Nearly Half of Acute Stroke Patients are Dehydrated

NASHVILLE — New results have found that 44% of patients admitted for ischemic stroke are dehydrated at the time of admission, suggesting to researchers the possibility of an inexpensive and globally available treatment to optimize functional outcomes in these patients.
For the study, which was presented at the International Stroke Conference 2015, Mona N. Bahouth, MD, of Johns Hopkins Hospital, Baltimore, and fellow researchers enrolled consecutive ischemic stroke patients within 12 hours of their last normal neurological exam. Patients presented at a single academic health system, and those with renal failure or who were unable to undergo magnetic resonance imaging (MRI) were excluded.
Researchers defined dehydration as blood urea nitrogen/creatinine ratio >15 and urine specific gravity >1.010, and determined stroke severity by National Institutes of Health Stroke Scale (NIHSS) score and lesion volume by diffusion weighted MRI.
Of the 383 ischemic stroke admissions surveyed, 168 met inclusion criteria, with 75% having complete laboratory and MRI data.
At admission, 44% of patients were dehydrated. There were no reported differences in demographics between dehydrated and hydrated patients. Researchers found comparable baseline NIHSS score (P=.63) and lesion volumes (P=.48) between groups.
In addition, compared with hydrated patients, those who were dehydrated were in the worst short-term quartile of NIHSS change (42% vs. 17%; P=.02). After adjusting for age, initial NIHSS score, lesion volume and admission glucose, dehydration remained significantly associated with worst NIHSS change (OR=4.34; 95% CI 1.75-10.76).

Limitations and Implications

In his presentation, Bahouth suggested the following study limitations: small sample size; variable timing of MRI; the adequacy of perfusion techniques, which limited calculation of volumetrics; and the non-direct measure of dehydration markers.
Bahouth added that in the future, investigators should define a best approach to volume resuscitation of the dehydrated stroke patient and measure the effect on outcome, which could lead to an inexpensive, safe, and globally available intervention for the acute stroke patient.
According to Albert Favate, MD, chief of the vascular neurology department at NYU Langone Medical Center and assistant professor of neurology at NYU School of Medicine in New York, the results of this study were in line with previous observations.
“Most stroke patients are dehydrated on admission,” Favate told Neurology Advisor. “The state of dehydration can play a role in CNA perfusion, and lead to hemoconcentration and vascular sludging, exacerbating stroke.”


Objective: To determine the frequency, risk factors, and impact on the outcome of dehydration after stroke.
Methods: In this cross-sectional observational study, we included prospectively and consecutively patients with ischemic and hemorrhagic stroke. The serum Urea/Creatinine ratio (U/C) was calculated at admission and 3 days after the stroke. Dehydration was defined as U/C>80. Patients were treated in accordance with the standard local hydration protocol. Demographic and clinical data were collected. Neurological severity was evaluated at admission according to the NIHSS score; functional outcome was assessed with the modified Rankin scale score (mRS) at discharge and 3 months after the stroke. Unfavorable outcome was defined as mRS > 2.
Results: We evaluated 203 patients; 78.8% presented an ischemic stroke and 21.2% a hemorrhagic stroke. The mean age was 73.4 years ±12.9; 51.7% were men. Dehydration was detected in 18 patients (8.9%), nine patients at admission (4.5%), and nine patients (4.5%) at 3 days after the stroke. Female sex (OR 3.62, 95%CI 1.13–11.58, p = 0.03) and older age (OR 1.05, 95%CI 1–1.11, p = 0.048) were associated with a higher risk of dehydration. Dehydration was significantly associated with an unfavorable outcome at discharge (OR 5.16, 95%CI 1.45–18.25, p = 0.011), but the association was not significant at 3 months (OR 2.95, 95%CI 0.83–10.48, p = 0.095).
Conclusion: Dehydration is a treatable risk factor of a poor functional outcome after stroke that is present in 9% of patients. Females and elders present a higher risk of dehydration.

. 2017; 17: 20.
Published online 2017 Jan 31. doi: 10.1186/s12883-017-0808-3
PMCID: PMC5282628
PMID: 28143595

Elevated blood viscosity is associated with cerebral small vessel disease in patients with acute ischemic stroke



Increased level of blood viscosity, which is one of the major factors that determine blood rheology, has been reported as a risk factor or predictor for cerebrovascular events. We investigated how blood viscosity is associated with acute stroke and chronic radiological manifestations of cerebral small vessel disease, and how blood viscosity changes after stroke.


We prospectively enrolled consecutive patients with acute ischemic stroke. Whole blood viscosities at a low or high shear rate were measured using a scanning capillary tube viscometer, and were referred to as diastolic blood viscosity (DBV) and systolic blood viscosity (SBV), respectively. Correlations between blood viscosity and acute stroke etiology or chronic radiological manifestations of cerebral small vessel disease were investigated. The temporal profiles of blood viscosity at the onset of stroke and follow-up at 1 and 5 weeks were investigated.


Of the 127 patients admitted with acute ischemic stroke, 63 patients were included in the final analyses. DBV at the onset of stroke was significantly higher in small artery occlusion (SAO) stroke than in other stroke subtypes (p = 0.037). DBV showed a significant positive correlation with the number of chronic lacunes (r = 0.274, p = 0.030). The temporal profiles of DBV in SAO stroke showed a transient decrease due to the hydration therapy after 1 week and recurrent elevation at 5 week follow-up (p = 0.009).


Our study suggests that elevated DBV may play a role in the development of acute and chronic manifestations of cerebral small vessel disease. The recurring elevation of DBV in SAO stroke indicates that sufficient hydration and additional therapeutic interventions targeting blood viscosity may be needed in patients with SAO stroke.

Front. Neurol., 20 September 2018 |

Effects of Dehydration on Brain Perfusion and Infarct Core After Acute Middle Cerebral Artery Occlusion in Rats: Evidence From High-Field Magnetic Resonance Imaging

Yuan-Hsiung Tsai1, Jenq-Lin Yang2, I-Neng Lee3, Jen-Tsung Yang4, Leng-Chieh Lin5, Yen-Chu Huang6, Mei-Yu Yeh7, Hsu-Huei Weng1 and Chia-Hao Su2*
  • 1Departments of Diagnostic Radiology, Chang Gung Memorial Hospital, Chiayi, College of Medicine, Chang Gung University, Taoyuan, Taiwan
  • 2Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
  • 3Department of Medical Research, Chang Gung Memorial Hospital, Chiayi, Taiwan
  • 4Department of Neurosurgery Chang Gung Memorial Hospital, Chiayi, College of Medicine, Chang Gung University, Taoyuan, Taiwan
  • 5Department of Emergency Medicine Chang Gung Memorial Hospital, Chiayi, College of Medicine, Chang Gung University, Taoyuan, Taiwan
  • 6Department of Neurology, Chang Gung Memorial Hospital, Chiayi, College of Medicine, Chang Gung University, Taoyuan, Taiwan
  • 7Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan
Background: Dehydration is common among ischemic stroke patients and is associated with early neurological deterioration and poor outcome. This study aimed to test the hypothesis that dehydration status is associated with decreased cerebral perfusion and aggravation of ischemic brain injury.
Methods: Diffusion-weighted imaging and arterial spin labeling perfusion MR imaging were performed on rats with middle cerebral artery occlusion (MCAO) by using a 9.4T MR imaging scanner to measure the volume of infarction and relative cerebral blood flow (rCBF) after infarction. Twenty-five rats were assigned to either a dehydration group or normal hydration group, and dehydration status was achieved by water deprivation for 48 h prior to MCAO.
Results: The volume of the infarction was significantly larger for the dehydration group at the 4th h after MCAO (p = 0.040). The progression in the infarct volume between the 1st and 4th h was also larger in the dehydration group (p = 0.021). The average rCBF values of the contralateral normal hemispheres at the 1st and the 4th h were significantly lower in the dehydration group (p = 0.027 and 0.040, respectively).
Conclusions: Our findings suggested that dehydration status is associated with the progression of infarct volume and decreases in cerebral blood flow during the acute stage of ischemic stroke. This preliminary study provided an imaging clue that more intensive hydration therapies and reperfusion strategies are necessary for the management of acute ischemic stroke patients with dehydration status.

Acute and chronic effects of hydration status on health

Nutrition Reviews, Volume 73, Issue suppl_2, September 2015, Pages 97–109,
18 August 2015


Maintenance of fluid and electrolyte balance is essential to healthy living as dehydration and fluid overload are associated with morbidity and mortality. This review presents the current evidence for the impact of hydration status on health. The Web of Science, MEDLINE, PubMed, and Google Scholar databases were searched using relevant terms. Randomized controlled trials and large cohort studies published during the 20 years preceding February 2014 were selected. Older articles were included if the topic was not covered by more recent work. Studies show an association between hydration status and disease. However, in many cases, there is insufficient or inconsistent evidence to draw firm conclusions. Dehydration has been linked with urological, gastrointestinal, circulatory, and neurological disorders. Fluid overload has been linked with cardiopulmonary disorders, hyponatremia, edema, gastrointestinal dysfunction, and postoperative complications. There is a growing body of evidence that links states of fluid imbalance and disease. However, in some cases, the evidence is largely associative and lacks consistency, and the number of randomized trials is limited.

Here are the top 4 reasons that dehydration has an adverse impact on athletic performance:
  • Reduction in blood volume– Dehydration can cause an increase in blood pressure. This occurs because dehydration reduces blood volume, your body then has to compensate by retaining more sodium in the blood. When the blood becomes more concentrated and thicker it is more difficult to circulate causing your heart to work harder.
  • Decreased sweat rate- Sweat is one of the ways our bodies regulate temperature and is made up of about 95 percent water. If you aren’t taking in enough water, you aren’t able to sweat. When the body cannot effectively regulate temperature you are putting yourself at an increased risk for heat stroke and heat exhaustion.
  • Decreased heat distribution- Dehydration limits cardiovascular and thermoregulatory responses. This leads to an increase in core temperature. For every 1% decrease in body weight as water there in an increase in core temperature of .10 to .40 degrees Celsius.
  • Increased rate of muscle glycogen use- Muscle glycogen concentrations decrease during prolonged exercise or athletic activity. Glycogen serves as a form of energy storage. Depleting glycogen contributes to muscle fatigue.