Proteinuria and plasma hexosugars in early-stage glomerulonephritis.

Marked changes in the plasma concentration of several non-glucose monosaccharides have been detected among patients++ with end-stage renal disease. To find changes specific to renal disease and not caused by a failing urinary excretion, we studied the plasma monosaccharide concentration in patients with early-stage glomerulonephritis whose renal function was normal or only mildly compromised. Plasma mannose, fructose and 1,5-anhydroglucitol (1,5-AG) concentrations were measured using gas chromatography/mass spectrometry and isotope-labelled sugar standard additions. The daily urinary protein excretion was positively correlated with the plasma cholesterol (r = 0.785), mannose (r = 0.550), triglyceride (r = 0.531 ) and fructose (r = 0.401) concentrations, while the correlation with 1,5-AG (r = -0.581) was inverse. The correlations were statistically significant. As previous studies have revealed a close positive correlation between the plasma mannose and glucose concentrations, we calculated the mannose/glucose concentration ratio to find out whether the increase in mannose concentration was or was not explained by ambient glucose. There was a strong correlation between the ratio and the urinary protein excretion (r = 0.704). It is inferred that the metabolic syndrome associated with glomerulonephritis and characterised by hyperlipidemia also involves a derangement in mannose and 1,5-AG metabolism.