140
CASE FILES: BIOCHEMISTRY
A N SW E R S TO C A SE 15: T H IA M IN E D E F IC IE N C Y
Summary:
A 59-year-old male with history of heavy alcohol use presents with
mental confusion, ataxia, and ophthalmoplegia.
Most likely diagnosis: Wernicke-Korsakoff syndrome (thiamine
deficiency) often associated with chronic alcoholics.
Importance of thiamine: An important water-soluble vitamin used as
a cofactor in enzymatic reactions involving the transfer of an aldehyde
group. Without thiamine, individuals can develop dementia, macrocytic
anemia (folate deficiency), gastritis, peptic ulcer disease, liver disease,
depression, nutritional deficiencies, cardiomyopathy, and pancreatitis.
C L IN IC A L C O R R E L A T IO N
Thiamine, also known as vitamin B1, is fairly ubiquitous. Thiamine deficiency
is uncommon except in alcoholics as a result of nutritional deficiencies and
malabsorption. The classic clinical triad of dementia, ataxia (difficulty with
walking), and eye findings may be seen, but more commonly, only forgetful-
ness is noted. Sometimes, thiamine deficiency can lead to vague symptoms
such as leg numbness or tingling. Because thiamine is water soluble, it can be
added to intravenous fluids and administered in that way. Other manifestations
include beri beri, which is cardiac involvement leading to a high cardiac out-
put, and vasodilation. Affected patients often feel warm and flushed, and they
can have heart failure.
A PPR O A C H TO T H IA M IN E PY R O PH O SPH A T E
O bjectives
1.
Know about the role of thiamine pyrophosphate (TPP) in pyruvate
dehydrogenase.
2.
Understand the role of TPP in a-ketoglutarate dehydrogenase and the
role of TPP in transketolase in pentose phosphate pathway.
3.
Be familiar with how thiamine deficiency results in decreased energy
generation and how it results in decreased ribose and NADPH
production.
D efinitions
Carbanion: A carbon within a molecule that has a negative charge because
of the removal of a proton (hydrogen ion).
Decarboxylation: The process of removing a carboxyl group (-COOH)
from a molecule. Frequently this is achieved by oxidizing the compound
in a process known as oxidative decarboxylation.
previous page 154 Case Files   Biochemistry read online next page 156 Case Files   Biochemistry read online Home Toggle text on/off