Endocrine Abstracts

Current guidance recommends replacing vitamin D in patients with mild primary hyperparathyroidism although there are reports of worsening hypercalcaemia in some patients. Vitamin D replacement has also been known to cause hypercalcaemia in patients with sarcoidosis. We present a case of a patient with co-existent sarcoidosis and primary hyperparathyroidism, who developed severe hypercalcaemia following treatment with high dose Vitamin D.

A 63 year old lady presented to hospital with symptomatic hypercalcaemia. Her admission calcium levels were 3.59 mmol/l with mild acute renal impairment (creatinine 132 umol/l, eGFR 37 ml/min). PTH level was 2.0.

Her past medical history included pulmonary hypertension secondary to chronic venous thromboembolism. Two months previously she was admitted for a fractured neck of femur and found to have Vitamin D levels < 12.5 nmol/l. She was treated with high dose vitamin D replacement followed by maintenance therapy. Blood tests prior to this treatment had shown a Calcium level of 2.73 mmol/l, coincidental with a PTH of 10.6 pmol/l.

She was initially treated with IV fluids and IV pamidronate but despite this her calcium levels failed to decrease significantly. A CT scan showed mediastinal and abdominal lymphadenopathy, unchanged since a previous scan the year before. Subsequent review of her medical notes and previous investigations found that she had had a lymph node biopsy 6 months beforehand which had shown features of sarcoidosis, which her previous team had been unaware of.

Steroid treatment was commenced for sarcoid-associated hypercalcaemia and calcium levels returned to normal within 5 days of this. A parathyroid MIBI scan showed a likely parathyroid adenoma. There was biochemical evidence of primary hyperparathyroidism from 3 years before these recent clinical events suggesting she had co-existing primary hyperparathyroidism and sarcoidosis.

This case highlights the need to monitor calcium levels closely in patients with primary hyperparathyroidism or sarcoidosis who are receiving vitamin D replacement.