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Sample

  1. It is done on the serum of the patient and performs the test within one hour.
    • How to get good serum: Take 3 to 5 ml of blood in the disposable syringe or in vacutainer. Keep the syringe for 15 to 30 minutes and then centrifuged for 2 to 4 minutes to get clear serum.
  2. EDTA plasma is better because it stabilizes the acid phosphatase.
  3. Morning sample is preferred.
  4. Avoid hemolysis.
  5. The sample is stable for 24 hours at 2 to 8 °C.
  6. Try to do the test immediately.
  7. If serum is acidified below pH of 6.5 that will stabilize the enzyme.

Precaution

  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% activity lost if kept at the room temperature.

Purpose of the test (Indications):

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

Pathophysiology:

  1. Acid phosphatase enzymes are found in lysosomes of various tissue like Prostate, bone, kidney, RBC, platelets, semen, liver and spleen. 
    1. High levels are also found in white blood cells like monocytes and lymphocytes.

  1. Acid phosphatase (AP) which is derived from the prostate has a pH optimum the range of 5 to 6.
    1. All phosphatases have optimal activity below pH of 7.0
    2. Difference between AP and alkaline phosphatase:
    3.   Acid phosphatase Alkaline phosphatase
      pH 5.0 >7.0
  2. The greatest concentration of AP activity occurs in the liver, spleen, milk, platelets, bone marrow, red blood cells, and the prostate gland.

  1. The prostate is the richest source. Majority of AP arises from the RBCs and prostatic tissue. 
  2. AP enzymes are unstable especially at a temperature above 37 °C and at a pH level of above 7.0.
    1. If prostate AP is left at room temperature then its 50% activity will be lost in one hour.
  3. As the prostatic component (PAP) is not raised in the early prostatic diseases so this is not a good screening enzyme.
  4. Total acid phosphatase consists of a one-half prostatic component and the rest of liver, disintegrating platelets, and RBCs.
  5. Acid phosphatase is a lysosomal enzyme, so the prostatic enzyme is found in the lysosome of prostatic epithelium and is a glycoprotein.

  1. Acid phosphatase activity is 100 times more in the prostate than other tissues, so prostate is the richest source.
  2. Once prostatic cancer spreads, the level of AP starts rising and significantly raised when there is metastasis particularly in the bone.
    1. The raised level in 80% of the patient with metastasis is age-related.
    2. It is raised in Prostatic carcinoma, particularly its prostatic component.
  3. Total AP is raised in Bone diseases.
  4. Prostatic acid phosphatase needs to be differentiated from the non-prostatic sources like RBCs source.
    1. Total AP = AP after tartarate inhibition = Prostatic AP.

Normal

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.

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 day.

  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's value is 10 U/L and in the coital lady is >50 U/L.

Test value for the layman:

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

 


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