Alkaline Phospatase (ALP) Review Questions and Answers

1.    Discuss the principle of the test.

ALP catalyzes the hydrolysis of Paranitrophenylphosphate, which is colorless, to paranitrophenol, which is colored yellow, at 405 nanometers.

2.     Name differences between ALP and ACP

CATEGORY                  ALP                                                    ACP
pH                            Basic or alkaline                                      acidic
Best specimen     Heparinized plasma (Calbreath)                  Serum citrated plasma (Calbreath)
Tissue source    Same as ACP except for prostate,                  more on bone
Clin. significance    Prostate, platelets, bone, liver, spleen, kidneys, erythrocytes
Diagnostic significance    Hepatobiliary and bone disorders    Prostatic carcinoma

3.    What is the reason for diluting serum if the absorbance is higher than 0.25

For more precise and accurate measurement of the concentration of the unknown.

4.    Why do we have to adjust the spectrophotometer to zero when we read unknown solutions?

To read out errors caused by the spectrophotometer and the reagent.

5.    What is the best sample for this determination?

Unhemolyzed, clear, non-icteric, non-lipemic serum

Questions and Answers on Clinical Enzymology (ACP)

1. Discuss the principle of the most common principle of the ACP test.

ACP catalyzes the hydrolysis of Paranitrophenylphosphate, which is colorless, at an acidic pH, to paranitrophenol, which is colored yellow, at 450 to 470 nanometers.

2. Why do you have to utilize a specific wavelength in measuring ACP?

To be able to get the maximum reading of ACP in the sample.

3. What is the ideal specimen for the ACP determination?

Citrated blood is ideal, but for the determination performed in the lab, it is serum.

4. Name sources of errors for ACP test

Hemolyzed serum falsely increases values

Turbid and icteric serum need serum blanking for accuracy

Some reagents are photosensitive, exposure to light would decrease values

Prolonged or shortened incubation time would increase and decrease values respectively

Alkaline pH would decrease values

Altered temperatures could either increase or decrease values