Oral contraceptives, norethindrone and mestranol: effects on tissue levels of minerals

The study involved three levels of dietary zinc (deficient, marginal, and adequate) and four hormonal conditions; namely, no steriods, norethindrone, mestranol, and norethindrone plus mestranol. The steroids were incorporated into diets and fed to 11-wk-old female Sprague-Dawley rats. After 10 wk of treatment, various tissues were excised for mineral assays by atomic-absorption spectrophotometry. Both steroids, reduced weight gain. Mestranol depressed plasma zinc, tibia copper and magnesium, and liver iron, but elevated the zinc levels in liver and erythrocytes, plasma copper, liver magnesium and calcium, and iron content of tibia and heart. In general, the effect was most prominent with adequate zinc but diminished in magnitude with the reduction of zinc intake. In addition, norethindrone increased heart iron and tibia calcium. Mestranol appeared to be the main causative factor and may have induced a possible shift of minerals from one pool to another. As expected, zinc deficiency resulted in the reduction of zinc concentrations of plasma, tibia, kidney, and pancreas, and the elevation of copper, iron, magnesium, and calcium concentrations of various tissues.