Alkaline phosphataseALP
An enzyme from the liver and bones, read as part of a liver panel.
Alkaline phosphatase, usually written ALP, is an enzyme found in several tissues, chiefly the bile ducts of the liver and in bone, with smaller contributions from the intestine, kidney and placenta. It appears on standard liver panels for that reason.
Because it comes from more than one place, a raised result is a question rather than an answer. The usual first step is to work out whether it is coming from liver or bone, which is done by looking at gamma GT: raised alongside ALP points to the biliary system, normal points towards bone.
On the liver side it is characteristically raised in conditions obstructing bile flow, such as gallstones, and in certain chronic liver diseases, often with bilirubin and gamma GT moving alongside it.
On the bone side it reflects osteoblast activity, meaning bone formation. That makes it high in perfectly normal circumstances: growing children and adolescents have values well above adult reference ranges, and it rises during fracture healing and in pregnancy.
That growth related elevation is the most common reason a parent sees an alarming number on a child's blood test, and in that context it is expected rather than concerning.
Low ALP is unusual and occasionally meaningful, appearing in zinc or magnesium deficiency, malnutrition and the rare inherited condition hypophosphatasia.
In practice, ALP is a signpost read alongside the rest of the panel, and an isolated mildly raised value in a well adult is often repeated before anything else happens. Persistent or marked elevation is a matter for a GP rather than for interpretation from a website.
Where your own result would sit
Most people reading this page are holding a blood-test report with this marker on it, and the question they arrived with is whether their number is normal. A reference interval says where most results from a healthy population fall; a guideline threshold is where a clinical body draws a line for a decision. Neither is a target, and a result on the wrong side of one is not a diagnosis: the same number can be unremarkable in one person and worth looking into in another, which is why the clinician who ordered the test reads it against your history rather than against a list.
Alkaline phosphatase has no published interval on this page yet. We hold one, and the dashboard draws it beside a reader’s own result, but it has not been read back against the laboratory’s own page since it was collected. A figure printed beside somebody’s blood result has to have been seen at its source, not remembered, so this one waits.
On your own blood test?
Alkaline phosphatase is one of the markers FitTools can read from an uploaded blood-test report. You confirm every value before anything is saved, and your results are explained together in one place.