Thyroid and Parathyroid Disease During Pregnancy

Pregnancy has a profound, though reversible, effect on the thyroid gland and its functions. As thyroxin is essential for fetal neuro-development, it is critical that maternal delivery of thyroxin to the fetus is ensured early in gestation. Pregnant women require additional iodine intake; a daily intake of 250 μg has been recommended in pregnancy. Uncorrected thyroid dysfunction in pregnancy has adverse effects on fetal and maternal well-being and may also affect neuro-intellectual development in the early life of the child. During pregnancy, close monitoring of calcium (Ca) is necessary, and frequent adjustments in the dose of Ca and calcitriol may be required in order to avoid both hypocalcemia and hypercalcemia, both of which impact fetal parathyroid gland development and may result in maternal and fetal morbidity. Maternal hypocalcemia may result in fetal secondary hyperparathyroidism, which may be associated with demineralization of the fetal skeleton and development of intrauterine fractures. Inadequate treatment of hypoparathyroidism may also result in uterine contractions and increased risk of miscarriage. Calcium, calcitriol, and vitamin D supplements are safe during pregnancy. Mild hyperparathyroidism can be treated conservatively, but in severe hypercalcemia, parathyroidectomy is indicated, preferably in the second trimester.