Alkaline phosphatase normal range: ALP levels by age and sex

Quick answer: the alkaline phosphatase normal range for adults is 40 to 129 U/L (0.68 to 2.19 µkat/L) on MedlinePlus. Mayo Clinic Laboratories uses 40 to 129 U/L for men aged 19 and over and 35 to 104 U/L for women aged 17 and over. Cleveland Clinic notes other labs use 44 to 147 IU/L or 30 to 120 IU/L. Growing children, teens and pregnant women normally have higher ALP.

Track ALP with your other liver markersALP is on SiPhox Heart & Metabolic, GLP Optimization and Ultimate 360, with ALT, AST and bilirubin. $124 a test plus $25 shipping.

See SiPhox panels

Alkaline phosphatase normal range

ALP is reported in U/L (the same as IU/L). Age matters more for ALP than for almost any other routine marker, because bone-building cells make a lot of it during growth spurts.

Source: Mayo Clinic Laboratories. Girls reach adult levels earlier than boys because their growth spurt comes earlier.

What ALP is

Alkaline phosphatase is a family of enzymes. The ACG guideline explains that in the liver it sits on the membrane of liver cells lining the bile channels, and that it is also made in bone, placenta, intestine and kidney. Outside the liver, bone is the most common source. A standard ALP test cannot tell you which organ it came from (MedlinePlus), so the pattern with other markers does that job.

ALP is part of the liver function test and the comprehensive metabolic panel.

What high ALP means

A high ALP usually means either a bile-flow problem in the liver or increased bone turnover. The ACG notes that ALP rises when bile ducts are blocked, even when the blockage is too small to raise bilirubin. MedlinePlus lists these causes:

• Liver and bile ducts: biliary obstruction, hepatitis, cirrhosis, mononucleosis
• Bone: healing fractures, Paget disease of bone, osteomalacia, bone tumors
• Hormones and other: hyperparathyroidism, hyperthyroidism, leukemia, lymphoma, sarcoidosis, heart failure
• Normal causes: growth spurts, pregnancy (placental ALP), and in people with blood type O or B, a fatty meal before the test (intestinal ALP)

What low ALP means

A low ALP is less common. MedlinePlus lists zinc deficiency, protein deficiency and malnutrition, pernicious anemia, thyroid disease, Wilson disease and hypophosphatasia, a rare inherited bone disorder. A single slightly low value in an otherwise healthy adult is rarely a concern, but a persistently low result is worth raising with your doctor.

Worked example: liver or bone?

A 45-year-old woman's ALP comes back at 180 U/L, 1.7 times the Mayo upper limit of 104. The ACG recommends confirming a high ALP with GGT: a raised GGT points to the liver. If her GGT is also high, the next questions are about bile ducts and liver disease. If her GGT is normal and her ALT, AST and bilirubin are normal too, bone is the more likely source, for example a healing fracture.

Compare a 14-year-old boy with an ALP of 380 U/L. That looks alarming against an adult range, but it sits inside Mayo's 116 to 468 U/L for boys aged 13 and 14. Always check the report's age band.

What to test next

Getting a reliable ALP result

• Test fasting if your blood type is O or B. The ACG notes ALP can rise after a fatty meal in these blood types because of intestinal ALP.
• Mention recent fractures and pregnancy. A healing fracture and pregnancy both raise ALP (MedlinePlus), and neither needs a liver workup.
• Use the right age band. Anyone under 19 should be compared with Mayo's age table, not the adult range.
• Stay with one lab. The upper limit is 104 or 129 U/L at Mayo but 147 IU/L at labs using the 44 to 147 range Cleveland Clinic cites. An ALP of 180 is 1.7 times a 104 limit but only 1.2 times a 147 limit, which changes how urgent it looks.

At-home tests that include ALP

ALP is on three SiPhox panels: Heart & Metabolic, Ultimate 360 and GLP Optimization. It is not on Longevity Essentials, Thyroid Focus or Hormone Focus.

Only Ultimate 360 and GLP Optimization also report GGT, so they are the panels that let you run the ACG's liver-or-bone check in one sample. Heart & Metabolic at $149 per test is the cheaper option if you only want to watch ALP over time. SiPhox is a wellness service without doctor review, so discuss an abnormal ALP with your doctor. See our SiPhox review.

A note on home samples: SiPhox's partner lab tests capillary blood collected from the upper arm. SiPhox says its results show a 95% to 99% correlation with venous draws in its own quarterly comparisons against Labcorp and Quest, but it has not published a study of the EasyDraw device. If a result would change a treatment decision, confirm it with a venous test through your doctor.

Heart & Metabolic

$124 + $25 shipping per test

28 biomarkers per test

Lipids plus kidney and liver function: the panel for cardiovascular and metabolic risk.

Check price

Ultimate 360

$249 + $25 shipping per test

62 biomarkers per test

Everything on the four core panels plus iron studies, B12 and folate, GGT and PSA.

Check price

GLP Optimization

$199 + $25 shipping per test

46 biomarkers per test

Built for people on GLP-1 medication: metabolic, liver, kidney, nutrient and iron markers.

Check price

Get ALP and GGT in one drawUltimate 360 covers liver, kidney, lipids, thyroid, hormones and iron: 62 biomarkers per test from the upper arm.

Check SiPhox price

Frequently asked questions