Heat inactivation is primarily used to distinguish which two types of ALP?

Heat inactivation is used to differentiate between liver alkaline phosphatase (ALP) and bone alkaline phosphatase due to their varying heat stability. When alkaline phosphatase enzymes are exposed to heat, liver ALP is more susceptible to inactivation compared to bone ALP. This property allows clinicians to perform specific tests that can help ascertain the source of increased ALP levels in serum, guiding them in diagnosing liver or bone diseases.

In pure context, if the ALP is heat-treated, the liver isoenzyme will lose its activity, while the bone isoenzyme will remain active. This differential heat stability is leveraged in various laboratory protocols to clarify the origin of the enzyme elevation observed in patient specimens. The other options involve isoenzymes or enzymes that do not exhibit the same distinct heat sensitivity, making them less effective for this specific diagnostic application.