Relevance of serum alkaline phosphatase as a diagnostic aid in lung pathology.

Alkaline phosphatase (ALP, 3.1.3.1) is a dimeric glycoprotein present in humans that catalyses the hydrolysis of orthophosphoric monoesters at alkaline PI! (1). It has been reported to occur in abundance in human bile canaliculi, bone, intestine, placenta and kidney (1). Hence serum ALP levels has been extensively used as a diagnostic tool for hepatobilliary disorders particularly in patients with extrahepatic cholestasis (2). It bas also been suggested to be useful in the diagnosis of malignancies and diseases affecting the liver (3,4), bone (5) and kidney (6). However, in the last few years a number of workers have reported serum ALP as a useful diagnostic parameter in certain types of lung disorders (7-9). In the light of this information available in scientific literature the aim of the present work was to evaluate and confirm the extent of utility of serum ALP as a diagnostic marker for various lung pathology.