Primary hyperparathyroidism occurs rarely during pregnancy. The morbidity associated with primary hyperparathyroidism during pregnancy is substantial, with complications reported in up to 67% of affected mothers and 80% of fetuses and neonates, usually in the presence of severe hypercalcemia.
• How should levels of parathyroid hormone (PTH) and vitamin D be interpreted in a pregnant woman with hypercalcemia?
PTH levels are typically in the low-to-midnormal range during pregnancy. A normal PTH level in a pregnant woman with hypercalcemia is consistent with primary hyperparathyroidism. Although an elevated level of 1,25-dihydroxyvitamin D is a recognized cause of hypercalcemia in nonpregnant patients with certain neoplastic or granulomatous disorders (e.g., lymphoma, sarcoidosis, or tuberculosis), in pregnant patients, the elevated level may simply reflect the physiological increase in 1,25-dihydroxyvitamin D during normal pregnancy.
• What are the complications associated with hyperparathyroidism during pregnancy?
Fetal complications associated with maternal hyperparathyroidism include restriction of intrauterine growth, low birth weight, preterm delivery, stillbirth, miscarriage, and neonatal tetany. The maternal complications are similar to those seen in nonpregnant women and include nephrolithiasis, pancreatitis, bone disease, changes in mental status, and hypercalcemic crisis.
Morning Report Questions
Q: How should severe hyperparathyroidism in pregnancy be managed?
A: Parathyroidectomy is the only definitive therapy and is generally recommended for cases of symptomatic and severe hypercalcemia. The second trimester is generally preferred for surgery, but for patients in whom medical management is ineffective, surgical intervention may be necessary irrespective of the gestational age.
Q: How can the success of a parathyroidectomy be determined intraoperatively?
A: Intraoperative PTH monitoring takes advantage of the short half-life of PTH in plasma (3 to 4 minutes) and the availability of a rapid assay for PTH. A reduction in PTH levels of more than 50% is considered to be an indicator of successful removal of the adenoma. Postoperative monitoring of this patient’s serum calcium levels should be continued.