Question 3.3

A 52-year-old female was admitted the previous night with an altered level of consciousness that improved rapidly with administration of glucose. She is referred to ICU the following admission with confusion, ataxia and a worsening level of consciousness. Her CT head scan was normal.

The blood sugar level in the morning is 8 mmol/L on a 5% dextrose infusion at 80 ml/hr. Her full blood count from the previous night is available below:


Patient Value

Normal Adult Range


88 g/L*

130 - 175

White Cell Count

7.4 x 10!:1/L

4.0 - 11.0


88 x 10!:1/L*

150 - 450

Mean Cell Volume

110 fl*

80 - 98

Mean Cell Haemoqlobin

30 pq/cell

27 - 34

Mean Cell Haemoglobin Concentration

320 g/L

310 - 360

Prothrombin time

12 sec

12 - 18

Activated partial thromboplastin time

36 sec

32 - 38

a)    What is the likely cause of her confused state?    (20% marks)

b)    What specific treatment would you institute for resolution of her mental status?    (10% marks)

c)    What blood test would support the diagnosis?    (10% marks)

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College answer

  1. Wernickes encephalopathy                                                                                                
  2. Thiamine IV
  3. Red blood cell transketolase activity (reduced)                                                                                                  


This question closely resembles Question 13.3 from the second paper of 2013 and Question 9.2  from the first paper of 2008. Each time, the college accepts "Wernicke's encephalopathy" and "100mg thiamine" as sufficient two-word responses.

The college also asks for a laboratory test. Of course, Wernicke's encephalopathy is a clinical diagnosis.  However, thiamine deficiency is readily diagnosed by the levels of red cell transketolase.   One may test the levels before and after thiamine supplementation. A low transketolase level along with a >25% rise in level following thiamine supplementation is diagnostic of thiamine deficiency.

Of note is the dose of thiamine. Historuically, the college has accepted 100mg IV daily. However, locally we give 300mg IV tds, UpToDate recommends 500mg IV tds, and Cook et al (1998) recommended 1g daily. Obviously there is disagreement about the ideal dose. A Cochrane review (Day et al, 2013) was not able to reac hany sensible conclusions about the dosage, siting methodological problems in the one and only trial which met the inclusion criteria (Ambrose et al, 2001).


Flynn, Alexandra, et al. "Wernicke’s Encephalopathy: Increasing Clinician Awareness of This Serious, Enigmatic, Yet Treatable Disease." The primary care companion for CNS disorders 17.3 (2015).

Thomson, Allan D., and E. Jane Marshall. "The natural history and pathophysiology of Wernicke's encephalopathy and Korsakoff's psychosis." Alcohol and Alcoholism 41.2 (2006): 151-158.

Gussow, Leon. "Myths of toxicology: thiamine before dextrose." Emergency Medicine News 29.4 (2007): 3-11.

Isenberg-Grzeda, Elie, Haley E. Kutner, and Stephen E. Nicolson. "Wernicke-Korsakoff-syndrome: under-recognized and under-treated." Psychosomatics 53.6 (2012): 507-516.\

Watson, A. J. S., et al. "Acute Wernickes encephalopathy precipitated by glucose loading." Irish journal of medical science 150.1 (1981): 301-303.

Kissoon, Niranjan. "Thiamine before glucose to prevent Wernicke encephalopathy: examining the conventional wisdom." JAMA 279.8 (1998): 583.

Day, Ed, et al. "Thiamine for prevention and treatment of Wernicke‐Korsakoff Syndrome in people who abuse alcohol." The Cochrane Library (2013).

Ambrose, Margaret L., Stephen C. Bowden, and Greg Whelan. "Thiamin Treatment and Working Memory Function of Alcohol‐Dependent People: Preliminary Findings." Alcoholism: Clinical and Experimental Research 25.1 (2001): 112-116.

Cook, Christopher CH, Phillip M. Hallwood, and Allan D. Thomson. "B Vitamin deficiency and neuropsychiatric syndromes in alcohol misuse." Alcohol and Alcoholism 33.4 (1998): 317-336.