Prostatic Acid Phosphatase (PAP), Acid Phosphatase

Table of Contents

Prostatic Acid Phosphatase (PAP)

It is done on the patient’s serum.
1. Separate the serum immediately to decrease the contact with RBCs.
2. The sample can be stabilized by adding 10 mg/mL of disodium citrate monohydrate to the serum.
3. Or add the 50 µL of acetic acid (5 mol/L) per mL of the serum to lower the pH to 5.4.
Separate serum immediately and perform the test.

If there is a delay, add citrate buffer or acetic acid to reach a pH of 5.4 to 6.2. Otherwise, enzyme activity will rapidly lose its ability to function.
If the sample is kept at room temperature for more than one hour, 50% of the activity is lost.
Avoid hemolysis. The hemolysed sample is contaminated with isoenzyme and should be discarded.
The lipemic serum also interferes with the reading of the final result because of turbidity.
It can be stored at 4 C° or -20 °C.
The sample is unstable at a temperature of >37 °C.
The sample is also unstable at a pH of >7.0.

For the diagnosis of prostatic carcinoma.
This is raised in prostatic carcinoma and metastasis due to prostatic carcinoma.

Prostatic Acid Phosphatase (PAP): Acid phosphatase enzyme

Prostatic acid phosphatase is a subtype of total Acid phosphatase.
The prostatic component is found in the lysosomes of the prostatic epithelium.
1. This glycoprotein has a molecular weight of 100,000 and a biological half-life of 1.1 to 2.6 hours.
Very small amounts of Acid phosphatase are found in the liver, RBCs, Spleen, Platelets, and bone marrow, with a negligible quantity of Prostatic acid phosphatase.
The greatest activity is present in the prostate, the richest source. It gives a small amount in the blood of a healthy person.

Acid phosphatase distribution in the body

AP is raised in 50% to 75% of the cases with local invasion of prostatic carcinoma.
1. AP is raised in >90 % of cases of metastatic disease.
2. Acid phosphatase has an optimal activity below a pH of 7.0.
3. AP is unstable, especially at room temperature at 37 °C and a pH of >7.0.
4. AP activity is lost >50% in one hour at room temperature.
5. Acidification of the serum to a pH of <6.5 will stabilize the enzyme.
Erythrocyte AP is inhibited by formaldehyde and cupric ions, which make Prostatic AP resistant.
Tartrate-resistant phosphatase is very helpful in the diagnosis of hairy cell leukemia.
Prostatic acid phosphatase (PAP) is replaced by:
1. The PSA (Prostatic specific antigen).
2. Digital rectal examination.
3. Transrectal ultrasonography.
4. Surgical biopsy of the prostate for histopathology.
5. Total body bone scan.

Source 1

Source 2

Source 3

Prostatic acid phosphatase = <2.5 ng/mL (immunoassay)
- Tartarate inhibition method = 0 to 0.6 U/L

Source 4

Prostatic carcinoma.
Prostatic massage.
TUR.
Leukemia (Myeloid leukemia and hairy cell leukemia).
Bone disorder, e.g., Paget’s disease, metastatic carcinoma from breast and lung.
This is raised in osteoclastoma (Giant cell tumor), Osteoclastic tumors, and osteopetrosis.
Storage disorder, e.g., Gaucher’s disease, Niemann picks disease.
Hyperparathyroidism with bone involvement.

The importance of Acid phosphatase (AP) in the semen is very important to rule out the case of rape because AP has a high concentration in the semen.
The swab from the victim is kept in 2.5 ml of broth.
- Or store in normal saline. Freeze and thaw the sample at 2 to 4 °C before performing the test.
- Store at room temperature or 4 °C.
- Specimen retains Acid phosphatase (AP) activity for one month.

NOTE: Please see more details in the Acid phosphatase total.

Question 1: What is the significance of prostatic acid phosphatase?

Question 2: What is the medicolegal value of acid phosphatase?