Renal phosphate leak in patients with idiopathic hypercalciuria and calcium nephrolithiasis

Negri, Armando; Spivacow, Rodolfo; Valle, Elisa Del; Fradinger, Erich; Marino, A; Zanchetta, José R.

doi:10.1007/s00240-003-0353-y

Cited by 7 publications

(3 citation statements)

References 13 publications

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“…We found in 100 kidney stone formers with idiopathic hypercalciuria that only 9 % had excess urine phosphate loss [59]. In the present series of 3040 patients, those with high urine phosphate excretion was 7.76 %, most of them associated with idiopathic hypercalciuria 69.9 %.…”

Section: Discussionmentioning

confidence: 71%

Biochemical diagnosis in 3040 kidney stone formers in Argentina

et al. 2015

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Nephrolithiasis is a frequent condition in urology that has an important recurrence and high impact in health economy. Knowing the biochemical abnormalities implicated in its pathogenesis is mandatory to establish therapeutic aims. Our objectives are to present the results in 3040 kidney stone formers in Argentina. All patients were selected after completing an ambulatory metabolic protocol with diagnostic purposes. There were 1717 men, (56.48%), with a mean age of 45±12 years, and 1323 women, (43.52%), mean age 44±12 years. 2781 patients had biochemical abnormalities, (91.49%), and were arbitrarily divided in two groups: those who had only one (single) biochemical abnormality (n=2156) and those who had associated abnormalities (n=625). No biochemical abnormalities were found in 259 patients (8.51%). The abnormalities present, single and associated, in order of frequency, were idiopathic hypercalciuria, (56.88%), hyperuricosuria (21.08%), unduly acidic urine (10.95%), hypocitraturia (10.55%), hypomagnesuria (7.9%), primary hyperparathyroidism (3.01%), hyperoxaluria (2.6%), and cystinuria (0.32%). We performed in 484 patient's stone composition and found calcium oxalate stones related to idiopathic hypercalciuria predominantly while uric acid stones to unduly acidic urine. In conclusion, the biochemical abnormalities described are similar to those found in a previous series of our own and to those reported in the literature. Its diagnosis is important to therapeutic purposes to avoid eventual recurrence.

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Section: Discussionmentioning

confidence: 71%

Biochemical diagnosis in 3040 kidney stone formers in Argentina

et al. 2015

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“…22 However, renal phosphate excretion does not seem to correlate with urine calcium excretion. 23 In contrast to simple Mendelian disorders, the identification of genes causing complex traits such as idiopathic hypercalciuria represents a formidable challenge. Performing candidate gene studies in subgroups of patients with particular phenotypes such as mild phosphate wasting is a more targeted approach with a higher potential yield for gene discovery.…”

Section: Discussionmentioning

confidence: 99%

NPT2a gene variation in calcium nephrolithiasis with renal phosphate leak

Lapointe

Tessier

Paquette

et al. 2006

Kidney International

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A decrease in renal phosphate reabsorption with mild hypophosphatemia (phosphate leak) is found in some hypercalciuric stone-formers. The NPT2a gene encodes a sodium-phosphate cotransporter, located in the proximal tubule, responsible for reclaiming most of the filtered phosphate load in a rate-limiting manner. To determine whether genetic variation of the NPT2a gene is associated with phosphate leak and hypercalciuria in a cohort of 98 pedigrees with multiple hypercalciuric stone-formers, we sequenced the entire cDNA coding region of 28 probands, whose tubular reabsorption of phosphate normalized for the glomerular filtration rate (TmP/GFR) was 0.7 mmol/l or lower. We performed genotype/phenotype correlations for each genetic variant in the entire cohort and expressed NPT2a variant RNAs in Xenopus laevis oocytes to test for cotransporter functionality. We identified several variants in the coding region including an in-frame 21 bp deletion truncating the N-terminal cytoplasmic tail of the protein (91del7), as well as other single-nucleotide polymorphisms that were non-synonymous (A133V and H568Y) or synonymous. Levels of TmP/GFR and urine calcium excretion were similar in heterozygote carriers of NPT2a variants compared to the wild-type (wt) homozygotes. The transport activity of the H568Y mutants was identical to the wt, whereas the N-terminal-truncated version and the 91del7 and A133V mutants presented minor kinetic changes and a reduction in the expression level. Although genetic variants of NPT2a are not rare, they do not seem to be associated with clinically significant renal phosphate or calcium handling anomalies in a large cohort of hypercalciuric stone-forming pedigrees.

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“…Several studies of phosphate excretion have shown that patients with idiopathic hypercalciuria have hyperphosphaturia or renal phosphate leak. However, the frequency of renal phosphate leak in these patients remains unclear [22][23][24][25].…”

Section: Discussionmentioning

confidence: 99%

Association between the metabolic profile of urolithiasis in children with idiopathic hypercalciuria and the composition of the stone assessed by infrared spectroscopy

Placzyńska,

Milart,

Lubas

et al. 2023

polp

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Introduction: Urolithiasis is an increasingly common condition. Each patient after stone passage should have stone analysis performed. Every child with a urinary stone should be given a complete metabolic evaluation, and the stone analysis is an essential component of it. The aim of the study was to establish the relation between the metabolic profile of urolithiasis in children with idiopathic hypercalciuria and the composition of the excreted stone. Material and methods:The study included 26 children with urolithiasis (aged 1-17 years) from whom stones were obtained for the analysis. The urine pH and the 24-hour urine excretion of calcium, phosphorus, magnesium and oxalate as well as spot urinalysis including ratio of crystalloids to creatinine from the second voided urine sample of the day were assessed. Urinary stones were analyzed by infrared spectroscopy. The relation between the metabolic data and the stone type was then analyzed, taking into account two types of minerals: stones with a predominance of calcium oxalate dihydrate (weddellite) and calcium oxalate monohydrate (whewellite). Results: No correlation was found between the individual serum metabolic parameters of the patient and the composition of excreted stones. Substantially lower urinary excretion of phosphates, oxalate, magnesium and lower urinary pH were found in the group with predominant weddellite stones. A reduced value of each of these 4 variables increased more than sixfold the chance of diagnosing urolithiasis with stone composed of over 60% weddellite. Conclusions:The urinary metabolic profile is associated with the composition of renal stones estimated in infrared spectroscopy in children with idiopathic hypercalciuria. The coexistence of several urinary excretion anomalies improves the prediction of the composition of the stones.

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Renal phosphate leak in patients with idiopathic hypercalciuria and calcium nephrolithiasis

Cited by 7 publications

References 13 publications

Biochemical diagnosis in 3040 kidney stone formers in Argentina

Biochemical diagnosis in 3040 kidney stone formers in Argentina

NPT2a gene variation in calcium nephrolithiasis with renal phosphate leak

Association between the metabolic profile of urolithiasis in children with idiopathic hypercalciuria and the composition of the stone assessed by infrared spectroscopy

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