Divalent Ion Excretion in Chronic Kidney Disease: Relation to Degree of Renal Insufficiency

Abstract

1.The excretory patterns of sodium, calcium, magnesium and phosphorus were evaluated in seventy-eight patients with varying degrees of renal insufficiency, and in twelve normal subjects.2. In mild renal failure the fractional excretion of filtered sodium, magnesium and phosphorus are significantly higher while that of calcium is significantly lower than values seen in normals. In advanced renal failure the fractional excretions of the filtered loads of all these ions increase steeply. These patterns are not influenced by the type of renal disease.3. The fractional excretions of filtered sodium and calcium, calcium and magnesium, and sodium and magnesium were plotted against each other. The analysis of the plots showed that the fractional excretions of their filtered loads correlate poorly in patients with mild and moderate renal insufficiency, but closely in patients with severe renal failure. 4.These results indicate that the relation between the renal handling of divalent ions is not uniform at all levels of renal insuEciency. The dissociation between the excretory patterns observed in patients with early renal failure is consistent with the concept that different mechanisms may influence each individual ion separately. This is in contrast to the close association which exists between the excretory patterns of these ions in patients with advanced renal disease, and in which a single common mechanism may underlie the renal handling of these ions.The fractional renal tubular reabsorption of filtered divalent ions is depressed in chronic kidney disease (Goldman & Bassett, 1954; Better et al., 1967; Steele et al., 1968). The mechanism@) underlying this phenomenon is not well deiined. In a recent study a close relationship between the renal excretion of sodium, calcium and magnesium was observed in patients with advanced renal failure and a common regulatory mechanism was proposed to explain the

Fibroblast Growth Factor-23 in Early Chronic Kidney Disease

“…Low calcitriol levels also compromise intestinal calcium absorption, especially when dietary calcium intake is low (35)(36)(37). Low calcitriol levels may thus contribute to the hypocalciuria, observed in this study and in previous studies examining patients with mild-to-moderate renal insufficiency (2).…”

Renal handling of calcium and phosphorus in experimental renal hyperparathyroidism in dogs

“…The renal handling of phosphorus (P) in renal failure has been widely studied in humans and animals, but this is not the case for the renal handling of calcium (Ca). In humans, it has been observed that although the overall urinary excretion of calcium is generally reduced, the fractional excretion of calcium (FECa) increases in advanced renal failure [4] but it does not happen the same in moderate renal failure [22]. The findings reported in animals [2,20] have not been able to clarify this matter.…”

“…In humans, however, FECa and calciuria diminish with moderate renal failure [22]. This difference has been explained as a consequence of a better renal maintenance of calcitriol production by the remnant kidney in animals subjected to renal ablation.…”

Influence of renal function on clinico-pathological features of primary hyperparathyroidism

“…Hypocalciuria is the expected finding in normocalcemic patients with renal insufficiency, even when the GFR is minimally reduced. When the filtration rate falls to 25% or less, there is an increase in fractional calcium excretion that frequently parallels an increase in fractional sodium excretion (28). According to the NIH Consensus Development Conference statement (13), surgery is recommended if 24 h urinary calcium excretion is .…”