SAT-232 Is There a Role for Genetic Testing in Guiding the Management of Primary Hyperparathyroidism in Pregnancy?

Abstract

Introduction Primary hyperparathyroidism (PHPT) in pregnancy is rare, with a reported incidence of <1%. It is associated with serious maternal and foetal complications, and is genetically determined in ~10% of cases. Confirming a genetic diagnosis can guide management of inherited PHPT, and enables screening for syndrome-related diseases. This case series highlights the role of genetic testing in the tailored management of patients with PHPT in pregnancy. Clinical cases Case 1 is a 20 year old female who was diagnosed with PHPT at 5 weeks gestation after presentation with nausea. She was hypercalcaemic (2.78 mmol/L at diagnosis; 2.98 mmol/L pre-parathyroidectomy), had negative neck ultrasonography and a MEN1 mutation (exon 2, c.236_237del, p.(Pro79fs)) on genetic testing in pregnancy. After initial management with oral and IV rehydration, her severe symptomatic hypercalcaemia required treatment with open neck exploration and a 3 gland parathyroidectomy in the 2nd trimester. The standard surgical approach of a 3.5 gland parathyroidectomy was avoided due to the risk of inducing hypoparathyroidism. Intra-operative PTH dropped 53.8% post 3 gland parathyroidectomy. Parathyroid hyperplasia on histology was consistent with the diagnosis of MEN1 syndrome. The patient’s symptoms resolved post-operatively and foetal investigations are normal at 28 weeks gestation. She is receiving close obstetric follow-up including 3-weekly foetal growth scans due to the increased risk of IUGR. She was counseled on her increased risk of pancreatic and pituitary tumours and her 1st degree relatives are undergoing genetic screening. Case 2 is a 40 year old female with a known diagnosis of PHPT who was awaiting parathyroidectomy prior to pregnancy. She was hypercalcaemic (2.78 mmol/L at 7 weeks; 2.99 mmol/L pre-parathyroidectomy), and had a lower left parathyroid adenoma on ultrasound and pre-pregnancy SPECT-CT. Genetic testing was not performed as she was 40 at diagnosis and had no contributory family history. After failure of conservative management, parathyroidectomy of the left superior parathyroid gland was performed in the 2nd trimester. Histology results confirmed a left inferior parathyroid adenoma, concordant with the radiological findings. Her symptoms improved post-operatively; she is receiving close obstetric follow-up. Clinical lessons Genetic testing enables the management of PHPT to be tailored appropriately. It can better inform the surgical approach; including the need for subtotal parathyroidectomy and bilateral neck exploration in those cases at risk of multiple parathyroid gland disease, as demonstrated in our case with MEN1. Finally this case series demonstrates that surgical management of PHPT should be considered for select cases in pregnancy and thus far no maternal or foetal complications have arisen in these featured cases following surgical intervention.