lab metric
Alkaline Phosphatase
Table of contents
Description
Alkaline phosphatase (ALP) is an enzyme found in several tissues—most notably the liver/bile ducts and bone. It’s commonly included in a CMP or liver panel. Because multiple organs can contribute to ALP, the key is determining whether an elevated value is coming from the biliary system (cholestasis) or from bone turnover.
Why it matters
ALP helps clinicians evaluate:
Bile flow and liver health (especially when paired with bilirubin and GGT)
Bone activity (growth, healing, high-turnover states)
What high or low results can suggest (general education)
High ALP: bile-duct obstruction or cholestasis, fatty liver with cholestatic pattern, certain medications; or increased bone turnover (fracture healing, Paget disease). Pregnancy can also raise ALP.
Low ALP: less common; can be seen with malnutrition, hypothyroidism, zinc deficiency, or rare genetic conditions (interpretation is context-dependent).
How it’s usually clarified
Clinicians often interpret ALP alongside GGT (more liver-specific) and other liver enzymes. If ALP is isolated and persistent, additional testing can help localize the source.
Educational only, not medical advice. If ALP is persistently abnormal or accompanied by jaundice, itching, pale stools, or right-upper-quadrant pain, seek clinical evaluation.
Frequently Asked Questions
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