Bases fisiológicas da nefrologia / Physiological bases of nephrology

O livro tem sua inspiração no Curso de Bases Fisiológicas de Prática Médica da Faculdade de Medicina da Universidade de São Paulo – USP, capítulo Nefrologia. Seu texto passou por sucessivas modificações didáticas e de conteúdo, ao longo dos 18 anos de existência do curso. Amadureceu, encorpou, ganhando aspecto interdisciplinar ao interagir a Fisiologia – centrada nos mecanismos de funcionamento de órgãos e sistemas, com a prática clínica dirigida à interpretação de dados clínico laboratoriais e a aplicação do raciocínio diagnóstico. É livro, pois, que bem reflete a excelência do ensino da Nefrologia integrado pela Fisiologia, Fisiopatologia Renal, Investigações clínicas e Exames Complementares. Sua equipe autorial é formada por 1 Editor, 2 Coeditores e 14 Colaboradores. Apresenta 15 capítulos e 3 Apêndices. É destinado aos estudantes de graduação de Medicina, Médicos Residentes e profissionais interessados em reciclar e atualizar seus conhecimentos em Nefrologia.

Bases fisiológicas da nefrologia

O livro tem sua inspiração no Curso de Bases Fisiológicas de Prática Médica da Faculdade de Medicina da Universidade de São Paulo – USP, capítulo Nefrologia. Seu texto passou por sucessivas modificações didáticas e de conteúdo, ao longo dos 18 anos de existência do curso. Amadureceu, encorpou, ganhando aspecto interdisciplinar ao interagir a Fisiologia – centrada nos mecanismos de funcionamento de órgãos e sistemas, com a prática clínica dirigida à interpretação de dados clínico laboratoriais e a aplicação do raciocínio diagnóstico. É livro, pois, que bem reflete a excelência do ensino da Nefrologia integrado pela Fisiologia, Fisiopatologia Renal, Investigações clínicas e Exames Complementares. Sua equipe autorial é formada por 1 Editor, 2 Coeditores e 14 Colaboradores. Apresenta 15 capítulos e 3 Apêndices. É destinado aos estudantes de graduação de Medicina, Médicos Residentes e profissionais interessados em reciclar e atualizar seus conhecimentos em Nefrologia

Sodio, potasio e hipertensión arterial / Sodium, potassium and hypertension

La hipertensión arterial tiene una prevalencia cercana al 30 por ciento en la población adulta chilena y es la mayor causa de muerte en el mundo. La hipertensión primaria resulta de la interacción de distintos factores tanto genéticos, como funcionales renales y en particular un estilo de vida poco saludable. En este artículo se describe la influencia del exceso de sodio y el déficit de potasio, característicos de nuestra alimentación, en el desarrollo de hipertensión. Se revisan los estudios observacionales más importantes, los mecanismos fisiopatológicos para explicar el rol dañino del exceso de sodio y el déficit de potasio y finalmente se hacen recomendaciones para adecuar su consumo con el fin de prevenir hipertensión y sus complicaciones.

Arterial hypertension has a prevalence of about 30 percent in the adult Chilean population and it is the major cause of mortality worldwide. Primary hypertension results from the interaction of genetic factors, functional renal impairment and particularly from an altered life style. This article describes the impact of the excess of sodium and the deficit of potassium of our usual alimentation in the development of hypertension. In this setting, some important observational studies and physiopathological mechanisms were discussed, and finally some recommendations to reduce sodium and to increase potassium intake to prevent hypertension and vascular complications, were made.

Disorders of Potassium Metabolism

Hypokalemia usually reflects total body potassium deficiency, but less commonly results from transcellular potassium redistribution with normal body potassium stores. The differential diagnosis of hypokalemia includes pseudohypokalemia, cellular potassium redistribution, inadequate potassium intake, excessive cutaneous or gastrointestinal potassium loss, and renal potassium wasting. To discriminate excessive renal from extrarenal potassium losses as a cause for hypokalemia, urine potassium concentration or TTKG should be measured. Decreased values are indicative of extrarenal losses or inadequate intake. In contrast, excessive renal potassium losses are expected with increased values. Renal potassium wasting with normal or low blood pressure suggests hypokalemia associated with acidosis, vomiting, tubular disorders or increased renal potassium secretion. In hypokalemia associated with hypertension, plasam renin and aldosterone should be measured to differentiated among hyperreninemic hyperaldosteronism, primary hyperaldosteronism, and mineralocorticoid excess other than aldosterone or target organ activation. Hypokalemia may manifest as weakness, seizure, myalgia, rhabdomyolysis, constipation, ileus, arrhythmia, paresthesias, etc. Therapy for hypokalemia consists of treatment of underlying disease and potassium supplementation. The evaluation of hyperkalemia is also a multistep process. The differential diagnosis of hyperkalemia includes pseudohypokalemia, redistribution, and true hyperkalemia. True hyperkalemia associated with decreased glomerular filtration rate is associated with renal failure or increased body potassium contents. When glomerular filtration rate is above 15 mL/min/1.73m2, plasma renin and aldosterone must be measured to differentiate hyporeninemic hypoaldosteronism, primary aldosteronism, disturbance of aldosterone action or target organ dysfunction. Hyperkalemia can cause arrhythmia, paresthesias, fatigue, etc. Therapy for hyperkalemia consists of administration of calcium gluconate, insulin, beta2 agonist, bicarbonate, furosemide, resin and dialysis. Potassium intake must be restricted and associated drugs should be withdrawn.

Influencia del género y la percepción de la imagen corporal en las conductas alimentarias de riesgo en adolescentes de Mérida / Influences of gender and body image perception in risk eating disorders in adolescents in Mérida

Este estudio tuvo como objetivo analizar la influencia del género y la percepción de la imagen corporal en las conductas alimentarias de riesgo asociadas con los trastornos de la conducta alimentaria en adolescentes del primero y segundo año de educación media y diversificada en ocho instituciones educativas públicas del Municipio Libertador estado Mérida Venezuela, seleccionadas de forma intencional. Se realizó un estudio de campo, descriptivo, en el cual participaron 421 adolescentes, 56.5 por ciento varones y 43.5 por ciento hembras, el promedio de edad para los varones fue 15.75 ± 1.05 años y para las hembras 15.80 ±1.07 años. Para la recolección de los datos de imagen corporal se diseñó y se validó un instrumento donde el participante seleccionó entre cuatro alternativas la opción que más representaba su condición para el momento. El 57,5 por ciento, se percibió normal, 30.6 por ciento como delgados; y el 11,9 por ciento con sobrepeso. No se reportó percepción de imagen corporal obesa. La imagen corporal normal y delgada fueron percibidas entre los adolescentes con una frecuencia más alta en los varones (32,5 por ciento), mientras que la percepción de la imagen con sobrepeso fue más frecuente en las hembras (7,4 por ciento). El registro de la conducta alimentaria se realizó a través de un cuestionario diseñado y validado por expertos constituidos por nutricionistas, sociólogos y psicólogos clínicos en el que solicitó al entrevistado reportar la conducta alimentaria practicada para el control del peso en los últimos seis meses. Los hallazgos permiten confirmar que las mujeres cuya percepción de su imagen se caracteriza por el exceso, presentan mayor riesgo asociado con los trastornos de la conducta alimentaria (9,586 F=2 p=0,008) (12,622 F=5 p=0,027).

The object of this study was to analyze the influence of gender and body image perception in risk eating conducts associated with the upheavals of eating disorders in adolescents of first and second year of highschool in eight public institutions of the Municipio Libertador in Merida Venezuela, They were selected in an intentional form. A descriptive field, was performed, in which 421 adolescents participated, 56,5% men and 43,5% females, the average of age for the 15,75 men was ± 1,05 years and for 15,80 females ± 1.07 years. For the gathering of the corporal Image data, an instrument was designed and validated, In this the participant chose between four alternatives the option that represented more his/her condition at the moment, 57.5%, perceived themselves as normal, 30.6%, as thin; and 11.9% with overweight. The perception of obese corporal image was not reported. The normal and thin body image were perceived among the adolescents with a higher frequency in men 32.5%, whereas the perception of the image with overweight was more frequent in the females (7.4%). The registry of eating disorders was done through a questionnaire designed and validated by a group of experts constituted by dietitians, sociologists and clinical psychologists in which the interviewed was asked in person to report the eating conduct practiced for the control of weight during the previous six months. The findings allow us to confirm that women whose perception of their image is characterized by the excess present major risks associated with the upheavals of the eating disorders (9,586 F=2 p=0,008 (12,622 F=5 p=0,027).

Alterações hidroeletrolíticas agudas ocorridas no Triatlon Ironman Brasil / Acute hydroelectrolytic changes occurred in the Brazilian Ironman Triathlon

O Triatlon Ironman caracteriza-se por ser uma atividade de resistência constituída por 3,8km de natação, 180km de ciclismo e 42,2km de corrida, no qual o atleta exercita-se, em média, por cerca de 13 horas. Neste contexto, o atleta exposto a tal carga de esforço e adversidades ambientais, experimenta alterações orgânicas agudas em seus sistemas biológicos, incluindo os distúrbios hidroeletrolíticos. O objetivo deste estudo é descrever as alterações hídricas e eletrolíticas encontradas em atletas de triatlon Ironman. De 2002 a 2005 foram avaliados 109 atletas voluntários antes e imediatamente após as provas realizadas em Florianópolis-SC Brasil, com análise sanguínea dos eletrólitos sódio, e potássio, e medida de massa corporal. Os dados do sódio sérico de 89 atletas foram correlacionados com o grau de desidratação e modificações percentuais de peso corporal. Dados de 77 atletas, quanto ao potássio sérico, foram avaliados isoladamente de forma descritiva. Seis atletas (6,7 por cento) apresentaram-se euhidratados ou superhidratados ao final da prova, 50 atletas desidrataram de 0 a 3 por cento (56,2 por cento), 29 de 3 a 6 por cento (32,6 por cento) e 4 atletas (4,5 por cento) desidrataram mais que 6 por cento. Houve uma tendência a ocorrer hiponatremia entre aqueles que desidrataram menos ou ganharam peso. O potássio teve um comportamento dentro dos limites da normalidade em toda amostra. Conclui-se que os distúrbios hidroeletrolíticos (hiponatremia e desidratação) são incidentes nesta modalidade esportiva, sendo a superhidratação a etiologia provável da hiponatremia denotada pelo ganho ou perdas discretas de peso.

The Ironman Triathlon is characterized for being an endurance activity consisting of 3.8 km of swimming, 180 km of cycling and 42.2 km of running, in which the athlete exercises an average of about 13 hours. In this context, the athlete exposed to such load of effort and environmental adversities, experiences acute organic alterations in his biological systems, including hydroelectrolytic disturbs. The objective of this study is to describe the hydric and electrolytic alterations found in Ironman triathlon athletes. From years 2002 to 2005, 109 volunteer athletes have been evaluated before and immediately after the events which took place in Florianópolis-SC Brazil, with blood analysis of sodium and potassium electrolytes, and body mass measurement. Sodium serum data from 89 athletes have been correlated with the degree of dehydration and percentage alterations of body weight. Data of 77 athletes concerning the serum potassium were separately evaluated in a descriptive way. Six athletes (6.7 percent) were euhydrated or superhydrated at the end of the test; 50 athletes were dehydrated from 0 to 3 percent (56.2 percent); 29 from 3 to 6 percent (32.6 percent) and 4 athletes (4.5 percent) were dehydrated more than 6 percent. There was a tendency to hyponatremia among those who had dehydrated less or gained weight. Potassium behaved within the limits of normality in the entire sample. It was concluded that hydroelectrolytic disturbs (hyponatremia and dehydration) are recurrent in this sportive modality, being superhydration the probable etiology of hyponatremia denoted from profit or small weight loss.

Cloning and Expression of Sodium-Bicarbonate Cotransporter Isoform in Rat / 대한해부학회지

The potassium depletion has remarkable and opposite effect on kidney and body growth and has affected the expression of the several ion transporters. Previously, Ahn et al. have reported that HK alpha 1 and 2 subunit gene were upregulated in the hypokalemic rat kidney. To clone the unreported genes expressed in potassium deficiency, differential display PCR-based cloning strategy was used in normal and potassium-depleted rat kidney and a novel gene was isolated. Sequence analysis with blast search program identified a cDNA clone encoding an isoform of kidney sodium bicarbonate cotransporter-1. The tissue and cellular expression pattern of this gene were investigated with Northern analyses and in situ hybridization histochemistry (ISH) in normal and hypokalemic rats. This novel transcript was highly expressed in kidney and brain and at lower levels in distal colon, urinary bladder, and heart but not in salivary gland, stomach, liver, and lung in normal rat. In potassium-depleted rat, this transcript was upregulated in kidney, brain, and distal colon. By ISH, cellular distribution of this gene was highly expressed in S3 segment of proximal tubule, distal convoluted tubule, and cortical collecting duct of kidney and lower third of intestinal glands of distal colon but at lower levels in cortical and medullary thick ascending limb and medullary collecting duct of kidney and middle third of intestinal glands of distal colon. From these results, this candidate gene may play an important role in HCO3-transport by these organs during potassium depletion.

Oscilaçöes do potássio sérico em pacientes submetidos a laparotomias / Seric potassium behavior in laparotomy submitted patients

Inúmeras pesquisas têm sido conduzidas, visando estudar o metabolismo do potássio sob os mais diferentes aspectos. O objetivo deste trabalho foi verificar o comportamento do íon potássio em pacientes submetidos a laparotomias. Foram estudados 53 pacientes operados com anestesia geral (cirurgias de médio e grande portes), avaliando-se a variação individual deste íon no pré e pós-operatório imediato e comparando-se com o grupo-controle de 20 pacientes submetidos à herniorrafia inguinal e 20 doentes internados por infarto agudo do miocárdio no Hospital Municipal de Santo André-São Paulo, ligado à FMABC. Observou-se no grupo das laparotomias, queda do potássio em 47,2 por cento, resultado estatisticamente significante, quando comparado com o grupo dos IAM (30 por cento) e das herniorrafias (10 por cento). Esta queda, porém, apenas ultrapassou os valores mínimos da normalidade em 32 por cento dos casos, sendo esta diferença não significante, concluindo-se que a reposição deste íon deva estar relacionada à sua dosagem no POI

Potassium, sodium and magnesium contents in skeletal muscle of renal stone-formers: a study in an area of low potassium intake.

Skeletal muscles surgically obtained from the stone-former group (external oblique muscle; n = 202, 82 males & 120 females), control group I (external oblique muscle; n = 5, all males), control group II (rectus abdominis muscle; n = 23, all females) and control group III (quadriceps femoris muscle; n = 11, all males) were analyzed for potassium (K), sodium (Na) and magnesium (Mg) contents. Muscle samples were digested with 65 per cent HNO3 and determined for K, Na and Mg by an atomic absorption spectrophotometer. The results of analysis showed the mean K, Na and Mg (+/- S.D.) contents in mumol per one gram of fresh tissue of the stone-former group, control groups I, II and III were 73.5 +/- 16.6, 51.3 +/- 13.4 and 6.6 +/- 1.3, 77.5 +/- 3.9, 43.9 +/- 9.9 and 7.2 +/- 0.5, 83.8 +/- 27.5, 49.4 +/- 24.1 and 6.7 +/- 1.8 and 85.0 +/- 17.1, 48.5 +/- 12.1 and 6.8 +/- 1.3. Among these variables, only the K content of control group III was higher significantly (p < 0.05) than that of the stone-former group. In the stone-former group, regression analysis showed significant correlations between K and Mg contents (r = 0.856, p < 0.001) and K and Na contents (r = -0.325, p < 0.001). Due to no available data of the external oblique, we made a comparison of our results to the soleus type of skeletal muscle of normal subjects reported by Dorup et al and found that the external oblique muscle had lower mean contents of K and Mg but a higher Na content than those of the soleus. Our results were similar to the K and Mg depleted muscles obtained from the patients receiving long-term treatment with diuretic drugs. The results suggest that most of our subjects in both the stone-former and the 3 control groups were in a state of K and Mg depletion. The causes may be multifactorial, for instance low intake, high sweat loss and the existence of environmental inhibitor (s) for K transport like vanadium.

Variaçöes dos níveis séricos de sódio, potássio e glicose de cäes em choque séptico / Sodium, potassium and glucose serum levels changes in dogs with endotoxic shock

Foram avaliados os níveis séricos de sódio, potássio e glicose em trinta e cinco cäes, machos e fêmeas, que se apresentaram em estado de choque séptico decorrente da gastrenterite hemorrágica, antes e após terapia sintomática (Ringer com lactato de sódio e glicose), com a finalidade de se derterminar a melhora clínica obtida. Observou-se que 74,2 por cento dos animais apresentavam hipocalemia, 57,1 por cento hipoglicemia e 60 por cento discreta hiponatremia, quando da primeira colheita. Após 2 horas da instituiçäo da terapia sintomática, observou-se que a hipopotassemia ainda persistia, porém a hipoglicemia fora suficientemente corrigida (apenas 5,8 por cento mantiveram-se hipoglicêmicos). Conclui-se que a terapia sintomática é efetiva para a correçäo dos valores glicêmicos, porém näo é capaz de repor a deficiência de potássio apresentada por estes animais, devendo ser entäo acrescida deste íon.

Nefropatía tubular por carencia prolongada de potasio / Tubular nephropathy from chronic potassium deficiency

Fueron estudiados 2 casos con desnutrición crónica avanzada e hipokalemia acentuada en los cuales se encontraron disminución de la filtración glomerular y del flujo renal plasmático, presencia de poliuria con hiposmolaridad sérica e hipotonía urinaria, las cuales no se modificaron durante la administración de hormona antidiurética. Uno de dichos casos tuvo una evolución fatal, a pesar de la administración de suplemento de potasio por vía oral, y el estudio histopatológico de sus riñones demostró la conservación de los glomérulos y la presencia de degeneración vacuolar hidrópica en el epitelio de los túbulos proximales. El otro caso evolucionó favorablemente hacia la recuperación y un nuevo estudio practicado al mes de su ingreso demostró la normalización de sus alteraciones fisiopatológicas. Tanto las alteraciones anatómicas, como las funcionales se han descrito en diversas condiciones patológicas que tienen en común la pérdida crónica de potasio por diferentes vías. Se ha observado la reversibilidad de estas lesiones pero igualmente existe la posibilidad de una falta de respuesta a la administración de potasio y la evolución hacia la insuficiencia renal y a la muerte. El curso del trastorno puede estar condicionado por la intensidad y la duración de la depleción de potasio. Los estudios experimentales en que se ha impedido la aparición de estas lesiones en ratas deplecionadas de potasio que recibían rubidio y cesio, así como la desaparición de las lesiones ya presentadas con la administración de estos elementos, han sugerido que no sea propiamente la deficiencia de potasio la responsable directa de esta neforpatía, sino

Potassium contents of northeastern Thai foods.

From our previous nutritional assessment, low potassium (K) intake among northeastern Thai males has been clearly demonstrated. This prompted us to undertake a survey of the K content of local foods. Food samples comprised of 57 animal and 142 plant products which were collected from various places in the northeast of Thailand. The dry ashing method was used to prepare the samples for K analysis using an atomic absorption spectrophotometer. Foods could be divided into 7 groups according to their K levels. Foods containing K > or = 1000 mg per 100 g fresh food were categorized in group 1. These were mainly foods in the legume group, i.e., soybean, cowpea and mungbean. While rice (polished) and rice products, the main staple, were in group 7, the lowest K group of less than 100 mg per 100 g fresh food. Comparison studies of the natural foods between those collected from the northeast and from the central regions of the country, and between the cooked foods purchased from the rural villages and from the urban areas of Khon Kaen municipality, showed that, for most food items, the K content was similar wherever it came from. However, when the K content in various parts or in different stages of growth of the same kind of plants or animals was compared, a great variation was clearly seen, for example, young tamarind leaves contained K in group 6 whereas ripe tamarind fruit contained K in group 1. According to our food consumption data, the analysis of food components of 48 meals taken during the hot season by 13 rural volunteers revealed that food items eaten with the highest frequencies and in the largest amount were those in the low K food groups, i.e., glutinous rice (group 7) and green papaya (group 6). Our results suggest that the low K intake of these northeast rural Thai people is not due to a low K content of foods in this region, but rather that their food habits and low socioeconomic status restricts consumption of those food items with higher K contents.

Parálisis periódica hipokalémica: informe de dos casos / Hipokalaemic periodic paralysis: report two cases

Cuando la potasemia desciende por debajo de 3mmol/L, se manifiesta clínicamente con flacidez y debilidad muscular, ascendente por lo general y rápidamente progresiva. Se presenta la experiencia con dos pacientes del sexo masculino que presentaron parálisis periódica hipokalémica esporádica, diagnosticada con base en intensas alteraciones musculares caracterizadas por debilidad y flacidez, potasio sérico bajo, alteraciones en la onda T, en el intervalo Q-T y la presencia de onda U del electrocardiograma, así como arritmias y la rápida respuesta favorable a la administración de potasio por vía venosa. Se enfatiza la importancia del diagnóstico y manejo de esta entidad no tan rara, pero probablemente poco diagnosticada en nuestro medio.

Relación entre las principales alteraciones metabólicas con las cardiovasculares durante el trasplante hepático / Relationship between the main metabolic and cardiovascular alterations during liver transplantation

El principal objetivo fue describir la evolución de las concentraciones de calcio iónico sanguíneo (Ca2+), potasio sanguíneo (K+) y magnesio iónico sérico (Mg2+); y su relación con las alteraciones cardiovasculares durante el trasplante ortotópico de hígado (TOH). Se estudiaron 92 pacientes adultos tratados con TOH. Se encontró una correlación inversa entre las concentraciones Mg2+ y citrato para todos los pacientes. El Mg2+ al igual que el Ca2+, es quelado por el citrato y su evolución es una imagen especular a la del citrato. En estos pacientes, no se observó ninguna disritmia que pueda ser atribuida directamente a la hipomagnesemia iónica. En conclusión, los bajos niveles preoperatorios, junto con las trasfusiones masivas de hemoderivados y el incremento de las pérdidas renales, provocan una progresiva hipomagnesemia iónica en los pacientes tratados con TOH. Se propone que la concentración de Mg2+ sea monitorizada y eventualmente tratada, al igual como se realiza con el Ca2+ y el K=