Alkaline Phosphatase (ALP)
Alkaline Phosphatase (ALP) is an enzyme found in various tissues of the body, mainly in the liver, bones, kidneys, and bile ducts. The ALP test is used to assess the condition of these organs and detect pathologies.
Main causes of elevated ALP levels:
- Liver diseases: hepatitis, cirrhosis, liver cancer, liver metastases, bile duct obstruction (e.g., gallstones, mechanical jaundice).
- Bone diseases: Paget’s disease, osteomalacia, rickets, osteosarcoma, bone metastases, fracture healing.
- Physiological causes: active growth in children and adolescents, pregnancy (especially 2nd-3rd trimester).
- Other conditions: severe infections, mononucleosis, kidney or lung infarction, hyperparathyroidism, certain medications.
Normal ALP values
Normal ranges depend on age and sex:
- 18–30 years: men 40–130 U/L, women 35–120 U/L
- 31–45 years: men 40–120 U/L, women 35–115 U/L
- 46–60 years: men 40–110 U/L, women 35–110 U/L
- 60+ years: up to 150 U/L for both men and women
Children have higher normal values due to active bone growth; infants and adolescents may have significantly elevated levels.
Causes of decreased ALP
Low ALP levels are rarer and may be associated with magnesium or zinc deficiency, protein malnutrition, hypophosphatasia, and thyroid disorders.
Diagnostic significance
Elevated ALP indicates damage to the liver, bile ducts, or bones. To clarify the cause, additional tests such as bilirubin, ALT, AST, calcium, and phosphorus are often performed. Concurrent elevation of ALP and GGT suggests a biliary origin of the pathology.
Thus, the ALP test is an important marker for diagnosing diseases of the liver, bones, and bile ducts, taking into account the patient’s age and physiological characteristics.