Disfunción renal en el paciente cirrótico / Renal dysfunction in the cirrhotic patient

La disfunción renal es una complicación común en pacientes con cirrosis avanzada y está asociadaa un incremento significativo en la mortalidad. Este deterioro de la función renal puede ser reversible en algunos casos, si se identifica y se trata su etiología. La lesión renal aguda (LRA) de origen prerrenal y la necrosis tubular aguda (NTA) son las entidades más frecuentes en pacientes con enfermedad hepática crónica y cirrosis, constituyendo un desafío en los escenarios clínicos actuales. La aparición de nuevos biomarcadores como la lipocalina asociada a la gelatinasa de neutrófilos (NGAL), puede ser un factor determinante para esclarecer el origen de estas dos entidades. En la actualidad, la clasificación de la enfermedad renal establece que un aumento en la creatinina sérica basal >0,3 mg/dL dentro de las primeras 48 horas, o un incremento mayor al 50% desde la línea de base, son suficientes para definir lesión renal aguda, por lo cual, cambios leves en la creatinina sérica en un periodo corto de tiempo, contribuyen a una identificación temprana y previenen desenlaces negativos. Esta revisión de tema abordará la lesión renal aguda en cirrosis desde la fisiopatología, la clasificación actual según guías internacionales, los avances en biomarcadores y las principales etiologías, finalizando con un abordaje general y estrategias de prevención.

Kidney dysfunction is a common complication in patients with advanced cirrhosis and is associated with a significant increase in mortality. This deterioration of kidney function may be reversible in some cases, if its etiology is identified and treated. Acute kidney injury (AKI) of prerenal origin and acute tubular necrosis (ATN) are the most frequent entities in patients with chronic liver disease and cirrhosis, constituting a challenge in current clinical scenarios. The emergence of new biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), may be a determining factor in clarifying the origin of these two entities. Currently, the classification of renal disease establishes that an increase in basal serum creatinine >0,3 mg/dL within the first 48 hours, or an increase higher than 50% from the baseline, are enough to define acute kidney injury, therefore slight changes in serum creatinine in a short period of time contribute to an early identification and prevent negative outcomes. This literature review will address acute kidney injury in cirrhosis from its pathophysiology, current classification according to international guidelines, advances in biomarkers and the main etiologies associated with it, ending with a general approach and prevention strategies.

Patogenia, diagnóstico y tratamiento de la disfunción renal en cirrosis / Pathogenesis, Diagnosis and Treatment of Renal Dysfunction in Cirrhosis

Los pacientes con cirrosis hepática son susceptibles a presentar un deterioro de la función renal que puede ser de naturaleza funcional y/o estructural. La insuficiencia renal aguda (IRA) prerrenal representa la forma más frecuente en el 68% de los casos, e incluye un tipo especial de insuficiencia renal funcional conocida como síndrome hepatorrenal (SHR). La creatinina sérica permanece como el mejor biomarcador de IRA en cirrosis a pesar de sus reconocidas limitaciones. La diferenciación entre necrosis tubular aguda (NTA) y SHR se puede establecer con el uso de biomarcadores urinarios como la uNGAL. Los factores de riesgo de IRA en cirrosis incluyen las infecciones bacterianas, la hemorragia digestiva, las pérdidas de líquidos gastrointestinales y renales, la paracentesis sin albúmina y los agentes nefrotóxicos, entre otros. Los nuevos criterios por estadios de la AKI-IAC para el diagnóstico de IRA en cirrosis, que inician por un aumento de la creatinina sérica ≥0,3 mg/dL en menos de 48 horas, mejoran el pronóstico de los pacientes al permitir una intervención más temprana. El diagnóstico del SHR se establece al excluir las causas de azoemia prerrenal, NTA y expandir el volumen con albúmina. El uso de vasoconstrictores esplácnicos, como la terlipresina junto con la albúmina, permite revertir hasta el 40% de los casos de SHR. El trasplante hepático representa el tratamiento definitivo en pacientes con SHR.

Patients with cirrhosis of the liver are susceptible to deterioration of renal function which may be functional or structural. Prerenal acute renal failure which occurs in 68% of these cases is the most common form. It includes a special type of functional renal failure known as hepatorenal syndrome (HRS). Serum creatinine remains the best biomarker for acute renal failure in cirrhosis despite its recognized limitations. Acute tubular necrosis and HRS can be differentiated by using urinary biomarkers such as urinary neutrophil gelatinase-associated lipocalin (uNGAL). Risk factors for acute renal failure in cirrhosis include bacterial infections, gastrointestinal bleeding, loss of gastrointestinal and renal fluids, paracentesis without albumin, and nephrotoxic agents. The new criteria for staging acute kidney injury (AKI) in cirrhosis have improved patient outcomes by enabling earlier interventions by starting when serum creatinine increases above 0.3 mg/dl in less than 48 hours. The diagnosis of HRS is established by excluding causes of pre-renal azotemia, acute tubular necrosis and volume expansion with albumin. The use of splanchnic vasoconstrictors such as terlipressin together with albumin can reverse up to 40% of cases of SHR. Liver transplantation is the definitive treatment for patients with hepatorenal syndrome.

Hepatorenal syndrome: an update

Hepatorenal syndrome (HRS) is the development of renal failure in patients with chronic previous liver disease, without clinical or laboratory evidence of previous kidney disease. It affects up to 18 percent of cirrhotic patients with ascites during the first year of follow-up, reaching 39 percent in five years and presenting a survival of about two weeks after its establishment. HRS diagnosis is based on clinical and laboratory data. The occurrence of this syndrome is related to the mechanism for ascites development, involving vasoconstriction, low renal perfusion, water and sodium retention, increased plasma volume, and consequent overflow at the splanchnic level. Renal vasoactive mediators like endothelin 1, thromboxane A2, and leukotrienes are also involved in the genesis of this syndrome, which culminates in functional renal insufficiency. The treatment of choice can be pharmacological or surgical, although liver transplantation is the only permanent and effective treatment, with a four-year survival rate of up to 60 percent. Liver function recovery is usually followed by renal failure reversion. Early diagnosis and timely therapeutics can increase life expectancy for these patients while they are waiting for liver transplantation as a definitive treatment.

A síndrome hepatorrenal (SHR) é o desenvolvimento do quadro de insuficiência renal em pacientes com doença hepática crônica prévia sem evidências clínica ou laboratorial de nefropatia prévia. Atinge até 18 por cento dos pacientes cirróticos com ascite em um ano, chegando a 39 por cento em cinco anos, com uma sobrevida média em torno de duas semanas após estabelecido o quadro. O diagnóstico da SHR baseia-se em critérios clínicos e laboratoriais. Seu aparecimento está relacionado ao mecanismo de formação de ascite, que envolve vasoconstrição e hipofluxo renal, retenção de água e sódio, aumento do volume plasmático, e conseqüentemente hiperfluxo no território esplâncnico. Mediadores vasoativos renais e humorais, como a endotelina 1, tromboxano A2 e leucotrienos, estão ainda envolvidos na gênese desta síndrome que culmina com insuficiência renal funcional. O tratamento preconizado da SHR pode ser farmacológico ou cirúrgico, sendo o transplante de fígado o único efetivo e permanente, com sobrevida de até 60 por cento em quatro anos. Após melhora da função hepática, geralmente há a reversão da insuficiência renal. O diagnóstico precoce e a rápida terapêutica podem ampliar a expectativa de vida destes hepatopatas enquanto se aguarda o transplante hepático para seu tratamento definitivo.