Changes in serum calcium and treatment of hypoparathyroidism during pregnancy and lactation: A single-center case series.

BACKGROUND Hypoparathyroidism (Hypo-PT) is rare, and studies on Hypo-PT, especially during pregnancy and lactation, are limited. DESIGN AND SETTING This was a retrospective study on a relatively large case series in a single center from mainland China. METHODS A total of 19 patients with 25 pregnancies, diagnosed with Hypo-PT before pregnancy, were enrolled. Data on clinical characteristics and treatment strategies at onset time and around pregnancy period were collected. RESULTS During pregnancy, except two patients with missing data, five patients with six pregnancies (6/23, 26.1%) experienced improved Hypo-PT condition, defined as an increased serum calcium level; four patients with four pregnancies (4/23, 17.4%) experienced worsened Hypo-PT condition, defined as a more than 0.2 mmol/L decline in the serum calcium level; and three patients with three pregnancies (3/23, 13.0%) remained in stable Hypo-PT condition. The prevalence of adverse pregnancy outcomes was 30.4% (4/23 for preterm delivery; 3/23 for miscarriage). The serum Ca and 24-hUCa levels significantly increased during lactation compared with pregnancy (2.57 ± 0.34 vs 1.99 ± 0.11 mmol/L, P < 0.001; 12.28 ± 5.41 vs 8.63 ± 3.22 mmol/L, P = 0.013), and five patients with five lactations (5/12, 41.7%) developed hypercalcemia in the first 2 months after delivery. CONCLUSIONS Female patients with Hypo-PT had different changes in calcium homeostasis and a high prevalence of adverse outcomes during pregnancy. Thus they should be monitored closely to maintain the optimal serum Ca level. Decreasing drug dosage during the lactation period should be considered to avoid hypercalcemia.