The effects of low dose norethisterone on biochemical variables in postmenopausal women

Norethisterone 2.5 mg/day was administered to 26 postmenopausal, women (age d 54-79 years) with varying degrees of osteoporosis and with a forearm bone mineral density value more than 2 SD below the young normal mean. Fasting blood and urine samples were collected and radiocalcium absorption measured at baseline and after treatment for a median period of 4 months. There wer e significant falls in serum calcium and its fractions, phosphate, alkaline phosphatase and cholesterol (HDL and LDL), and significant rises in serum chloride and parathyroid hormone. In the urine, there were significant fall s in calcium, sodium and hydroxyproline. These changes were in close agreem ent with our previously reported responses to norethisterone 5 mg/day. We c onclude that norethisterone in a dose of 2.5 mg/day is probably as effectiv e as 5 mg/day in reducing bone resorption in postmenopausal women with low bone density.