The enzyme is found in almost all organs. AP is diagnostically especially significant in diseases of the skeletal and the hepatobiliary system. In dogs, there is also steroid-induced AP, which particularly plays a role in the diagnosis of hyperadrenocorticism (Cushing's disease).
In the context of bone diseases, high levels are present in case of ostitis deformans, which allows to differentiate from osteoporosis. In bone tumours, increases in activity are measured whose extent correlates to the osteoblast activity (very high levels in osteosarcoma, hardly any increases in benign tumours). Rachitis and osteomalacia have elevated levels with decreased calcium levels.
Increased levels may indicate cholestasis.
Young animals: physiological concentration up to 2.5-fold.
Dog: Diagnosis of corticosteroid-induced AP is possible by determining the heat-stable isofraction.
Cattle: The AP level ante partum allows to assess the risk of parturient paresis.