Endocrine Abstracts

Hypercalcaemia in pregnancy is associated with foetal (IUGR, miscarriage and preterm delivery), maternal (hypercalcaemic crisis, pre-eclampsia, and hyperemesis) and neonatal complications, with severity of hypercalcaemia correlating with the risk of complications. The true incidence of primary hyperparathyroidism in pregnancy is unknown.

A 32 year old lady (G6 P5) with known MEN 1 and associated primary hyperparathyroidism (peak calcium 3.30 mmol/l) presented to the antenatal endocrine clinic at 12 weeks gestation. Her adjusted calcium was 3.24 mmol/l. She was referred for parathyroidectomy at the local tertiary endocrine/maternity hospital as she was in her second trimester, but because of pre-existing psychological problems she failed to attend on multiple occasions and was lost to follow-up. She re-attended at 29 weeks gestation having been unable to tolerate an OGTT for GDM due to nausea. Having declined transfer, and with ongoing issues with nausea, hypercalcaemia and osmotic symptoms, and considering the high levels of calcium recorded in pregnancy, she was counselled about the use of Cinacalcet and commenced on 30 mg OD with a calcium of 2.90.The dose was titrated up to 30mg TDS slowly with a gradual decline in calcium to 2.77. At 37+1 labour was induced due to IUGR and SGA. The following day a baby (2400 g) was delivered by NVD, with Apgar 10 and 10. Discharge was 24 hours later with no complications, and there have been no issues with the baby to date. Mother was discharged home with Cinacalcet as she was not breastfeeding.

Second trimester parathyroidectomy for primary hyperparathyroidism in experienced hands is the consensus recommendation for pregnancy. Cinacalcet is a calcimimetic drug, lowering PTH levels via the CaSR receptor, that is licensed in Europe for the treatment of primary hyperparathyroidism where surgery is not an option. Studies have efficacy in calcium lowering has been shown in primary hyperparathyroidism and also specifically MEN 1 related. A lack of clinical data means that it is not licensed for use in pregnancy, with current evidence limited to case reports. Animal studies have shown no concerns to date.

MEN 1 associated hyperparathyroidism in pregnancy brings its own challenges including genetic counselling and the question of extent of surgical intervention. To our knowledge this is only the second reported case of the use of cinacalcet for MEN 1 – related primary hyperparathyroidism in pregnancy and adds to the evidence base, though in this case efficacy was only mild.