What is Alkaline Phosphatase (ALP)?
A common clinical chemistry laboratory test that measures the level of the enzyme Alkaline Phosphatase (ALP) in the blood. ALP is present in almost all forms of life and is thought to have a role in the provision of phosphate to tissue or the activation/inactivation of substrates via dephosphorylation. In humans, ALP can be found in various tissues throughout the body, including the liver, bones, intestines, kidneys, and placenta during pregnancy.
Why test ALP?
Abnormal levels of ALP reflect damage to tissue or disruption of normal bodily processes. Therefore, ALP is often included as part of the other blood tests and is typically included as part of a comprehensive metabolic panel or Liver Function Tests (LFT).
Elevated levels of ALP in the blood may indicate liver damage or disease, such as hepatitis, cirrhosis, or liver cancer. Additionally, certain bone conditions, such as Paget’s disease, osteomalacia, or bone metastasis, can also cause increased ALP levels. Conversely, decreased levels of ALP are less common but can be seen in certain genetic disorders, malnutrition, or severe vitamin C deficiency.
It’s important to note that ALP levels alone are not diagnostic of a specific condition but rather serve as an indicator of potential liver or bone problems. Further testing and clinical evaluation are usually necessary to determine the underlying cause of any abnormalities in ALP levels.
ALP testing is based on the hydrolysis of p-nitrophenyl phosphate (pNPP) substrate. To hydrolyze p-nitrophenyl phosphate (pNPP) substrate and measure alkaline phosphatase (ALP) activity, various buffers can be used. The choice of the buffer depends on the specific assay kit or laboratory protocol being followed.
Commercially available ALP methods typically vary in the buffer used. The preferred buffering system, according to the IFCC, is AMP (2-amino-2-methyl-1-propanol) 1. AMP is the most optimized method for ALP and helps to maintain the appropriate pH range for ALP activity. Other possible buffers would be Tris Carbonate (tris(hydroxymethyl)aminomethane) or DEA buffer.
Why ELITechGroup Alkaline Phosphatase (ALP)?
The ELITechGroup ALP method is based on the most recent recommendations of the International Federation of Clinical Chemistry (IFCC)1 to ensure traceable accuracy and performance. The method utilizes 4-nitrophenylphosphate as the substrate and also contains a metal ion buffer system to ensure that optimal concentrations of Zinc and Magnesium are maintained. The metal ion buffer can also chelate other potentially inhibitory ions which may be present. The reaction is monitored by measuring the rate of increase in absorbance at 405 nm which is proportional to the activity of ALP in the serum.
The ELITechGroup ALP is traceable to the IFCC reference method, simplifying peer-to-peer comparison with EQAP. The liquid-stable ready-to-use reagents are barcoded to streamline the loading procedure and minimize errors. Additionally, every lot is tested on the Selectra family of instruments for assured consistency and dependable results from lot to lot.
For consistent, accurate, and reliable results on the ELITechGroup Selectra Family of instruments, Selectra System Reagents, Calibrators, and Controls are recommended.
1 International Federation of Clinical Chemistry. IFCC methods for the measurement of catalytic concentration of enzymes part 5. IFCC method for alkaline phosphatase (orthophosphoric monoester phosphohydrolase, alkaline optimum, E.C.220.127.116.11.). J Clin Chem Clin Biochem 1983; 21: 731–48.