ALP (Alkaline Phosphatase) is a blood test that measures alp (alkaline phosphatase) levels in the blood. Normal range: Adult ALP is typically around 30-110 U/L, but it is naturally much higher in growing children and teenagers and in the third trimester of pregnancy (the placenta makes ALP) — both normal. Because ALP comes from both liver and bone, a raised result needs GGT to tell which source.. It is commonly used to helps diagnose liver disorders, bone conditions, and biliary obstruction..
What is ALP (Alkaline Phosphatase)?
An enzyme found primarily in the liver and bones.
Why is it measured?
Helps diagnose liver disorders, bone conditions, and biliary obstruction.
Normal Reference Range
Adult ALP is typically around 30-110 U/L, but it is naturally much higher in growing children and teenagers and in the third trimester of pregnancy (the placenta makes ALP) — both normal. Because ALP comes from both liver and bone, a raised result needs GGT to tell which source.
Note: Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation.
What Causes High ALP?
High ALP comes from either the liver or the bones. Liver causes are typically cholestatic — blocked bile flow from gallstones, a tumour, or drug reactions — and are confirmed when GGT is also high. Bone causes (with a normal GGT) include Paget's disease, a healing fracture, vitamin D deficiency, an overactive parathyroid, and bone metastases. High ALP is normal in growing children and late pregnancy.
What Causes Low ALP?
Low ALP is uncommon and rarely a concern. It can occur with malnutrition, an underactive thyroid, zinc or magnesium deficiency, and the rare genetic condition hypophosphatasia. It occasionally appears in severe anaemia.
How Often Should ALP Be Tested?
ALP is part of routine liver function tests, so it is measured often. When raised, GGT is added to separate liver from bone origin, and bone-specific or calcium and vitamin D tests follow if a bone cause is suspected. It is monitored in liver, biliary and bone conditions.
Related Blood Markers
ALP is interpreted with GGT (to localise to the liver), bilirubin and ALT/AST in the liver panel, and with calcium, phosphate and vitamin D when a bone source is likely.
Key Facts
- •Category: Vital Organ Functions
- •Unit of Measurement: U/L
- •Test Code: ALP
Related Vital Organ Functions Markers
Albumin
The main protein in blood plasma, produced by the liver.
Learn moreALT (Alanine Transaminase)
ALT (Alanine Transaminase, also written ALAT or SGPT) is an enzyme concentrated in the liver. When liver cells are damaged, ALT leaks into the bloodstream, so it is the single most liver-specific enzyme on a standard Liver Function Test (LFT). It is often interpreted alongside AST, GGT and ALP to build a picture of liver health.
Learn moreAST (Aspartate Transaminase)
AST (Aspartate Transaminase, also written ASAT or SGOT) is an enzyme found in the liver, heart, skeletal muscle and red blood cells. Because AST exists in multiple tissues, it is less liver-specific than ALT. Pathology labs report AST as part of the standard Liver Function Test (LFT) panel.
Learn moreBilirubin
A yellow pigment produced during the breakdown of red blood cells.
Learn moreBUN (Blood Urea Nitrogen)
A waste product filtered by the kidneys.
Learn moreCreatinine
A waste product produced by muscles and filtered by the kidneys.
Learn more