An ALP level that is two times the GGT is suggestive of what condition?

When the level of alkaline phosphatase (ALP) is significantly elevated—specifically, at least twice the level of gamma-glutamyl transferase (GGT)—it strongly indicates that the source of the elevated ALP is likely from the bone rather than the liver. This is because GGT is an enzyme that assists in differentiating liver-derived ALP from bone-derived ALP; a high ALP level in conjunction with a normal GGT suggests a skeletal origin.

In conditions such as bone disease or malignancy (like Paget's disease, osteosarcoma, or metastatic bone disease), the ALP levels can become markedly elevated due to increased bone turnover or metabolic activity. The significantly lower level of GGT in this context helps to rule out liver pathology as the primary source of the enzyme, thus reinforcing the interpretation that this elevation indicates an underlying bone disease or malignancy rather than liver disease or obstructive jaundice, where both enzymes would typically be elevated.