We discuss the case of a 41-year-old female gravida 6 para 5 referred to a tertiary hospital at 11 weeks gestation with severe hypercalcaemia. Presenting symptoms included nausea, polydipsia, chest pain and constipation. Past medical history was unremarkable but family history was positive for breast cancer. Her only regular medication was Vitamin D.
Pathology demonstrated a corrected Calcium of 4.18mmol/L and a Phosphate of 0.63 mmol/L. A parathyroid hormone level of 28.4pmol/L confirmed the diagnosis of primary hyperparathyroidism. 4D CT with body shielding found a 34x25mm left inferior parathyroid mass.
Management was initiated with aggressive intravenous fluids, obstetric and cardiology reviews. Despite 72 hours of fluid resuscitation, the corrected calcium remained above 3.5mmol/L and the patient developed fluid overload and hypertension. She received intravenous calcitonin infusions for 3 days - 600mg in 500mL saline over 6 hours. The corrected calcium dropped from 3.52mmol/L to 2.99mmol/L following 24 hours of the calcitonin infusion. The nadir level was 2.81mmol/L, two days after the first calcitonin dose. It then rose to 3.26 mmol/L requiring a further infusion.
She underwent a parathyroidectomy at 12 weeks gestation to remove a large left inferior parathyroid adenoma. She was monitored for hungry bone syndrome and was stable on oral Caltrate and Vitamin D. The foetus was small for gestational age (5th centile). She had induction of labour and vaginal delivery at 39 weeks gestation.
This case demonstrates the use of calcitonin as a bridge to parathyroidectomy where there is hypercalcaemia refractory to intravenous fluids. Whilst effectiveness of calcitonin is limited by tachyphylaxis, it is advantageous as it does not cross the placenta1 and provides time until definitive management can occur. In contrast Cinacalcet, which is the preferred agent, is Category C in pregnancy2. Our patient wanted to avoid Cinacalcet and hence calcitonin was used.