Glomerular filtration rate and tubular involvement during acute disease and convalescence in patients with nephropathia epidemica.

Glomerular filtration rate (GFR) and tubular involvement were studied in 74 patients with serologically verified nephropathia epidemica (NE). Increased levels of serum creatinine and serum beta 2-microglobulin were documented in 96% and 99% of the patients, respectively. The mean of the lowest estimated GFR was 26 ml/min. Proximal tubular reabsorptive capacity was assessed by urinary loss of beta 2-microglobulin and cell damage by urinary activity of N-acetyl-beta-D-glucosaminidase. Both of these parameters were elevated in most of the patients during the acute phase of the disease. Increased serum levels of Tamm-Horsfall-specific IgG and/or IgA occurred in 72 of 74 patients. No patient required dialysis and there was no mortality. Six months after discharge only three patients had a GFR less than 80 ml/min as estimated by [51Cr]EDTA clearance; two of these had underlying chronic diseases and one had suffered clinically severe NE. Desmopressin tests showed decreased urine osmolarity in three patients 8 months after discharge. These three had chronic diseases, which may have contributed to the impaired tubular function. Thus, there was a markedly decreased GFR and a tubular dysfunction in the acute phase of NE. Most patients recovered within a few months and none showed evidence of chronically impaired renal function due to NE.