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.