From the Guidelines
When investigating elevated alkaline phosphatase (ALP) levels, I recommend starting with a comprehensive laboratory workup including liver function tests (AST, ALT, GGT, bilirubin), ALP isoenzymes, calcium, phosphorus, vitamin D levels, complete blood count, and hepatitis serologies, as these tests can help determine if the elevation is hepatic or non-hepatic in origin 1.
Initial Laboratory Workup
The initial workup should include:
- Liver function tests: AST, ALT, GGT, bilirubin
- ALP isoenzymes to fractionate alkaline phosphatase into its liver, bone, and intestinal isoenzyme fractions
- Calcium, phosphorus, and vitamin D levels to assess bone health
- Complete blood count to rule out hematological disorders
- Hepatitis serologies to assess for liver inflammation
Additional Tests
If liver origin is suspected, add imaging studies like ultrasound, CT, or MRI of the liver and biliary system 1. For suspected bone origin, consider:
- Bone-specific ALP
- Parathyroid hormone levels
- Bone imaging studies
Special Considerations
Additional tests may include:
- Thyroid function tests
- Celiac disease antibodies
- Tests for rare conditions like Paget's disease It is essential to interpret abnormal liver blood test results in the context of the patient's past medical history and current medical condition 1. The pattern of elevation with other lab abnormalities helps pinpoint the source and guide appropriate treatment.
From the Research
Labs Indicated for Elevated Alkaline Phosphatase (ALP) Levels
Elevated ALP levels can be an indicator of various conditions, and several labs can be used to diagnose and monitor these conditions. Some of the labs that can be indicated for elevated ALP levels include:
- Liver function tests, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) 2, 3
- Bone-specific alkaline phosphatase (BSAP) to differentiate between bone and liver sources of elevated ALP 4
- Gamma-glutamyl transferase and transaminases to evaluate liver disease 5
- Total bilirubin to assess liver function and diagnose conditions such as Wilsonian acute liver failure 3
- Ceruloplasmin to diagnose Wilson disease 3
- Carbohydrate antigen 19-9 (CA 19-9), lactate dehydrogenase (LDH), and ALP isozymes to diagnose and monitor certain types of cancer 4
Conditions Associated with Elevated ALP Levels
Elevated ALP levels can be associated with various conditions, including:
- Liver disease, such as alcohol-induced hepatitis 5
- Bone metastasis 4
- Certain types of cancer, such as pancreatic and lung cancer 4
- Hypophosphatasia (HPP), a rare inherited disorder 5
- Wilsonian acute liver failure in children 3
- Symptomatic hemorrhagic transformation in ischemic stroke patients with atrial fibrillation and/or rheumatic heart disease 6