Nutrition and Ischemic Stroke

As a registered dietitian working in a neurology intensive care unit, I took interest in the results of the study by Yoo et al¹ published in the January 2008 issue of the Archives regarding the effect of undernutrition on clinical outcome in ischemic stroke patients. As an advocate of evidence-based nutrition and medicine, I am concerned by the lack of evidence-based criteria used to diagnose undernutrition in this study.

Low serum levels of albumin, prealbumin, and transferrin were 3 of the 5 parameters selected to assess nutritional status in the Yoo et al¹ study. Decades of published evidence, however, indicate these hepatic proteins are neither sensitive nor specific to nutritional status.² After an injury (including brain tissue damage in ischemic stroke), a patient's inflammatory response to stress results in an increased production of cytokines that act to suppress production of the “negative” acute-phase hepatic proteins (albumin, prealbumin, and transferrin),³ increase production of the “positive” acute-phase proteins (C-reactive protein, for example),³ and increase capillary permeability resulting in a redistribution of hepatic proteins from the intravascular to extravascular space.⁴ These acute-phase responses are independent of nutritional status. Additionally, other factors affect serum levels of these visceral proteins: position (standing vs recumbent), renal disease, liver disease, medications, iron status, and hydration status.^{2 ,4}

I applaud the authors of the study for investigating the possible role of undernutrition on clinical outcomes in ischemic stroke patients. But a patient's nutritional status can not be determined by measuring serum albumin, prealbumin, or transferrin. These visceral proteins may instead be useful as indicators of inflammatory processes.² Meaningful conclusions regarding the effect of undernutrition on patient outcome can be drawn only if we use the most evidence-based nutrition assessment parameters to define nutritional status. Yoo et al suggest that strategic nutritional support in undernourished stroke patients may improve clinical outcomes.¹ A critical step in any future studies designed to answer this question is to ensure undernutrition is accurately diagnosed.

Correspondence: Ms Kliewer, Food and Nutrition Services, OSF Saint Francis Medical Center, 530 NE Glen Oak Ave, Peoria, IL 61637 (kara.l.kliewer@osfhealthcare.org).

Financial Disclosure: None reported.