Assessment of Hypervolemia by Cyclic 3’5’-Guanosine Monophosphate in Pediatric Patients on Hemodialysis

Accessible online at: http://BioMedNet.com/karger Dear Sir, The exact determination of the hydration state represents one of the central problems of maintenance hemodialysis therapy [1]. Usually, clinical signs, radiological features on chest X-ray and echocardiography are used for the determination of dry body weight. However, these criteria are relatively insensitive and, as a consequence, a considerable number of hemodialysis patients remain overhydrated. In children with endstage renal disease assessment of dry body weight is particularly difficult. Weight gain may be interpreted as growth although it might be caused by sodium and water retention. Extracellular fluid volume overload is the major stimulus for secretion of atrial natriuretic peptide (ANP) and its second messenger cyclic 3)5)-guanosine monophosphate (cGMP). In a number of studies we have shown that plasma cGMP levels are reliable markers for fluid overload in adults on renal replacement therapy with normal heart function [2–4]. In order to test the ability of cGMP as a possible biochemical marker for fluid overload in children, we designed a prospective longitudinal study. Preand postdialytic cGMP concentrations were measured over a period of 9 months (9 repeated measurements for each patient) in 15 children and adolescents (9 males, 6 females) with end-stage renal disease treated by intermittent hemodialysis (4 h three times per week). The age ranged between 8 and 19 years with a mean age of 15 B 3 years. The primary kidney diseases were dysplastic kidneys (5 patients), glomerulonephritis (3 patients), nephronophtisis (2 patients), amyloidosis (2 patients), Alport’s syndrome (1 patient), hyperoxaluria (1 patient) and polycystic kidney disease (1 patient). The ideal body dry weight was estimated in all patients at the beginning of the study by clinical means, echocardiography, vena cava diameter and chest X-ray. Fifteen healthy sexand age-matched children and adolescents served as controls. cGMP was determined in alcohol-extracted plasma by radioimmunoassay as has been described in detail previously [5]. Compared with healthy controls, the predialytic plasma concentrations of cGMP were markedly elevated in all 15 volumeexpanded hemodialyzed children (16.8 B 7.1 vs. 4.2 B 1.8 pmol/ml; p ! 0.05). Before hemodialysis, the mean body weight exceeded the estimated dry weight by 1.8 B 0.6 kg. The circulating cGMP values in these patients were influenced by their residual renal function: children with daily urinary excretion over 200 ml had significantly lower predialytic plasma cGMP levels than did those with anuria (13.3 B 5.6 vs. 23.4 B 4.3 pmol/ml; p ! 0.05). In contrast, postdialytic cGMP values were not influenced by urinary volume (6.6 B 2.3 vs. 6.2 B 2.7 pmol/ml). Removal of excess body fluid during hemodialysis resulted in a significant decrease in cGMP values (6.7 B 2.2 vs. 16.8 B 7.1 pmol/ml; p ! 0.05) (fig. 1A). However, postdialytic cGMP levels were still significantly higher than in normal controls (6.7 B 2.2 vs. 4.2 B 1.8 pmol/ml; p ! 0.05). None of our studied patients had on an average a postdialytic cGMP concentration over 10 pmol/ml during the 9-month follow-up. As shown in figure 1B, the reduction in body brought to you by CORE View metadata, citation and similar papers at core.ac. uk