Endocrine Abstracts

Primary hyperparathyroidism (PHP) can be isolated or a part of MEN especially in the younger patient. We report a 20-year lady presenting in early July-08 with vomiting, abdominal pain and general ill-health. On admission she was pale and dehydrated, with Hb 10.1 g/dl, urea 9.1 mmol/l, creatinine 105 μmol/l, alkaline phosphatase 1568 μ/l (30–130 μ/l) and adjusted calcium 3.92 mmol/l. Her sister reportedly has been investigated in a different hospital for PHP. She was initially treated with intravenous fluids followed by intravenous pamidronate on two separate occasions. Her iPTH was 2145 pg/ml (10–70 pg/ml), with normal cortisol, prolactin and gonadotrophin levels. Erosions of acromioclavicular joints were noted on a chest radiograph and an ultrasound examination of the renal tract showed extensive nephrocalcinosis with diffuse renal disease. Although an ultrasound failed to show any evidence of parathyroid hyperplasia or adenoma, the Technetium MIBI scan suggested an ectopic parathyroid adenoma in the midline of the superior mediastinum at the level of sternal notch. An OGD showed gastritis and she was treated with PPIs. Management was complicated by the patient discharging herself from hospital on multiple occasions and her reluctance to have intravenous fluids and investigations.

As she remained hypercalcaemic despite pamidronate and intravenous fluids, she was started on cinacalcet 30mg od in an attempt to lower and keep the calcium stable before surgery.

Her perioperative calcium levels remained stable and she underwent a parathyroidectomy (PTX). Post operatively, although the calcium levels dropped to below 2 mmol/l, she escaped the anticipated pronounced ‘hungry bone disease’.

Cinacalcet is an allosteric modulator of the calcium-sensing receptor (CaR) on the parathyroid cell surface. It increases CaR sensitivity thereby reducing PTH secretion and serum calcium levels. It is currently licensed for treatment of PHP where surgery is not appropriate. This case demonstrates how cinacalcet may be useful in the perioperative management of difficult cases of PHP by allowing control of plasma calcium and rendering safe PTX possible.

References:
1. Shoback DM et al. The calcimimetic cinacalcet normalizes serum calcium in subjects with primary hyperparathyroidism. J Clin Endocrinol Metab 2003 88 5644–5649.

2. Falchetti A et al. A patient with the MEN1-associated hyperparathyroidism, responsive to cinacalcet. Nat Clin Pract Endocrinol Metab 2008 4 (6) 351–357.