ALP optimal range and reference range
Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026
Sera's bands for ALP, which differ for men and women:
- Male: Optimal 45 – 90 U/L (45 – 90 IU/L); sufficient 30 – 129 U/L (30 – 129 IU/L); out of range below 30 or above 129 U/L.
- Female: Optimal 35 – 80 U/L (35 – 80 IU/L); sufficient 30 – 105 U/L (30 – 105 IU/L); out of range below 30 or above 105 U/L.
Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.
All units
| Unit | Applies to | Optimal | Sufficient | Out of range |
|---|---|---|---|---|
| U/L | Male | 45 – 90 | 30 – 129 | below 30 or above 129 |
| U/L | Female | 35 – 80 | 30 – 105 | below 30 or above 105 |
| IU/L | Male | 45 – 90 | 30 – 129 | below 30 or above 129 |
| IU/L | Female | 35 – 80 | 30 – 105 | below 30 or above 105 |
What the evidence says
The acceptable bands are laboratory reference intervals. The upper edges follow Mayo Clinic Laboratories and MedlinePlus (129 U/L in men, about 104 in women); the lower edge of 30 follows the UK range of 30 to 130 used by NHS laboratories, which is not split by sex. Mayo's own lower limits are higher, 40 in men and 35 in women. The optimal bands are functional targets; no published source was found for them. ALP comes from bone as well as liver, so it runs higher in adolescents, in pregnancy and after a fracture, and a raised result with a normal GGT points to bone rather than liver. A persistently low ALP is worth noting because it can reflect hypophosphatasia or zinc deficiency.
Sources
- ALP - Overview: Alkaline Phosphatase, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference interval 40 to 129 U/L in men (19 and over) and 35 to 104 U/L in women (17 and over). Supports the women's upper edge of 105 (close) and a men's upper edge of 129.
- ALP - blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal range 40 to 129 IU/L. Supports an upper edge of 129.
- Liver Function Test Reference Ranges in Normal Pregnancy — Scarborough, Hull and York Pathology Service, York and Scarborough Teaching Hospitals NHS Foundation Trust, 2022 · Laboratory / reference-interval sourceNon-pregnant adult ranges given for comparison: ALP 30 to 130 U/L, ALT 0 to 34, AST 0 to 31, GGT 0 to 38, total bilirubin below 21 µmol/L. Supports a lower edge of 30.
What ALP (Alkaline Phosphatase) measures
An enzyme found in the liver, bones, kidneys, and gut. High levels can point to liver or bone problems, while low levels can hint at nutrient shortfalls.
Part of the standard liver panel but often overlooked. Persistently low ALP can mean a shortage of zinc, magnesium, or B6, while high ALP is worth investigating for liver or bone problems.