ALTERATIONS OF CALCIUM AND PHOSPHATE-METABOLISM IN PRIMARY HYPERPARATHYROIDISM DURING PREGNANCY

Primary hyperparathyroidism (PHP) is rare during pregnancy and has bee n claimed to be associated with significant increase of neonatal morbi dity and mortality. Whether the well recognized changes in calcium (Ca ) and phosphate (Pi) homeostasis occurring in pregnancy might influenc e the biochemical expression of PHP is unclear. We evaluated biochemic al parameters of calcium and phosphate metabolism in two cases of PHP in pregnancy diagnosed in the third trimester (patient 1) and in the s econd trimester (patient 2). Both patients displayed increase in prote in-adjusted plasma Ca, bone resorption evaluated by the fasting urinar y Ca-to-creatinine ratio, renal tubular reabsorption of Ca, urinary cA MP excretion and decrease in renal tubular reabsorption of Pi. These a lterations were identical to those found in 12 non-pregnant women with PHB. The biochemical expression of PHP did not change after delivery in patient 1. This patient underwent the excision of a 1 g parathyroid adenoma on the 13th day after delivery, which led to normalization of all biochemical parameters. The lowest plasma Ca of the newborn of pa tient 1 was 2.02 mM 72 hours after birth. Thus, the results indicate t hat these two pregnant women with PHP displayed biochemical alteration s of calcium and phosphate metabolism similar to those observed in non pregnant women with primary hyperparathyroidism.