Sarcoidosis and Acute Kidney Injury

Abstract

Sarcoidosis is a multi-organ disease characterized by the formation of non-caseating epithelioid granulomas in many organs. The kidneys are not commonly affected but when the disease involves these organs. It is comprised of non-caseating granulomatous interstitial nephritis (GIN) and hypercalcemia-related disorders. In the latter case, acute kidney injury as initial presentation of the disease is a rare entity, and it is postulated to appear due to several pathogenic processes: (1) interstitial nephritis with or without granulomas, (2) nephrocalcinosis with or without nephrolithiasis, and (3) urethral obstruction. A 71-year-old man presented to the clinic with a history of lethargy, nausea, short memory loss and a 10 kg weight loss all of which appeared within the past 6 months. He was also known with prostate adenoma and was under the care of a urologist. Upon physical examination the following aspects were noted: blood pressure of 160/100 mmHg, heart rate 60 bpm and an irregular enlarged prostate. The chest X-ray was normal and blood samples revealed anemia, hypercalcemia, and increased values of urea and creatinine. An ultrasound of the kidneys was performed and no abnormalities were noted. The urinalysis showed the presence of protein +, glucose+, blood 2+, a few white cells and some granular casts. The next step was to perform a renal biopsy that revealed areas of lymphocytic tubulitis, mild mononuclear interstitial infiltrate, some non-necrotizing epithelioid granulomas comprised of Langerhans-type giant cells and epithelioid macrophages. Peri-tubular interstitial calcifications were also noted. As a result a histological diagnosis was summarized as acute or chronic granulomatous interstitial nephritis with nephrocalcinosis. A CT scan pf the chest was subsequently performed and it revealed calcified lymph nodes in the mediastinum involving the space between the aorta and the trachea and numerous nodules scattered bilateralally over the entire lung parenchyma with no apparent periseptal or perivascular association. These findings were diagnosed as sarcoidosis. The serum ACE level was found abnormal and therefore, a clinical diagnosis of sarcoidosis was made and the patient was started on 40 mg of oral prednisone daily with rapid improvement in the overall general condition. Sarcoidosis is an uncommon disease that should be suspected in front of a patient that presents with hypercalcemia and acute kidney injury. After excluding other causes of hypercalcemia such as multiple myeloma, primary hyperparathyroidism, and paraneoplastic phenomena, a renal biopsy is then indicated to confirm the diagnosis of sarcoidosis.