What does an elevation of ALP without concurrent GGT elevation typically suggest?

An elevation of alkaline phosphatase (ALP) without a concurrent elevation in gamma-glutamyl transferase (GGT) is commonly indicative of bone pathology. ALP is an enzyme found in various tissues, including the liver and bone. When ALP levels are elevated and GGT, which is more specific to the liver, remains normal, this suggests that the source of the ALP elevation is likely not hepatic in origin.

In conditions such as bone diseases—like Paget's disease, osteomalacia, or metastatic bone disease—the body increases the production of ALP in response to bone turnover or remodeling. Therefore, the isolated rise in ALP points towards an issue within the bones themselves rather than a hepatic or biliary cause.

In contrast, elevations of both ALP and GGT would suggest a problem linked to hepatobiliary pathology, such as cholestasis or biliary obstruction. The lack of increase in GGT provides a valuable diagnostic clue that helps to narrow down the cause of the elevated ALP to the skeletal system rather than the liver or bile ducts.