Calcium homeostasis and blood pressure regulation in normal and insulin-dependent diabetic pregnancy

• Main Author: Dunlop, Diana Clare
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-1999
• Subjects: Medicine; Obstetrics
• ISBN: 1073252884; 9781073252886

This thesis describes studies performed on normal and IDDM women during and after pregnancy: assessment of dietary calcium;a prospective, randomized, double-blind, placebo-controlled trial on the effect on blood pressure of a daily 1.5g calcium supplement, given from 20 weeks until delivery;a longitudinal study of the short term effects of a standard meal and 1g oral calcium load on calcium homeostasis and plasma renin and substrate concentrations.Results presented show that both groups of women received adequate dietary calcium during pregnancy and that calcium supplementation did not affect blood pressure. Pregnancy-induced changes in blood pressure are different in IDDM women who have no mid-trimester fall. In IDDM, compared with normal pregnancy serum ionized calcium and urinary calcium excretion are identical, serum magnesium does not fall and intact parathyroid hormone concentrations are lower. Phosphate excretion is increased in pregnant and non-pregnant IDDM women.Plasma renin concentration correlates negatively with serum ionized calcium in normal but not IDDM women; during pregnancy renin concentration rises in normal but not IDDM women. Plasma renin substrate rises throughout normal pregnancy, in IDDM pregnancy there is no further rise beyond 20 weeks. These observations suggest impaired synthesis or release of renin in IDDM with additional inhibitory factors acting in IDDM pregnancy.The observed differences between normal and IDDM pregnancy, whilst interesting in their own right, do not suggest a mechanism for the increased incidence of PE in IDDM pregnancies.