Endocrine Abstracts

A 21-year-old woman with homozygous sickle cell disease, presented to A&E with vomiting and diarrhoea, and was noted to be hypercalcaemic (corrected calcium 3.00 mmol/l [ref. 2.2–2.6]; phosphate 0.48 mmol/l [ref. 0.8–1.5]). She reported polyuria and polydipsia, but no other symptoms of hypercalcaemia. There was no history of renal stones, renal impairment, or fragility fracture. A maternal aunt required parathyroidectomy in middle age. Bloods revealed PTH 138.4 pmol/l (ref. 1.6–6.9), magnesium 0.6 mmol/l (ref. 0.7–11.0), Vit D <13 nmol/l and normal pituitary function. 24-hour urinary calcium was elevated at 9 mmol/day (2.5–7.5). A calcium creatinine clearance ratio of 0.0131 ruled out familial hypocalciuric hypercalcaemia. The hypercalcaemia responded to intravenous fluids and she was discharged on cinacalcet and cholecalciferol. Three days later she represented with a further sickle cell crisis. Bloods showed persistent hypercalcaemia 2.67 mmol/l, with an acute haemoglobin drop from 82 to 58 g/l (ref. 120–150). The patient was transfused and restarted IV fluids. Following transfusion, hypercalcaemia worsened, peaking at a level of 3.77 mmol/l, refractory to IV fluids, withdrawal of cholecalciferol, and an increase in cinacalcet dose, but responded to IV bisphosphonates. Admission was compounded by a delayed haemolytic transfusion reaction. Localisation studies were performed: there was no abnormal parathyroid tissue on neck ultrasound, but CT and Tc99m-sestamibi scanning both suggested a 4.4 cm upper mediastinal parathyroid mass. Emergency parathyroidectomy was planned, but postponed when pre-operative COVID-19 screening returned a positive nasal swab. Surgery was further delayed by an admission with hyperhaemolysis, but was performed 4 weeks later. The post-operative course was complicated by severe, symptomatic hypocalcaemia, and sickle chest crisis. Imaging was consistent with COVID-19 pneumonia, despite a then negative nasal swab. Management of hypocalcemia with IV calcium infusions worsened the degree of haemodilution and increased the potential for precipitating a crisis. Conversely, blood transfusion increased the risk of hyperhaemolysis. Hungry bone syndrome is likely to underly the intractable hypocalcaemia, which was exacerbated by vitamin D deficiency. Additionally, COVID-19 pneumonia increased the risk of precipitating a crisis. Histology was in keeping with an atypical parathyroid adenoma, with scattered mitoses and a Ki-67 of 20%.

Discussion: – Role of vitamin D replacement in hyperparathyroidism.

– Concerns about malignancy in a young patient with very elevated calcium and PTH.

– Complications of GA, surgery, and post-operative calcium replacement in sickle cell patients.

– Surgical planning in times of COVID-19 and dealing with COVID-19 sequelae.

– Role of genetic studies.