Tubular dysfunctions in the diagnostic differentiation of glomerulonephritis, pyelonephritis, and diabetic nephropathy.

Concentration and acidification capability was tested in 41 patients with chronic pyelonephritis (PN), 14 patients with chronic glomerulonephritis (GN), 16 patients with diabetic nephropathy (DNP) and 12 healthy controls. Significant differences appeared between PN and GN, PN and DNP comparing a quotient between percent of normal osmolarity and percent of normal creatinine clearance. Similar results were obtained using a quotient creatinine clearance/ammonia excretion, which enabled the differentiation of PN from the other groups. The tubular functions of concentration and ammonia excretion in relation to creatinine are clinically useful in the differentiation of pyelonephritis from glomerular kidney diseases.