Alkaline phosphatase
Also called: ALP, bone-specific alkaline phosphatase, BSAP, bone ALP test, Alkaline phosphatase test
What it means
Alkaline phosphatase (ALP) is an enzyme found in bone, liver, and other tissues; the bone-specific form (BSAP) is made by bone-building cells and used as a marker of bone formation activity.
Your doctor may check ALP to help spot high bone-turnover conditions like Paget's disease or to track bone activity alongside other tests.
Alkaline phosphatase (ALP) is an enzyme made in several tissues, including the liver and bone. The bone-specific form, often called BSAP, is produced by osteoblasts, the cells that build new bone. A blood test for ALP can be a general liver/bone screen, or a bone-specific version can be ordered to look more closely at bone-building activity.
Bone-forming cells make ALP while they're actively laying down and mineralizing new bone matrix. As these cells mature, their ALP activity typically decreases. So ALP levels reflect how much active bone-building is happening at a given moment, which is why doctors sometimes call it a 'bone formation marker.'
Doctors use ALP mainly to help identify or monitor conditions with unusually high bone turnover, such as Paget's disease, where levels can be markedly elevated, or sometimes to track response to treatment. It isn't used alone to diagnose osteoporosis and doesn't replace a DEXA scan. Any unusual ALP result should be discussed with your doctor, who can sort out whether it's coming from bone, liver, or something else.
This enzyme marker helps doctors spot high bone-turnover conditions like Paget's disease and track bone activity.
Where this leads
WordCurious about the condition this marker can flag? See how Paget's disease causes disorganized, weaker bone in specific spots.
Where the Academy teaches it
This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.
Related words
Bone turnover markers (BTMs) are blood or urine tests that measure how fast bone is being broken down and rebuilt…
Bone formation markers are blood tests, like P1NP, that measure how actively osteoblasts are building new bone tissue.
P1NP is a blood marker that shows how fast your body is building new bone collagen right now.
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Paget's disease is a condition where bone remodeling speeds up too much in specific spots, creating new bone that's…
CTX is a blood test marker that shows how fast your body is breaking down old bone right now, acting like a…
Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.
