Glomerular/tubular mixed-type proteinuria in a 3-year-old boy with mental retardation and hyperkinesis

A 3-year-old boy with mixed glomerular/tubular proteinuria, mental retardation, and hyperkinesis is described. The proteinuria was discovered at the age of 3 years on urinary mass screening. Most of the urinary protein consisted of albumin, accompanied by increases in low molecular weight proteins, including beta 2-microglobulin and alpha 1-microglobulin. Mixed glomerular/tubular proteinuria is known to be caused by the following conditions: chronic renal failure, chronic pyelonephritis, cadmium poisoning, tubulointerstitial nephritis of various etiologies, and after strenuous, short-term, exhaustive exercise. The present patient did not display any of these disorders or conditions.