Endocrine Abstracts

Introduction: Coexistence of primary hyperparathyroidism and plasma cell dyscrasias such as multiple myeloma and monoclonal gammopathy of uncertain significance (MGUS) is rare. This can cause diagnostic uncertainty regarding the aetiology and relative contribution of each disorder to hypercalcaemia. We present a series of five individuals with this combination.

Case series: All five patients were referred to the endocrine clinic with hypercalcaemia. The series consists of four women and one man with a median age at diagnosis of only 53.5 years (40–76). Presenting complaints included aches and pains at different sites and constipation (one case); one case had incidental hypercalcaemia. Median calcium level was high at 2.95 mmol/l (range 2.57–3.26; reference value 2.2–2.6 mmol/l), 25 hydroxy vitamin D: 32 nmol/l (range 19–67; reference value 50–150), Parathyroid hormone (PTH) levels: 12.77 pmol/l (range 6.2–18.7; reference value 1.9–6.8). Two patients had evidence of nephrocalcinosis and four had osteopenia on bone density scan (one patient had lytic lesions and no formal bone density assessment). Four patients had confirmed multiple myeloma simultaneously diagnosed with primary hyperparathyroidism, when investigated for hypercalcaemia. The other patient had MGUS. The patient with MGUS had negative ultrasound and radio-isotope scanning for parathyroid adenoma. Of the patients with multiple myeloma, three had localised parathyroid adenomas and two have been referred for surgery. Last patient with multiple myeloma and failed parathyroid adenoma localisation is on Cinacalcet, having declined further investigations or surgery.

Conclusion: Concomitant diagnosis of primary hyperparathyroidism and multiple myeloma is rare in the literature, even though the conditions represent common independent causes of hypercalcaemia. Median age at diagnosis was only 53 years and youngest patient with multiple myeloma was only 40 years, which is earlier than expected with either disorder. Median calcium at presentation was 2.95 mmol/l, which is higher than expected with either disorder. The diagnostic approach should always consider evaluation of the common causes of elevated calcium. A simple screening test inclusive of PTH levels, 25 hydroxy vitamin D, serum protein electrophoresis and either urinary Bence Jones protein or serum free light chains, at the first appointment, could give significant insights into the pathophysiological pathways of elevated Calcium.