Effects of oral pyridoxine upon plasma and 24-hour urinary oxalate levels in normal subjects and stone formers with idiopathic hypercalciuria

1990 ◽  
Vol 18 (6) ◽  
pp. 393-396 ◽  
Author(s):  
P. Edwards ◽  
S. Nemat ◽  
G. A. Rose
Keyword(s):  
Normal Subjects ◽  
Idiopathic Hypercalciuria ◽  
Urinary Oxalate ◽  
Stone Formers

scholarly journals Sex differences in proximal and distal nephron function contribute to the mechanism of idiopathic hypercalcuria in calcium stone formers

2015 ◽  
Vol 309 (1) ◽  
pp. R85-R92 ◽  
Author(s):  
Benjamin Ko ◽  
Kristin Bergsland ◽  
Daniel L. Gillen ◽  
Andrew P. Evan ◽  
Daniel L. Clark ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Distal Tubule ◽  
Normal Subjects ◽  
Idiopathic Hypercalciuria ◽  
Distal Nephron ◽  
Stone Formers ◽  
Calcium Reabsorption ◽  
Normal Women ◽  
Normal Males ◽  
Normal Men

Idiopathic hypercalciuria (IH) is a common familial trait among patients with calcium nephrolithiasis. Previously, we have demonstrated that hypercalciuria is primarily due to reduced renal proximal and distal tubule calcium reabsorption. Here, using measurements of the clearances of sodium, calcium, and endogenous lithium taken from the General Clinical Research Center, we test the hypothesis that patterns of segmental nephron tubule calcium reabsorption differ between the sexes in IH and normal subjects. When the sexes are compared, we reconfirm the reduced proximal and distal calcium reabsorption. In IH women, distal nephron calcium reabsorption is decreased compared to normal women. In IH men, proximal tubule calcium reabsorption falls significantly, with a more modest reduction in distal calcium reabsorption compared to normal men. Additionally, we demonstrate that male IH patients have lower systolic blood pressures than normal males. We conclude that women and men differ in the way they produce the hypercalciuria of IH, with females reducing distal reabsorption and males primarily reducing proximal tubule function.

Evidence that postprandial reduction of renal calcium reabsorption mediates hypercalciuria of patients with calcium nephrolithiasis

2007 ◽  
Vol 292 (1) ◽  
pp. F66-F75 ◽  
Author(s):  
Elaine M. Worcester ◽  
Daniel L. Gillen ◽  
Andrew P. Evan ◽  
Joan H. Parks ◽  
Katrina Wright ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Serum Magnesium ◽  
Normal Subjects ◽  
Urinary Calcium ◽  
Idiopathic Hypercalciuria ◽  
Calcium Excretion ◽  
Stone Formers ◽  
Calcium Reabsorption ◽  
Renal Tubular ◽  
Filtered Load

Idiopathic hypercalciuria (IH) is common among calcium stone formers (IHSF). The increased urinary calcium arises from increased intestinal absorption of calcium, but it is unclear whether increased filtered load or decreased renal tubular reabsorption of calcium is the main mechanism for the increased renal excretion. To explore this question, 10 IHSF and 7 normal subjects (N) were studied for 1 day. Urine and blood samples were collected at 30- to 60-min intervals while subjects were fasting and after they ate three meals providing known amounts of calcium, phosphorus, sodium, protein, and calories. Fasting and fed, ultrafiltrable calcium levels, and filtered load of calcium did not differ between N and IHSF. Urine calcium rose with meals, and fractional reabsorption fell in all subjects, but the change was significantly higher in IHSF. The changes in calcium excretion were independent of sodium excretion. Serum parathyroid hormone levels did not differ between N and IHSF, and they could not account for the greater fall in calcium reabsorption in IHSF. Serum magnesium and phosphorus levels in IHSF were below N throughout the day, and tubule phosphate reabsorption was lower in IHSF than N after meals. The primary mechanism by which kidneys ferry absorbed calcium into the urine after meals is via reduced tubule calcium reabsorption, and IHSF differ from N in the magnitude of the response. Parathyroid hormone is not likely to be a sufficient explanation for this difference.

scholarly journals Evidence for net renal tubule oxalate secretion in patients with calcium kidney stones

2011 ◽  
Vol 300 (2) ◽  
pp. F311-F318 ◽  
Author(s):  
Kristin J. Bergsland ◽  
Anna L. Zisman ◽  
John R. Asplin ◽  
Elaine M. Worcester ◽  
Fredric L. Coe
Keyword(s):  
Fractional Excretion ◽  
Normal Subjects ◽  
Tubular Secretion ◽  
Idiopathic Hypercalciuria ◽  
Renal Handling ◽  
Stone Formers ◽  
Oxalate Secretion ◽  
Calcium Phosphorus ◽  
Urine Oxalate ◽  
Urinary Oxalate Excretion

Little is known about the renal handling of oxalate in patients with idiopathic hypercalciuria (IH). To explore the role of tubular oxalate handling in IH and to evaluate whether differences exist between IH and normal controls, we studied 19 IH subjects, 8 normal subjects, and 2 bariatric stone formers (BSF) during a 1-day General Clinical Research Center protocol utilizing a low-oxalate diet. Urine and blood samples were collected at 30- to 60-min intervals while subjects were fasting and after they ate three meals providing known amounts of calcium, phosphorus, sodium, protein, oxalate, and calories. Plasma oxalate concentrations and oxalate-filtered loads were similar between patients (includes IH and BSF) and controls in both the fasting and fed states. Urinary oxalate excretion was significantly higher in patients vs. controls regardless of feeding state. Fractional excretion of oxalate (FEOx) was >1, suggesting tubular secretion of oxalate, in 6 of 19 IH and both BSF, compared with none of the controls ( P < 0.00001). Adjusted for water extraction along the nephron, urine oxalate rose more rapidly among patients than normal subjects with increases in plasma oxalate. Our findings identify tubular secretion of oxalate as a key mediator of hyperoxaluria in calcium stone formers, potentially as a means of maintaining plasma oxalate in a tight range.

scholarly journals The Variability and Dietary Dependence of Urinary Oxalate Excretion in Recurrent Calcium Stone Formers

1987 ◽  
Vol 24 (4) ◽  
pp. 385-390 ◽  
Author(s):  
J M Brown ◽  
G Stratmann ◽  
D M Cowley ◽  
B M Mottram ◽  
A H Chalmers
Keyword(s):  
Calcium Intake ◽  
Normal Subjects ◽  
Urinary Calcium ◽  
Stone Disease ◽  
Calcium Excretion ◽  
Urinary Oxalate ◽  
Calcium Stone ◽  
Oxalate Excretion ◽  
Stone Formers ◽  
Urinary Oxalate Excretion

Twenty-two recurrent calcium stone formers had 24-h urinary oxalate excretions on their home diets which were significantly greater than those of 30 normal subjects (0·48±0·23 mmol/d; mean±SD compared with 0·31±0·11; P<0·01). The stone formers also demonstrated marked day to day variability in oxalate excretion indicating that a single normal urinary oxalate measurement did not exclude significant hyperoxaluria at other times. On a hospital diet containing 1000 mg calcium per day, urinary oxalate excretion fell significantly from 0·48±0·23 mmol/d to 0·32±0·12; P<0·01. As the urinary calcium excretion in and out of hospital was similar, it seems unlikely that low calcium intake at home was responsible for the hyperoxaluria. All patients had recurrent symptomatic stone disease and had been advised to avoid foods rich in oxalate. Whilst poor compliance is a possible explanation for the variability in oxalate excretion, we believe it is more likely that there is an inadvertent intake of oxalogenic precursors in their diet. As normal subjects do not demonstrate hyperoxaluria on similar home diets, stone formers may have a metabolic defect in the handling of these precursors.

Study of Circadian Rhythmicity of Urinary Excretion of Glycosaminoglycans in Normal Subjects and Stone Formers

Urolithiasis ◽  
1989 ◽  
pp. 243-243
Author(s):  
H. Sidhu ◽  
S. Vaidyanathan ◽  
A. K. Hemal ◽  
S. K. Thind ◽  
R. Nath ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Normal Subjects ◽  
Circadian Rhythmicity ◽  
Stone Formers
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