A Raised ALP with a Normal GGT
Alkaline phosphatase comes from two main places, the liver and bone, and the panel does not say which. GGT does. It rises with the liver and ignores bone entirely, so a raised ALP sitting beside a normal GGT moves the source to bone and makes the liver an unlikely one.
The pattern on your report
- ALP High · moderate Key
- GGT Normal Key
- ALT Normal Key
- Bilirubin Normal Key
- Calcium Normal Supporting
Printed as: ALT in U/L— Older reports print it as SGPT.ALP in U/L— One notation, but reference ranges differ sharply by age and by assay method, so the range printed beside the result matters more than usual.Calcium in mmol/Lor mg/dLGGT in U/L— Labeled GGT, gamma-GT or GGTP depending on the report.Bilirubin in umol/Lor mg/dL
Why the numbers look like this
The same enzyme activity is produced by different tissues as slightly different isoenzymes, and a routine panel measures them together as one number. Bone-derived ALP comes from osteoblasts, the cells that build bone, so it rises whenever bone is being remodeled quickly: during growth, while a fracture heals, and in conditions where turnover is abnormally high.
GGT lives in the cells lining the bile ducts and nowhere near bone. Because both enzymes rise together when the problem is biliary, and only ALP rises when the problem is skeletal, the pair works as a simple source test.
The most common version of this is not a disease at all. In a growing teenager, ALP can run at several times the adult upper limit purely because bone is being laid down fast, and it settles on its own once growth finishes.
Not being flagged is not the same as normal
Adult reference ranges sit somewhere near 30 to 130 U/L depending on the laboratory and the method, but age is what makes this test unusual: children and adolescents have their own much higher ranges, and a teenager's result compared against an adult range will look alarming and mean nothing. Pregnancy has the same problem for a different reason, because the placenta makes its own alkaline phosphatase in the third trimester.
What else on the report can hide this
Calcium, phosphate and vitamin D are the three that usually explain a bone-source rise in an adult. Vitamin D deficiency severe enough to cause osteomalacia raises ALP with a low or low-normal calcium and phosphate, and it is both common and fully treatable.
If those come back normal and the rise persists, the question becomes which bones. A markedly raised ALP with normal calcium in an older adult raises Paget disease, which is localized, slow and treatable. A raised ALP with a raised calcium in someone with a known cancer is a different and more urgent situation, and there the calcium is doing the talking rather than the ALP.
GGT is a good guide and not a perfect one: a few liver and bile duct causes leave it flat, so a rise that persists with the bone tests all normal still earns a liver look rather than a shrug.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
Normal growth — in children and adolescents
Bone being built quickly. The result should be read against an age-specific range, and against an adult range it looks dramatic and means nothing. Toddlers occasionally show a transient, very high ALP with nothing wrong at all, which settles within months.
- Very common
Pregnancy — in the third trimester
The placenta produces its own alkaline phosphatase. GGT stays normal, and the rise resolves after delivery.
- Common
Vitamin D deficiency and osteomalacia
Softening of bone from prolonged vitamin D deficiency. Calcium and phosphate sit low or low-normal, there is often bone or muscle aching, and treatment corrects it.
- Common
A healing fracture
Rises for weeks to months after a break, sometimes after one that was never noticed. The history explains it.
- Common
Paget disease of bone — in older adults
Often a markedly raised ALP with entirely normal calcium and no symptoms. Frequently found by accident, localized to a few bones, and treatable.
- Uncommon
Overactive thyroid or parathyroid, or long-standing kidney disease
All three raise bone turnover, the kidney by driving the parathyroid secondarily. Check thyroid function, calcium with PTH, and the creatinine.
- Uncommon
Bone metastases
Suspected with bone pain, weight loss, a known cancer, or a raised calcium alongside. The pain is typically worse at night and not relieved by rest.
- Rare
Benign familial hyperphosphatasemia
A harmless inherited elevation present for life. Recognized by old results showing the same value and by a family history, and it is a reason not to keep investigating.
What is usually checked next
- Calcium, phosphate and vitamin D Identifies osteomalacia, which is the common treatable cause, and starts the parathyroid question if the calcium is off.
- ALP isoenzymes, or a bone-specific ALP Confirms the source directly when the GGT has not settled it, though it is not available everywhere.
- Your previous ALP results Distinguishes a lifelong elevation from something new, and separates a growth-related rise from a persistent one.
- TSH and PTH Covers the two endocrine drivers of high bone turnover.
- Imaging of any painful area Paget disease and metastases both show characteristic changes, and imaging is directed by where it hurts.
When to seek care sooner
- Same day A raised ALP with a raised calcium
- Same day Unintentional weight loss, or a known cancer with new bone pain
- Same day Itching without a rash, or yellowing of the eyes, at any point
- Soon Bone pain that is worse at night or not relieved by rest
- Soon A fracture from a minor injury
- Soon New deafness, headache, or a change in the shape of the skull or a limb
Questions worth bringing to your appointment
- My GGT is normal. Does that mean this is coming from bone rather than my liver?
- Have my calcium, phosphate and vitamin D been checked?
- Do my older results show the same ALP?
- Given my age, is Paget disease worth considering?
- Is a bone-specific ALP available if the source is still unclear?