A 39-year-old woman presented at 23 weeks gestation with extreme fatigue and non-specific neurological symptoms. Other than mild hypertension her physical examination was normal. Serum calcium was 3.36 mmol/l (normal 2.122.62) and phosphate 0.8 mmol/l (Normal 0.81.5). She was severely hypercalcemic throughout pregnancy and her corrected calcium ranged between 2.82 and 3.48 mmol/l. Other investigations included 25 hydroxy-Vitamin D3 98 (normal 75200), undetectable PTH <1.2 pmol/l (normal 1.66.9) confirmed by two laboratories, 1,25 dihydoxy-Vitamin D 209 pmol/l (normal value for pregnancy) and an inappropriately normal PTH related peptide level of 1.3 pmol/l (normal range 0.71.8 pmol/l). The serum angiotensin-converting enzyme and serum protein electrophoresis were normal.
A trial of steroids and intravenous fluids did not affect the hypercalcaemia. In view of poorly controlled hypertension and proteinuria she had caesarean delivery at 36 weeks. Both she and her male neonate were hypercalcemic at delivery but this fully resolved within 24 h, suggesting a placental aetiology of the hypercalcaemia. Regrettably the placenta was inadvertently discarded after delivery.
The literature suggests that the physiological changes in placental and mammary PTH related peptide production observed in pregnancy and the peripartum period might play a significant role in calcium homeostasis in both the mother and foetus. This may be independent of other calcitrophic hormones including parathyroid hormone and calcitriol.
Parathyroid hormone related peptide hypersecretion in pregnancy is a rare entity and this has only very rarely been described. We believe this severe form of hypercalcaemia in both the mother and neonate was precipitated by an overproduction of PTH related peptide by the placenta. This case demonstrates the diagnostic and therapeutic challenges posed by this very rare but potentially life-threatening pregnancy related condition.