Parathyroid Hormone and Breastfeeding

Summary of use during lactation

Because parathyroid hormone is a large protein molecule, the amount in milk is likely to be very low.[1] It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal.[2] Evidence from one case indicates no harm to the breastfed infant with maternal recombinant human parathyroid hormone (1-84). Monitor breastfed infants for signs and symptoms of hypercalcemia or hypocalcemia. Serum calcium monitoring should be considered.

Drug levels in milk and infant serum

Maternal Levels. Relevant published information was not found as of the revision date. Infant Levels. Relevant published information was not found as of the revision date.

Effects in breastfed infants

A woman with hypoparathyroidism was taking recombinant human parathyroid hormone (1-84) and became pregnant. She stopped the drug at 5 weeks of gestation and the calcium dose was increased to 3500 mg daily and calcitriol 1 mcg daily in divided doses was started. At 12 weeks of pregnancy, her calcitriol dose was increased to 1.5 mcg daily and it remained at this dose for the remainder of pregnancy. She restarted parathyroid hormone postpartum at a dose of 75 mcg daily, discontinued calcitriol and her calcium dose was reduced to 500 mg daily. At 3 months postpartum, her parathyroid hormone dose was reduced to 50 mcg daily. She breastfed (extent not stated) her infant for 6 months. The infant’s calcium levels were in the high normal range for her first 8 weeks of breastfeeding, but that could have been caused by the mother’s intake of calcitriol during pregnancy. At 4 years and 5 months of age the child was healthy and meeting developmental milestones.[3]

Effects on lactation and breastmilk

Relevant published information was not found as of the revision date.

References

1. Stratigakis A, Paty D, Zou P, et al. A regression approach for assessing large molecular drug concentration in breast milk. Reprod Breed 2023;3:199-207. doi:10.1016/j.repbre.2023.10.003
2. Anderson PO. Monoclonal antibodies during breastfeeding. Breastfeed Med 2021;16:591-3.33956488 PubMed
3. Liao EP, Cusano NE. Use of rhPTH(1-84) for hypoparathyroidism during early pregnancy and lactation. Endocrinol Diabetes Metab Case Rep 2023;2023:22-0401.37335755 PubMed