Background
Hypercalcaemia is a common endocrinology issue that requires thorough investigation to identify its cause. Sarcoidosis, a multisystem granulomatous disorder of unknown aetiology, is an infrequent cause of hypercalcaemia. We present a case of PTH-independent hypercalcaemia complicated by an acute kidney injury, requiring extensive work-up to establish a diagnosis. Our patient had a significant background of multiple sclerosis previously managed with alemtuzumab, a monoclonal antibody against CD52.
Case
A 63 year old female with relapsing remitting multiple sclerosis previously managed with alemtuzumab presented with confusion and malaise. Assessment was consistent with hypovolaemia while investigations revealed hypercalcaemia (corrected calcium 3.34mmol/L) and an acute kidney injury (creatinine 153µmol/L, eGFR 33ml/min). Acute management included fluid resuscitation and intravenous pamidronate. PTH was 1.2pmol/L, Vitamin D was 54nmol/L, 1,25-dihydroxyvitamin D was elevated at 282pmol/L and serum ACE was elevated at 181units/L. CT imaging demonstrated extensive paratracheal and subcarinal lymphadenopathy. A renal biopsy demonstrated nephrocalcinosis. A bronchoscopy with endobronchial ultrasound guided transbronchial needle aspiration was performed with histopathology identifying non-necrotising granulomatous inflammation. Sarcoidosis was diagnosed, likely secondary to previous alemtuzumab treatment. The patient was commenced on oral prednisolone 10mg twice daily following a rise in serum calcium.
Discussion
Alemtuzumab is an important management option for relapsing remitting multiple sclerosis but its use is complicated by potentially serious adverse reactions, including thyroid autoimmunity.1 Hypercalcaemia and sarcoidosis are not listed complications of alemtuzumab however, there have been five reported cases suggestive of this. Pulmonary and ocular manifestations of sarcoidosis have been documented in case reports in patients with multiple sclerosis and previous alemtuzumab treatment.2,3 Respiratory symptoms and mild hypercalcaemia attributed to sarcoidosis have been documented in a patient with mycosis fungoides treated with alemtuzumab.4 Our patient’s presentation is highly suggestive of alemtuzumab precipitated sarcoidosis resulting in hypercalcaemia, with both radiological and pathological evidence of sarcoidosis.