Calcium Chaos in Sarcoidosis: A Tale of Severe Hypercalcemia's Diagnostic Challenge

Sarcoidosis is a systemic inflammatory condition characterized by noncaseating granulomas. Lung involvement is typical, while extrapulmonary manifestations, notably lymphadenopathy, are observed in a significant proportion of cases. The etiology involves complex interactions among immune cells and mediators, resulting in granuloma formation capable of independently producing 1,25-dihydroxyvitamin D, leading to unregulated hypercalcemia and hypercalciuria. Diagnosis can be challenging, especially when hypercalcemia is the initial symptom. The presence of noncaseating granulomas on biopsy is characteristic of sarcoidosis. We present a case of severe hypercalcemia in a 53-year-old woman, initially suggestive of primary hyperparathyroidism due to non-suppressed intact parathyroid hormone (PTH) levels and unilateral intrathyroidal tracer uptake on a technetium 99m sestamibi parathyroid scan. The patient presented with hypertension, acute kidney injury, and severe hypercalcemia. Initial assessment, including a parathyroid scan, hinted at primary hyperparathyroidism. However, further evaluation, including chest computed tomography (CT) and endobronchial biopsy, revealed sarcoidosis with noncaseating granulomas. Prednisone therapy led to normalization of serum calcium and creatinine levels. The case underscores the complexities in diagnosing sarcoidosis, especially when presenting with severe hypercalcemia. Despite non-suppressed PTH and suggestive imaging, the final diagnosis relied on endobronchial biopsy findings. The study highlights the limitations of conventional diagnostic markers, emphasizing the need for a comprehensive and individualized approach.