Caracterização mineralógica e geoquímica de cálculos renais

Abstract

Resumo: Calculos renais sao depositos de minerais formados no sistema urinario devido a supersaturacao urinaria, pH, habitos alimentares, hereditariedade, dureza da agua, participacao de bacterias no organismo, entre outros. A composicao mineralogica mais comum dos calculos sao oxalatos de calcio (Whewellita e Weddelita), fosfatos de calcio (grupo da apatita, whitlockita e brushita), alem da estruvita, e compostos organicos como a cistina e a uricita. O objetivo da pesquisa e associar as caracteristicas morfologicas e mineralogicas dos calculos renais a fim de facilitar a identificacao dos calculos e auxiliar no tratamento dos pacientes, alem de verificar se a alimentacao e a agua ingerida influenciam ou nao na formacao dos calculos. Na pesquisa foram estudadas 160 amostras provenientes de pacientes atendidos no Hospital das Clinicas da Universidade Federal do Parana na cidade de Curitiba, Estado do Parana, e as descricoes e analises mineralogicas, quimicas e isotopicas foram realizadas no Laboratorio de Analises de Minerais e Rochas (LAMIR), do Departamento de Geologia da Universidade Federal do Parana. A analise da composicao mineral foi realizada pela tecnica de Difratometria de raios X (DRX) e o resultado indicou que 11% dos calculos renais estudados sao polimineralicos (formados por mais de dois minerais), 37% sao bimineralicos e os 52% restantes sao monomineralicos. A whewellita representa cerca de 57% das amostras analisadas, 17% sao constituidas por estruvita e 10% por estrutura cristalina organica, denominada uricita ou acido urico. Alem desses, ocorrem minerais de wheddellita, apatita, cistina, whitlockita, brushita e quartzo. A composicao quimica de seis calculos, obtida atraves da tecnica de Fluorescencia de Raios X (FRX), mostrou que a maioria deles possuem fosfato de calcio, alem de magnesio, sodio e enxofre. A analise isotopica de carbono e oxigenio mostrou diferentes resultados entre os calculos, compostos predominantemente por whewellita, estruvita e apatita, com valores de ƒÂ13C entre -24 e -8ñ e ƒÂ18O entre -12 e -6ñ. Os resultados indicaram que para algumas especies minerais e possivel distinguir os calculos, baseando-se na sua dureza e cor. A associacao dos aspectos morfologicos e mineralogicos pode ser feita para determinados minerais de forma satisfatoria e os resultados da DRX e FRX confirmam a predominancia dos oxalatos e fosfatos de calcio. Os resultados isotopicos indicam que possivelmente ha influencia da alimentacao e da agua na formacao dos calculos renais

Abstract: Kidney stones are mineral deposits generated in urinary system by urinary supersaturation, pH, eating habits, genetic, water hardness, bacterial influence in human organism and other factors. The most common minerals in kidney stones are calcium oxalates (Whewellite and Weddellite), calcium phosphates (apatite group, whitlockite and brushite), besides struvite and chemical compounds such as cystine and uric acid. The purpose of this study is associate morphological and mineralogical characteristics of kidney stones in order to simplify their identification process and support the patientsf medical treatment, besides to verify the influence of a personfs diet and water intake in stone formation. We have studied 160 samples from patients treated in Hospital das Clinicas of Curitiba-PR and the morphological, mineralogical, chemical and isotopic analyses were done at Laboratorio de Analises de Minerais e Rochas (LAMIR), from Geology Department of Federal University of Parana. The mineralogical composition analysis was done by X Ray Diffraction (XRD) technique and its results have indicated that 11% of stones are polymineralic (stones formed by more than 2 minerals); 35% are bimineralic and 54% are monomineralic. The whewellite stone represents 64% of the samples, 14% are uric acid or uricite, an organic crystal structure, and 10% are struvites. Besides these minerals, weddellite, apatite, cystine, whitlockite, brushite and quartz also occur. The chemical composition of six samples obtained by X Ray Fluorescence (XRF) has shown that most of the kidney stones are comprised by calcium phosphates, besides magnesium, sodium and sulfur. Isotopic analyses of carbon and oxygen isotopes have shown different results between the kidney stones formed mainly by whewellite, struvite and apatite, whose ƒÂ13C values range from -23 to -8ñ and ƒÂ18O values range between -12 e -6ñ. The results have indicated that for some mineral species in kidney stones it is possible to distinguish them, based in their relative hardness and color. The association of mineralogical and morphological aspects can be done satisfactorily for specific kidney stones minerals and the results obtained by XRD and XRF confirmed the dominance of calcium phosphates and oxalates stones. The isotopic results have been indicated that probably food and water intake influence in the generation of kidney stones