Isolated muscular sarcoidosis presenting as hypercalcaemic renal failure.

The case report describes the details of a man in his 40s admitted for evaluation of renal failure. Biochemical testing revealed parathyroid hormone (PTH) -independent hypercalcaemia. The evaluations for the usual causes such as malignancies, granulomatous diseases, multiple myeloma and vitamin D toxicity were negative. Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) scan identified diffuse uptake in the muscles, and the subsequent muscle biopsy showed non-caseating granulomas suggestive of granulomatous myositis, possibly sarcoidosis, in view of raised ACE levels and the absence of other causes. The patient showed a dramatic response to glucocorticoids, with prompt relief of symptoms and normalisation of serum calcium and creatinine. The case highlights the importance of considering sarcoid myositis in the evaluation of hypercalcaemia and the need for prompt initiation of glucocorticoid therapy to achieve favourable outcomes. The successful use of FDG-PET in diagnosing PTH-independent hypercalcaemia suggests its potential as a valuable tool in the diagnostic algorithm for this condition.