Alkaline phosphatase isoenzymes
Blood test Alkaline phosphatase isoenzymes from serum
Blood sample should be taken on an empty stomach (after about 12 hours of fasting).
Alkaline phosphatase isoenzymes blood test (AF differentiation)
Want to know where an elevated alkaline phosphatase (AF) comes from? The alkaline phosphatase isoenzyme test (ELPHO) differentiates between different sources in the body, such as liver, bones, intestines and placenta.
This blood test is used when the total alkaline phosphatase is elevated and the cause is still unclear. This differentiation allows a more targeted search for underlying disorders.
Caution! This test immediately only the iso enzymes (see image) and not the alkaline phosphatase.
What does this test measure?
The test breaks down total alkaline phosphatase into different isoenzymes:
- Liver (hepatobiliary)
- Bone
- Intestine (intestinal)
- Placenta
This reveals which organ or tissue is responsible for the elevated value.
When is this test useful?
This test is recommended for:
Elevated alkaline phosphatase with no obvious cause
Suspicion of liver or bile duct problems
Possible bone abnormalities or increased bone activity
Unclear symptoms requiring differentiation
Significance of abnormal values
Elevated intestinal (bowel) isoenzyme
May occur in:
Blood type B or 0 (especially after meals).
Chronic hemodialysis
Inflammatory diseases of the small intestine
Elevated liver isoenzyme
May indicate:
Liver or bile tract disorders
Cholestasis (bile congestion)
Elevated bone isoenzyme
Seen with increased bone activity, such as:
- Growth phases
- Fractures (healing process)
- Hyperparathyroidism
- Osteomalacia or rickets
- Bone metastases or bone tumors
- Myeloma
- Paget's disease
- Elevated placental isoenzyme
Occurs in:
- Pregnancy
- In rare cases with PLAP
This test is usually performed only after an elevated total alkaline phosphatase (AF)
Blood sampling should be performed fasting (±12 hours).
Analysis is performed by electrophoresis (ELPHO).
The examination is performed once a week
Additional examination
For a complete picture, we recommend additional determinations:
- Calcium
- Phosphate
- Parathormone (PTH)
- Vitamin D
If something abnormal is found that may require immediate medical follow-up, you will always be called by a doctor or medical professional first.
Blood sampling is available at more than 1,000 locations in the Netherlands.
- - AF bone fraction
- - AF liver fraction (intestine, liver, bile)
- - AF intestinal
- - AF placental
When the level of alkaline phosphatase is not within normal reference values, it is possible that it is caused by
- liver diseases
- bone diseases
- tumors
- pregnancy
- certain medications
This differentiation of an elevated alkaline phosphatase test is done in case of an unclear clinical picture
method used ELPHO
1. Bone AF isoenzyme is elevated in:
Growth phases, osteomyelitis, hyperparathyroidism, fracture, osteomalacia, rickets, bone metastases, osteosarcoma, myeloma,
2. Liver AF isoenzyme increases:
May indicate hepatocellular disease, a disease of the cells of the liver itself. This can have various causes.
3. Intestinal elevated AF isoenzyme: in Blood type B and 0, renal dialysis, inflammatory diseases of the small intestine, cholestasis (a condition in which bile cannot be excreted from the liver into the duodenum. As a result, bile congestion occurs).
4. Placental AF isoenzyme elevates: Human Placental Alkaline Phosphatase (hPLAP) is the biomarker most often elevated in testicular cancer.
Smokers can easily have elevated levels.
This blood draw should be done after 12 hours sober
You must be sober for this test
ELPHO method: Electrophoresis
Runs once a week at the lab, so results may take a little longer.
300326EG
