El cociente calcio/creatinina de ayunas en pacientes con litiasis cálcica y su relación con la hipercalciuria y el metabolismo fosfocálcico / The fasting calcium/ creatinine ratio in patients with calcium stones and the relation with hypercalciuria and phosphocalcium metabolism

OBJETIVO: Determinar la importancia del cociente calcio/creatinina de ayunas en pacientes con litiasis cálcica y su relación con la hipercalciuria y metabolismo fosfocálcico. MÉTODOS: Estudio transversal que incluye 143 pacientes divididos en dos grupos según calcio/creatinina en ayunas. Grupo 1:66 pacientes (calcio/creatinina<0,11); Grupo 2:77 pacientes (calcio/creatinina>0,11). Se realiza estudio comparativo entre grupos de parámetros del metabolismo fosfo-cálcico y excreción de marcadores litogénicos en orina. Estudio de correlación lineal calciuria- calcio/creatinina en ayunas. Estudio estadístico con SPSS 17.0, considerando p≤0,05. RESULTADOS: Destaca en los pacientes del grupo 2 una excreción aumentada de calcio en orina de 24 h respecto grupo 1 (229,3 vs 158,1; p = 0,0001) y de calcio/citrato (0,47 vs 0,34; p = 0,001). Existe correlación lineal positiva y significativa entre niveles de calcio en orina de 24 h y cociente calcio/creatinina en ayunas (R=0,455; p = 0,0001) y se establece un punto de corte en 0,127 del cociente (sensibilidad 72% y especificidad 66%) para determinar hipercalciuria (excreción mayor 260 mg en 24 h). CONCLUSIONES: La elevación del calcio/creatinina en ayunas determina mayor excreción de calcio en 24 h, aunque la sensibilidad y especificidad para determinar hipercalciuria no es elevada

OBJECTIVE: To determine the importance of fasting calcium/creatinine ratio in patients with calcium stones and its relation with hypercalciuria and phospho-calcium metabolism. METHODS: Cross-sectional study including 143 patients divided into two groups according to fasting calcium/creatinine. Group 1: 66 patients (calcium/ creatinine0.11). A comparative study is performed between groups including phospho-calcium metabolism parameters and excretion of urinary lithogenic markers. Linear correlation studying calciuria and fasting calcium/ creatinine was performed. SPSS 17.0 statistical analysis software was used, considering p≤0.05. RESULTS: It is noteworthy that group 2 had increased 24 h urine calcium excretion in comparison to group 1 (229.3 vs 158.1; p = 0.0001) and calcium/citrate (0.47 vs 0.34; p = 0.001). There is a positive and significant correlation between calcium levels in 24 h urine and fasting calcium/creatinine (R=0.455; p = 0.0001) and a cutoff is set at 0.127 (sensitivity 72%, specificity 66%) to determine hypercalciuria (>260 mg in 24 h). CONCLUSIONS: Increased fasting calcium/creatinine determines increased 24 hours calcium excretion, although the sensitivity and specificity to determine hypercalciuria is not high

Urinary excretion of calcium, magnesium, phosphate, citrate, oxalate, and uric acid by healthy schoolchildren using a 12-h collection protocol.

BACKGROUND: Improving knowledge about normal urine composition in children is important for early prevention of lithiasis. We describe urinary excretion values of calcium (Ca), magnesium (Mg), phosphate (P), citrate (Cit), uric acid (Ur), and oxalate (Ox) in healthy children with and without a family history of lithiasis, using a 12-h urine collection protocol. METHODS: Urine samples were obtained from 184 children (5-12 years): a spot sample collected in the afternoon, and a 12-h overnight sample. Solute/creatinine (Cr) and 12-h solute excretion was calculated. RESULTS: Urinary excretion values of the studied solutes are presented as percentile values, separately for each type of sample. Due to age-related differences in the solute/creatinine ratios, except for Ca and Cit, results are described according to the child's age. The presence of excretion values related to an increased risk of lithiasis was more common in children with a family history. CONCLUSIONS: We report data from urine samples collected by using a simplified collection protocol. The observed differences between children with and without a family history of lithiasis could justify that in population studies aimed at setting reference values, the former are excluded.

Hippuric acid as a significant regulator of supersaturation in calcium oxalate lithiasis: the physiological evidence.

At present, the clinical significance of existing physicochemical and biological evidence and especially the results we have obtained from our previous in vitro experiments have been analyzed, and we have come to the conclusion that hippuric acid (C6H5CONHCH2COOH) is a very active solvent of Calcium Oxalate (CaOX) in physiological solutions. Two types of experiments have been discussed: clinical laboratory analysis on the urine excretion of hippuric acid (HA) in patients with CaOX lithiasis and detailed measurements of the kinetics of the dissolution of CaOX calculi in artificial urine, containing various concentrations of HA. It turns out that the most probable value of the HA concentration in the control group is approximately ten times higher than the corresponding value in the group of the stone-formers. Our in vitro analytical measurements demonstrate even a possibility to dissolve CaOX stones in human urine, in which increased concentration of HA have been established. A conclusion can be that drowning out HA is a significant regulator of CaOX supersaturation and thus a regulation of CaOX stone formation in human urine. Discussions have arisen to use increased concentration of HA in urine both as a solubilizator of CaOX stones in the urinary tract and on the purpose of a prolonged metaphylactic treatment.

Application of mineralogical techniques in the study of human lithiasis.

The authors review the mineralogical methods and techniques of analyzing calculi, stony concretions in the body. They discuss the main types of kidney stones (prostate, testicular, salivary, and bile) and the different diagnostic methods in mineralogy. By applying the techniques of optical microscopy and electron microscopy, they describe the different characteristics of human stones, based on extensive experience as evidenced by their numerous studies.

[Risk of lithiasis and urolithiasis in children with unspecific inflammatory bowel disease]. / Zagroienie kamica i kamica ukladu moczowego u dzieci z nieswoistymi zapaleniami jelit.

UNLABELLED: Urolithiasis is a disease of a complex, often systemic and not fully unequivocal, etiopathological mechanism, resulting in concrement crystallization The aim of study was the evaluation of frequency of occurrences of crystallization risk states and urolithiasis in children with IBD. MATERIAL AND METHODS: The study was conducted on 35 children aged between 12 and 18 with confirmed ulcerative colitis (25 children) and Crohn disease (10 children). In all children regiular urine examination and urine inoculation were conducted, as well as stimation of concrement crystallization risk index in a twenty-four hour urine collection. Urinary tract ultrasound as well as evaluation of erythrocytes in urine sediment in phase contrast microscope,have been performed. Control group consisted of 20 children without digestive tract complains. RESULTS: In 13 (37%) of examined children, urolithiasis occured in family history. The general urine examination revealed in 27 (77%) examined children existence of erytrocyturia of various degree and the evaluation in phase contrast microscope indicated their extraglomucal origin. The ion-creatininal analysis of twenty-four hour urine collection revealed in 29 (82.2%) children risk of oxalate-calcium concrements crystallization and in 6 (17%) children--of oxalate concrements crystallization. USG examination revealed in 4 (11.4%) children existence of single or multiple concrements in urinary system. Analysis of 1 twenty-four hour urine collection indicated the decrease of magnesium ions in 27 (77%) examined children. In control group only in 2 (5.7%) children the risk of occurrence of phosphate-ammonium concrements crystallization, which was significantly lower in examined group (p < 0.01). CONCLUSIONS: Unspecific intestine inflammations have an influence on the occurrence of crystallization risk states, as well as a fully symptomatic urolithiasis.

Cristalúria como um método auxiliar de investigação de pacientes litiásicos: uma experiência na Região Metropolitana de Fortaleza / Cristalluria like method of lithiasis investigation in patients: an experience in the metropolitan region of Fortaleza

Objetivo: identificar, através da cristalúria, os cristais mais freqüentemente observados em portadores de litíase urinária, na região de Fortaleza. Materiais e métodos: 755 cristalúrias proveniente de 464 pacientes, 51,3 porcento masculino, idade de 32,1 ± 1,2 anos, no período de 1993 a 1996. Resultados: A chance de cristalúria positiva nesta população variou de 34,6 porcento a 41,6 porcento. Nos pacientes litiásicos, a cristalúria mostrou uma sensibilidade de 40,7 porcento e especificidade de 63,9 porcento. Os cristais mais freqüentemente, em ordem decrescente: COD, COM, AUD, PACC, bruxita e estruvita. Conclusão: Nossos resultados sugerem que oxalato e ácido úrico podem desempenhar um importante papel na patogênese dos cálculos urinários nesta Região.

Studies of urinary cystine precipitation in vitro: ontogeny of cystine nephrolithiasis and identification of meso-2,3-dimercaptosuccinic acid as a potential therapy for cystinuria.

Children with fully recessive (Type I/I) cystinuria have a high risk of stone formation in the first decade of life. To assess the tendency for cystine to precipitate in individual urine samples, we developed an in vitro assay in which radiolabelled cystine (4mM) was dissolved in urine at 37 degrees C after alkalization to pH 10. Samples were then brought to pH 5, cooled, and centrifuged. The % decrease in supernatant cpm was used as a measure of cystine precipitation (CP). CP varied widely among normal children (74%+/-34) whereas variability of repeated determinations on a single adult individual was modest (64%+/-3.3). The assay was used to compare various potential therapies for cystinuria. Precipitation of exogenous cystine from normal urine was strongly inhibited by addition of D-penicillamine (CP: 8%+/-3) or dimercaptosuccinic acid (DMSA) (CP: 5%+/-1), at urinary concentrations attained by standard oral doses of each drug. Mercaptopropionylglycine (MPG) was moderately effective (CP: 43%+/-9), whereas captopril was a weak inhibitor (CP: 63%+/-12). Precipitation of endogenous cystine (2191 micromol/L) from a cystinuric patient showed that DMSA and D-penicillamine were again highly effective compared to the other agents. In addition DMSA and penicillamine added to the same patient's urine reduced the free cystine by 50% (as measured by automated amino acid analyzer) whereas MPG and captopril had no effect. In conclusion, DMSA is comparable to D-penicillamine as an in vitro inhibitor.

Hyperoxaluric calcium nephrolithiasis.

Hyperoxaluria leads to increased calcium oxalate supersaturation and calcium oxalate stone formation. Excess oxalate can arise from endogenous overproduction as in primary hyperoxaluria or from dietary sources. In the last 15 years great strides have been made in the diagnosis and treatment of primary hyperoxaluria. However options still seem limited in treating the mild hyperoxaluria found in many stone formers. Inadequate knowledge of food oxalate content, the effect of dietary oxalate precursors on oxalate excretion, and the factors affecting handling of oxalate by the intestine prevent development of rational therapies for treatment of hyperoxaluria. Recent studies of oxalate degrading bacteria and renewed interest in the role of diet calcium in oxalate absorption may lead to better therapeutic strategies for hyperoxaluric calcium nephrolithiasis.

Citrato urinário na nefrolitíase / Urinary citrate in nephrolithiasis

O citrato tem dois efeitos importantes na prevençäo da nefrolitíase conhecidos como efeitos solubilizante e inibidor da cristalizaçäo dos sais de cálcio. É um ácido tricarboxílico que faz parte do ciclo de Krebs, sendo livremente filtrado e excretado pelos rins. A sua excreçäo pela urina pode sofrer influência de vários fatores, tais como a idade, o sexo, o conteúdo de ácido cítrico, proteínas e sódio na dieta, a atividade física, o equilíbrio ácido-básico, etc. Este trabalho tem como objetivo verificar a influência do sexo e da idade na excreçäo de citrato pela urina em pacientes com nefrolitíase. Para tal, realizamos a medida de citrato na urina de 24 horas (método enzimático) em 98 indivíduos do sexo masculino (36 ñ 13,5 anos) e 124 do sexo feminino (36 ñ 12,7 anos), todos com cálculo renal. Verificamos que o sexo influenciou significativamente na excreçäo urinária de citrato, com as mulheres excretando mais (527 ñ 225 mg/24 horas) do que os homens (409 ñ 210 mg/24 horas) (p=0,0001). A prevalência de hipocitratúria foi bem maior nos homens (41 porcento) do que nas mulheres (18 porcento). Quando os dois grupos (sexo masculino e feminino) foram separados de acordo com a idade observamos que, até os 40 anos, as mulheres excretaram mais citrato do que os homens. Se considerarmos somente o fator idade verificamos que homens até 20 anos apresentaram valores de citrato significativamente menores do que aqueles com idade acima de 20. Já nas mulheres, a excreçäo de citrato pela urina näo foi estatisticamente diferente nas categorias de idade estudadas

Avaliaçäo de pacientes com litíase renal em regiäo de clima quente / Assessment of kidney stone patients in hot regions

O objetivo deste estudo é desenvolver um serviço de litíase renal e detectar as alteraçöes metabólicas associadas a essa doença em pacientes da cidade de Catanduva, Säo Paulo. Foram estudados 65 pacientes (40 mulheres e 25 homens), entre 1996 e 1999, com idade variando entre 18 e 67 anos. O protocolo utilizado consistiu de avaliaçäo clínica e exames complementares (bioquímica de imagem e dos principais elementos litogênicos plasmáticos e urinários). Para a análise dos resultados, foi utilizado o teste "t" de Student para amostras independentes e consideradas insignificantes quando p é menor que 0,05. Pelo menos, uma alteraçäo metabólica foi encontrada em 98,5 porcento dos casos avaliados.A reduçäo do volume urinário (77 porcento) foi a alteraçäo metabólica mais frequente, seguida pela hipocitratúria (62 porcento), hiperexcreçäo de ácido úrico (32 porcento), hipercalciúria (27 porcento), outras alteraçöes (8 porcento),e sem alteraçäo detectada (1,5 porcento). A detecçäo de, pelo menos, uma alteraçäo metabólica encontrada na grande maioria dos pacientes avaliados comprova a eficácia do protocolo aplicado nesse trabalho. O estudo sugere que a elevada prevalência de alteraçöes metabólicas associadas à litíase renal justifica a investigaçäo sistemática dos pacientes litiásicos. O estabelecimento de centros regionais com serviço de litíase renal deverá näo só favorecer aos pacientes dessas regiöes, bem como contribuir, no sentido epidemiológico, para um maior conhecimento dessa doença no Brasil.(au)

Idiopathic calcium nephrolithiasis.

Calcium nephrolithiasis (CaNL) accounts for more than 70% of all renal stones, and its prevalence has increased in the last decades. Under this definition are included patients passing stones, composed of calcium oxalates and/or calcium phosphates. Current views of the pathogenesis of CaNL are based on the role of metabolic abnormalities which concur to render urines more conducive to crystallization. Therefore, the diagnostic approach is aimed at detecting these abnormalities, and the medical treatment assumes that a decrease in the risk of lithogenesis will result in remission or improvement of recurrences. The workup of the patients with CaNL begins with the analysis of passed stones and X-ray, sonography or other imaging techniques. Eligible patients, that is, both recurrent active stone formers and single-stone formers with individual risk factors, are considered for a metabolic evaluation, by which a number of blood and urine parameters are measured and others calculated. These include estimates of urine state of saturation with calcium and uric acid salts, net gastrointestinal alkali absorption, renal threshold of phosphate and other renal clearances and net acid and total nitrogen excretions. Basically, this screening is informative on renal function, metabolic abnormalities and their pathophysiology, risk of stone formation and dietary habits. During treatment it gives information about patient compliance and adverse effects of therapy. The cost of a comprehensive screening in Piedmont is 192,000 ITL (100 Euro) and rises to 300,000 ITL (154 Euro) if hormones and hydroxyproline are measured. In individual patients second- and third-level studies are performed, in order to detect systemic diseases which account for about 20% of CaNL in our series. Cost-to-benefit analysis has shown that the medical procedures for CaNL yield considerable saving in terms of difference between expenditure for drugs and testing and reduction of stone events. However, the current workup cannot be considered exhaustive, because misleading events may hamper the relation between laboratory findings and clinical outcome, and factors other than urine composition have appeared on the scenario of nephrolithiasis. These represent our challenge for the third millennium.