Sarcoidosis is a multisystem disorder of unknown origin characterized by the presence of non-caseating granulomas in multiple organs. [1] Although it most commonly affects the respiratory system, with bilateral hilar adenopathy and pulmonary infiltrates being the most common findings, any organ can be involved. Renal involvement is rare and, if present, is due either to hypercalcaemia or granulomatous interstitial infiltration and, less frequently, to glomerulopathies or granulomatous involvement of the renal vasculature and retroperitoneum. [1] This report focuses on the case of a 32-year-old man who presented complaining of nausea, vomiting, fatigue, and a 5 kg weight loss over the past three months. His medical history was unremarkable. Physical examination revealed the presence of generalized lymphadenopathy. Laboratory evaluation showed severely impaired renal function (urea 150 mg/dL, creatinine 4 mg/dL), severe hypercalcemia (13.5 mg/dL) with hypercalciuria (416 mg in a 24-hour collection), and normal PTH levels (5 pg/mL). Hematocrit and hemoglobin values stood at 34% and 11.5 gr/dL, respectively. Renal ultrasound indicated normal-sized kidneys with the presence of a 4 mm stone on the upper calyceal group of the right kidney without urinary obstruction. Chest X-ray showed bilateral hilar adenopathy and reticulo-nodular pattern. A chest and abdominal CT-scan revealed the presence of diffuse mediastinal and abdominal lymphadenopathy less than 1 cm in size. Serum angiotensin converting enzyme was significantly raised (128IU/L). Serology for HIV, CMV, EBV, Toxoplasma, and autoimmune diseases as well as PPD was negative.As sarcoidosis rarely invades with symptomatic hypercalcaemia [2] and renal involvement, [3] a diagnostic dilemma concerning lymphoproliferative disorders emerged. Mediastinoscopy was performed, and the presence of non-caseating granulomas in the resected lymph nodes established the diagnosis of sarcoidosis. As expected, 1,25-dihydroxy vitamin D3 serum concentration was increased (202 nmol/Lt, r.r. 25-120 nmol/Lt), thus justifying hypercalcaemia. [4] Upon admission, the patient was treated with normal saline and diuretics IV (furosemide, 80 mg/daily) aiming to normalize serum calcium. Renal insufficiency was attributed to hypercalcaemia as it subsided gradually by the correction of calcium serum concentration. Therefore, although renal biopsy was not performed (due to the rapid improvement of the renal function), the direct renal insult by sarcoidosis seems unlike. Following the pathological diagnosis of sarcoidosis, the patient was started on corticosteroids (methylprednizolone at a daily dose of 2 mg/kg) and ketoconazole (600 mg/day), resulting in a significant reduction in 1,25-dihydroxy vitamin D3 concentration (85 nmol/Lt). Ketoconazole has been reported to inhibit 1B-hydroxylation of vitamin D by acting directly on 1B-hydroxylase, thus lowering 1,25-dihydroxy vitamin D3 production in pulmonary macrophages and sarcoid granulomas. [5] After six months on corticosteroids, the patient's renal ...
