Tubulointerstitial changes seems to be of decisive importance among factors influencing the prognosis of IgA nephropathy. In consequence of decreased protection ability of mucous membranes, in some cases masked urinary tract infections may stand in the background of the tubulointerstitial changes. In this study the connection between urinary tract infections, significant bacteriurias and the progression of IgA nephropathy was retrospectively investigated. The data and the progress of the disease of 19 IgA nephropathy patients with significant bacteriuria (microbiologically identified) were compared to 19 IgA nephropathy patients of similar age, sex and the time of follow-up without bacteriuria. During the follow-up (on the average 8.5 years), the renal function (values of serum creatinine) decreased significantly (p < 0.05) in both groups, but there was no significant difference between the two groups. Neither at start, nor at the end of the follow-up no significant difference was found in the two groups in the prevalence of proteinuria, haematuria, hypertension and between the values of serum parameters. On the basis of these data we assume, that with the help of frequent medical check up and adequate antibiotic treatment the unfavourable effects of urinary tract infections (chronic tubulointerstitial changes) can probably be fended off.

Nitric oxide (NO) is claimed to have a role in the pathogenesis of immune-mediated glomerulonephritis and in the regulation of blood pressure (BP). NO rapidly converts to NO2-/NO3- which is excreted in the urine. We determined the daily NO2-/NO3- excretion in 26 IgA nephropathy (NP) patients and 20 healthy controls, recording the BP in each. There was no difference in NO2-/NO3- excretion between IgA NP patients and controls (999.1 +/- 66.8 vs. 1,051.2 +/- 53.0 mumol/day). The urinary excretion of NO2-/NO3- in IgA NP patients whose mean diastolic BP remained above 85 mm Hg in spite of antihypertensive therapy, was significantly decreased (n = 8; 734.38 +/- 87.83 mumol/day; p < 0.05). There was a significant inverse correlation between mean diastolic BP and urinary NO2-/NO3- (p < 0.006). NO2-/NO3- excretion decreased with aging (p < 0.01) in IgA NP patients, but not in controls. The fact that there was no difference between the urinary NO2-/NO3- excretion of IgA NP patients and controls argues against the idea that NO production in immune-mediated IgA NP can be increased. The decrease of urinary NO2-/NO3- in hypertensive and in older IgA NP patients may be correlated with the impaired NO production of the endothelium.