Volume homeostasis in schistosomal patients with and without renal involvement

ABSTRACT

The aim of this study was studying some humoral and renal mechanisms controlling volume homeostasis during volume expansion and volume depletion among schistosomal patients with and without renal involvement. The subjects included in this study were ten non ascitic schistosomal patients [group A], another ten non ascitic proteinuric schistosomal patients [group B], ten control subjects [group C]. All groups were subjected to full history taking, clinical examination and investigations [stool analysis or rectal snip biopsy, urine analysis and urine protein estimation, renal function tests, liver function tests, hepatitis viral markers and percutaneous renal biopsy for nephrotic patients]. Experimental protocol included two studies study I this included infusion of isotonic saline [0.9%] in a dose of 40 ml/kg body weight over 30 minutes for acute volume expansion. Study 2 this included the administration of furosemide in a dose of 0.75 mg/kg body weight during one minute. The change in plasma volume after each study was calculated. Estimation of at rial natriuretic peptide [ANP] by radioimmunoassay basally and 1 hour after the study, plasma renin activity [PRA] and plasma aldosterone [PA] were done pre-study as well as, 1,2, and 3 hours post study. Fractional excretion of sodium, urinary sodium excretion rate, free water clearance as well as urinary flow rate were calculated before and after the study. Serum proteins and serum albumin were significantly lower in the schistosomal proteinuric group [group B]. Prothrombin activity showed a significant decrease in both groups A and B. All subjects of the three groups were negative for the studied viral markers. All nephrotic patients [group B] were biopsied and revealed membrano-proliferative type of glomerulonephritis. The percentage increase and decrease in plasma volume after volume expansion and depletion were comparable in the three studied groups with no significant difference. The basal ANP showed no significant difference between the three groups, it showed a significant rise especially in group B after volume expansion and a significant decline after volume depletion in the three groups. Schistosomal proteinuric patients [group B] showed incomplete suppression of PRA after volume expansion, there was a sustained rise in PRA and PA in schistosomal patients [group A] after volume depletion. The basal PA was significantly higher in schistosomal patients [group A] than the controls, it showed a significant decrease after volume expansion in the three studied groups. Fractional excretion of sodium showed a significant rise after volume expansion in the three studied groups, there was a significantly lower value in the first hour interval in all schistosomal patients [group A and B] than that of the control group[C], after volume depletion it showed a significant rise in the first and second hours only in all schistosomal patients [A and B]. Urinary sodium excretion rate showed a significant increase after volume expansion in the three studied groups, but the natriuresis was found to be impaired after the first hour in all schistosomal patients [group A and B] in comparison to the control subjects [group C]. After volume depletion,urinary sodium excretion rate showed a significant increase in the three studied groups. All schistosomal patients [group A and B] showed blunted natriuretic and diuretic response to furosemide when compared to the control group [C]. Free water clearance after volume expansion showed a significant rise in the first hour interval in group A, in the first and second hour interval in B and in the three hours intervals in C. After volume depletion there was no significant difference in the basal, first,second, and third hour interval values between the three groups. Urine flow rate increased significantly after volume expansion and diuretics in the three groups. All schistosomal patients [group A and B] showed significant lower values in the first and second hour after both volume expansion and depletion than the controls. ANP was involved in the regulation of blood volume in schistosomal patients with and without proteinuria. The high basal aldosterone levels in schistosomal patients may be related to impaired metabolic degradation rather than increased production. There was blunted natriuresis and diuresis in schistosomal patients early in the preascitic stage, this may be due to resistance to the properly released ANP. This resistance was related neither to its hypotensive action nor to hyperaldosteronism.The impaired urinary sodium excretion may be related to the increased tubular reabsorption. Schistosomal proteinuric patients tended also to retain sodium inspite of the proper hormonal response, so renal resistance may be a cause. Schistosomal patients tended to retain water and the ability to excrete free water was better in schistosomal proteinuric There was a state of diuretic resistance to furosemide in schistosomal patients with and without proteinuria