ALP Isoenzymes (ALP Isoforms)
| Category | Biochemistry >> Proteins |
|---|---|
| Test background |
The alkaline phosphatases are zinc metalloproteases expressed in most tissues of the body, at particularly high concentrations in intestinal epithelium, kidney tubules, bone (osteoblasts), liver & placenta. Their precise function in vivo is not known, but it is associated with lipid transport in the intestine and calcification in bone. Measurement by isoelectric focusing electrophoresis can determine specific isoenzyme contributions. Serum ALP Isoenzyme measurements are of interest in determining the potential cause of an increased Total ALP result. |
| Clinical Indications |
Pathological causes are primarily associated with hepatobiliary and bone (associated with increased osteoblast activity) disorders. Other causes of increased isoenzyme fractions may include physiological bone growth, benign transient hyperphosphatasaemia (BTH), malignant disease, pregnancy, diabetes, gastrointestinal conditions and CRF. Routinely ALP isoenzymes should only be requested if there is an unexplained high concentration of total ALP. |
| Reference range | ALP Isoenzymes is a semi-qualitative test with interpretation provided. The relative contribution of any rare ALP isoforms (e.g. macro isoforms) is provided as part of the report. |
| Sample & container required | Serum (samples containing EDTA, Citrate or Oxlate are NOT suitable) |
| Sample volume | 100 µL (all samples require total CK measurement: if referring from another laboratory please ensure that there is sufficient sample or you have provided your laboratory result on the request form). |
| Transport storage | Stable at 2-8°C for 72 hours. Please freeze pending dispatch for analysis. Sample can be sent by first class post. |
| Turnaround time | 2 week |
| Notes | Please include Total ALP and gGT results on request form if available. Specimens containing inhibitors of alkaline phosphatase activity e.g. heparin, EDTA, citrate, fluoride or iodoacetate are unsuitable. |