Changes in Zinc Metabolism During the Course of the Nephrotic Syndrome

Abstract

\s=b\The plasma zinc concentration and quantitative urinary zinc excretion were studied in 105 pediatric patients with the nephrotic syndrome or nephritis-nephrosis. The plasma level was decreased to a mean value of 51.7 \g=m\g/dLin patients with the nephrotic syndrome (controls, 85 \ g=m\ g/ dL). The rate of urinary zinc excretion was not different from that of the controls, with the exception of patients whose disease was in the polyuric phase of beginning remission where it was fivefold higher and those who had achieved a long-lasting remission of the disease. Since about two thirds of the plasma zinc is bound to albumin, an unchanged zinc-albumin ratio would reflect an equal zinc and albumin loss. The ratio, however, was increased twofold and thus does not adequately explain the hypozincemia. The low hair level of 86 \g=m\g/g may suggest a more profoundly disturbed zinc metabolism than originally thought.(Am J Dis Child 134: [46][47][48][49][50] 1980) Our interest in studying the plasma concentration and excretory rate of zinc in patients with nephrotic syndrome was stimulated by two observations. In 1942, McCance and Widdowson1 described two patients with albuminuria that was accompa¬ nied by a substantially increased zinc excretory rate. In contrast, Fairhall and HoyU had found earlier an essen¬ tially unchanged rate of zinc excretion in nephritis or nephrosis. In 1972, when studying the aminonucleoside nephrosis of rats, Freeman et al·1 observed an increase in the rate of zinc excretion almost parallel to the increase in the rate of protein excre¬ tion. At the same time, the plasma zinc levels decreased below normal. The second observation refers to stud¬ ies of Flynn et al· who reported a precipitous decrease in serum zinc concentration during corticosteroid treatment and who suspected a rela¬ tion to the adrenocorticotropic hor¬ mone production or corticosteroid se¬ cretion.We decided, therefore, to study changes in the metabolism of zinc in patients with the nephrotic syndrome, a disease that by definition is accom¬ panied by substantial proteinuria. In addition, most pediatrie patients with the nephrotic syndrome receive pro¬ longed corticosteroid treatment. Our results show that the plasma zinc level is decreased in patients with the ne¬ phrotic syndrome as long as proteinu¬ ria is present. The rate of urinary zinc excretion, however, is not increased and shows little change during the course of the nephrotic syndrome. SUBJECTS AND METHODSA total of 105 pediatrie patients who fulfilled the criteria for the nephrotic syndrome (anasarca, proteinuria, hypoalbuminuria, hypercholesterolemia), or glomerulonephritis and nephrotic syndrome (proteinuria, persistent hematuria, tran¬ sient or constant mild hypertension) were included in this study. They were sepa¬ rated into two groups, 81 patients with idiopathic nephrotic syndrome and 24 patients with a combination of nephritisnephrosis. Studies were also performed in seven patients with glomerulonephritis, but because of the small number, the data were no...

Trace Elements in Children Suffering from Idiopathic Nephrotic Syndrome

“…We found that plasma selenium levels were low in NS patients during both active and remission phase and plasma selenium level had a tendency to return to normal in remission, this is in good agreement with the results of selenium published by Mishra et al [9]. Additionally, we found that plasma zinc level was lower in the NS group in active and remission phase, which is in good agreement with the results published by Reimold [16] and Perrone et al [7], but not with those of Mishra et al [9], who observed no difference between NS and control groups in terms of plasma zinc level. Furthermore, in an experimental study, low serum v and high urinary zinc excretion were observed in nephrotic rats [17].…”

Copper and Zinc Metabolism in Aminonucleoside-Induced Nephrotic Syndrome

“…In this work, the levels of Zn decreased slightly in the spleen and lungs (81 and 87% of the control values, respectively) and were normal in 5 other tissues, therefore, these rats are not typically Zn deficient as those produced by ingestion of a Zn-deficient diet [23]. In con trast, in humans with NS, low Zn levels in hair [2,4], erythrocytes [4] and leukocytes [4] have been observed. The mechanism(s) involved in the metabolic alterations of Cu and Zn in PAN-nephrotic rats remain(s) unknown.…”

“…Patients with nephrotic syndrome (NS) have low serum levels of zinc (Zn) [1][2][3][4][5][6]. In addition, low levels of Zn in leukocytes [4], hair [2,4] and erythrocytes [4] have also been found in these patients.…”

“…In addition, low levels of Zn in leukocytes [4], hair [2,4] and erythrocytes [4] have also been found in these patients. The cause of Zn deficiency in human NS is not clearly understood.…”

“…It has been suggested that hypozincemia may be due to increased urinary excre tion of Zn [3,4,6]. However, some investigators have not observed enhanced urinary excretion of Zn in these patients [1,2,5,7], On the other hand, patients with NS have increased urinary excretion of copper (Cu) [6,[8][9][10], However, serum Accepted : February 26. 1993 Cu deficiency has been demonstrated in some [8][9][10] but not in all studies [6,10,11].…”