5'-nucleotidase
A liver enzyme used mainly to answer one question: when the alkaline phosphatase is high, is it coming from the liver or from bone? 5'-nucleotidase rises with liver and bile-duct problems but not with bone activity, so it confirms a cholestatic (bile-flow) source.
What it measures
5'-nucleotidase is an enzyme present in several tissues but, for practical purposes, its usefulness is in the liver and bile system. Its main role is as a confirming test for the source of a raised alkaline phosphatase (ALP). ALP is a very useful liver marker — it rises when bile flow is obstructed (cholestasis), for example from a blocked or diseased bile duct or a liver problem — but ALP also comes from bone, and it rises with normal bone growth, healing fractures, and bone diseases. So a high ALP on its own does not say whether the problem is in the liver or the bone. This is where 5'-nucleotidase (like GGT) helps: it rises with liver and bile-duct disease but is not raised by bone activity. So if the ALP is high and the 5'-nucleotidase (or GGT) is also high, the source is the liver/biliary system; if the 5'-nucleotidase is normal, the raised ALP is more likely to be from bone. It is a targeted confirmatory enzyme rather than a first-line screen, used to interpret an isolated raised ALP.
What a high value can mean
- A liver or bile-duct (cholestatic) source of a raised ALP — the main use; confirms the ALP is coming from the liver, not bone.
- Bile duct obstruction — a blocked or narrowed bile duct (stones, stricture, tumour).
- Cholestatic liver disease — such as primary biliary cholangitis or primary sclerosing cholangitis.
- Liver infiltration or masses — tumours, granulomas.
- Not raised by bone disease — which is exactly what makes it useful.
What a low value can mean
- Normal — the expected result; and importantly, a normal 5'-nucleotidase with a high ALP points the source toward bone rather than the liver.
- A low value has no clinical significance.
When to discuss with a doctor
5'-nucleotidase is a specialist confirmatory test, not a routine one. Its value appears in a specific situation: when the alkaline phosphatase is raised and it is not clear whether the source is the liver or the bone. A high 5'-nucleotidase confirms a liver or bile-duct (cholestatic) cause and directs the work-up toward the biliary system — often with liver imaging to look for an obstruction. A normal result with a high ALP points instead toward a bone source. It is interpreted alongside the other liver enzymes and GGT. Mediora.AI shows 5'-nucleotidase together with alkaline phosphatase, GGT and bilirubin so the liver-versus-bone question is answered in context; the interpretation and any further tests belong with your doctor.