Endocrine Abstracts

Introduction: Hypercalcaemia during pregnancy poses a risk to both the mother and foetus and can present a complex management issue. Although hypercalcaemia from any cause can occur during pregnancy, primary hyperparathyroidism is the most common cause but other rarer cause such as familial hypocalciuric hypercalcaemia (FHH) should be ruled out. Although usually posing no risk to the mother, infants of mothers with the disease are at risk for neonatal hypocalcaemia, and seizures or tetany.

Case: A 27-year-old Asian lady primigravida and 12 week pregnant was admitted to Obstetrics ward with hyperemesis and poor oral intake. Initial investigations showed mild acute renal impairment and hypercalcaemia, serum calcium 3.35 mmol/l (2.10–2.58) with normal alkaline phosphatase. Her calcium remained high even after the fluid replenishment. Further investigations revealed elevated PTH of 7.3 pmol/l (1.1–4.2), and reduced urinary calcium excretion, 2.4 mmol/24 h urine collection (2.5–6.2), in keeping with FHH. Her thyroid function was normal. On further enquiry and reviewing notes from the previous hospital it became clear that she had hypercalcaemia at the age of 14. She had numerous admissions following that and was diagnosed at that hospital as benign hypocalciuric hypercalcaemia (confirmed by genetic analysis). Her calcium varied from 2.70–3.35 mmol/l. She had previous DEXA scans which did not show any evidence of osteoporoses. She was monitored though out the pregnancy and the antenatal period was uneventful. An elective caesarean section was performed at 38 weeks gestation, and a healthy girl was delivered. Clinical course during puerperium was normal. The neonate was closely monitored for hypocalcaemia and tetany. However her investigations showed hypercalcaemia, 2.80–2.83 mmol/l, which was persistent even after 4 weeks. Further investigations revealed inappropriately high PTH and low urinary calcium excretion, consistent with FHH. Genetic testing for FHH is being arranged.

Comment: FHH is an autosomal dominant disorder due to heterozygous inactivation of the calcium sensing receptor gene. Because maternal hypercalcaemia may lead to foetal parathyroid suppression, neonatal hypocalcaemia would be expected. In our case, the baby has supposedly inherited the gene and hence there was no hypocalcaemia.