The role of urea-induced osmotic diuresis and hypernatremia in a critically ill patient: case report and literature review / O papel da diurese osmótica induzida por ureia na geração de hipernatremia no paciente crítico: relato de caso e revisão da literatura

Abstract Hypernatremia is a common electrolyte problem at the intensive care setting, with a prevalence that can reach up to 25%. It is associated with a longer hospital stay and is an independent risk factor for mortality. We report a case of hypernatremia of multifactorial origin in the intensive care setting, emphasizing the role of osmotic diuresis due to excessive urea generation, an underdiagnosed and a not well-known cause of hypernatremia. This scenario may occur in patients using high doses of corticosteroids, with gastrointestinal bleeding, under diets and hyperprotein supplements, and with hypercatabolism, especially during the recovery phase of renal injury. Through the present teaching case, we discuss a clinical approach to the diagnosis of urea-induced osmotic diuresis and hypernatremia, highlighting the utility of the electrolyte-free water clearance concept in understanding the development of hypernatremia.

Resumo A hipernatremia é um distúrbio eletrolítico comum no ambiente de terapia intensiva, com uma prevalência que pode chegar a 25%. Está associada a maior tempo de internação hospitalar e é um fator de risco independente para a mortalidade. Este relato ilustra um caso de hipernatremia de origem multifatorial no ambiente de terapia intensiva. Destacaremos o papel da diurese osmótica por geração excessiva de ureia, uma causa de hipernatremia pouco conhecida e subdiagnosticada. Este cenário pode estar presente em pacientes em uso de elevadas doses de corticoides, com sangramento gastrointestinal, em uso de dietas e suplementos hiperproteicos e estado de hipercatabolismo, especialmente durante a fase de recuperação de injúria renal. A seguir, discutiremos uma abordagem clínica para o diagnóstico da hipernatremia secundária à diurese osmótica induzida por ureia, destacando a importância do conceito de clearance de água livre de eletrólitos nesse contexto.

Endogenous nitrogen excretion in alcoholic patients on an enteral diet

1. Obligatory nitrogen losses were evaluated in a group of 9 chronic alcoholic adult males of low socioeconomic status, with an intake of approximately 1 liter/day of a Brazilian beverage (45% ethanol by weight) for at least 5 years. 2. The patients were fed a nitrofen-free diet orally or by tube for 7 days. Since endogenous nitrogen excretion was statistically similar for all subjects, the data wee pooled for overall analysis. 3. a stable rate of urinary nitrogen output of 28.42 ñ 11.93mg N Kg-1 day-1 was reached in about 3 days both after oral and tube feeding. The obligatory fecal losses for days 4 to 7 were 17.20 ñ 8.86 mg NKg-1 day-1. 4. Based on the factorial approach, considering the skin and other minor nitrogen losses to be 10 mg NKg-1 day-1, the total endogenous obligatory nitrogen loss for this group of alcoholic patients was 55.62 ñ 18.57 mg NKg-1 day-1. 5. The present results are discussed on the basis of the controversy about the nitrogen requirement of alcoholic patients. The endogenous nitrogen excretion demonstrated does not suggest the need for increased nitrogen intake, but the protein malnutrition of the patients points to the need for more protein