Serum alkaline phosphatase elevation in female rats treated with ethinyl estradiol.

Ethinyl estradiol treatment to female rats resulted in increased levels of serum alkaline phosphatase, but was not associated with any other manifestation of toxicity such as increased serum transaminases or toxic lesions. Elevated serum alkaline phosphatase seen in rats treated with chloroform was associated with frank hepatotoxicity. Induction of hepatic drug metabolising enzymes in rats by phenobarbitone treatment did not result in raised serum alkaline phosphatase levels. Estradiol benzoate treatment to rats also did not increase serum alkaline phosphatase levels. Ethinyl estradiol also resulted in increased alkaline phosphatase content in the liver, intestine and bone. The raised intestinal alkaline phosphatase content of rats treated with phenobarbitone or estradiol benzoate was not associated with an increase in the serum levels. There was histochemical evidence of induction of canalicular alkaline phosphatase in the liver in Ethinyl Estradiol treatment. The study of the electrophoretic separation of serum alkaline phosphatase of ethinyl estradiol treated rats revealed the presence of a new fast moving fraction, similar to those seen in bile duct ligated rats. It is concluded that the serum alkaline phosphatase increase during ethinyl estradiol treatment at least in part is from the liver, due to new synthesis.