Renal histology in patients with elevated serum creatinine and concurrent normal urinalysis

INTRODUCTION Diagnosis of kidney disease is currently and primarily based on the measurement of serum creatinine, blood urea nitrogen, and urine output, and most kidney diseases with elevated serum creatinine accompany abnormal findings of urinalysis with microscopy, such as proteinuria or hematuria. The purpose of the current study was to determine the histologic diagnosis of patients with elevated serum creatinine and a concurrent normal urinalysis without underlying disease. METHODS The medical records of patients who had undergone kidney biopsies between January 1, 2003 and March 1, 2008 in three medical centers were retrospectively reviewed. The patients with an elevated serum creatinine level and a normal urinalysis were enrolled. The exclusion criteria were as follows: diabetes mellitus; hypertension; chronic liver disease; malignancies; autoimmune diseases; dependence on medications; hypokalemic nephropathy; age < 18 years. Age, duration of follow-up, post-biopsy management, and the change in levels of BUN and serum creatinine from pre-biopsy to the last visit were analyzed. RESULTS All 15 patients were included. The most frequent single diagnosis was acute interstitial interstitial nephritis, followed by hypertensive nephrosclerosis. Chronic interstitial nephritis, mesangial proliferative glomerulonephritis, acute tubular necrosis, secondary amyoloidosis, focal segmental glomerulosclerosis, and minor glomerular change were listed. The young group (< 40 years of age) included more patients with acute interstitial nephritis, and the old group (≥ 40 years of age) included more patients with hypertensive nephrosclerosis. CONCLUSION Based on a correct histological diagnosis, all of the patients, except one, were properly managed and had preserved kidney function until the last visit.