 to 4 weeks to drop the level.
3. Acid phosphatase is not recommended for screening of prostatic carcinoma because it’s level is not usually significantly raised until the tumor has the metastasis.
4. Acid phosphatase is not advised in routine to diagnose prostatic carcinoma, in case the following parameters are recommended:
   1. Per-rectal digital examination.
   2. Transurethral ultrasound image.
   3. Histologic examination of the prostatic biopsy.
   4. Total body scan.
   5. The Prostatic specific antigen is advised.

Medicolegal Importance:

1. There is a high concentration in the semen, so its measurement is important in the rape cases.
2. Take the vaginal swab and keep it in 2.5% of broth and can store at  4 °C or room temperature.
   1. Result: In noncoital ladies it values is 10 U/L and in the coital lady is >50 U/L.

• However, PSA is more specific and sensitive than acid phosphatase.

Test Value For The Layman:

1. This test is advised for the diagnosis of prostatic cancer.
2. It can be advised in case of rape on the vaginal swab.

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Possible References Used

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