Wernicke-Korsakoff Syndrome: This condition is directly associated with thiamine deficiency, particularly in individuals with alcohol use disorder. It presents with symptoms such as confusion, ataxia, and ophthalmoplegia, making it a prime suspect when considering the effects of low thiamine levels.

Beriberi: A disease caused by thiamine deficiency, characterized by neurological and cardiovascular symptoms. It can present in different forms, including wet beriberi (with edema) and dry beriberi (without edema).
Alcoholic Neuropathy: While not exclusively caused by thiamine deficiency, alcohol misuse can lead to thiamine deficiency, which in turn can exacerbate or contribute to the development of alcoholic neuropathy, characterized by nerve damage.

Pellagra: Caused by niacin deficiency, pellagra can sometimes be confused with thiamine deficiency due to overlapping symptoms such as dermatitis, diarrhea, dementia, and potentially death if left untreated. Although it's a different vitamin deficiency, the clinical presentation can sometimes lead to consideration of thiamine deficiency.
Hypothyroidism: While not directly related to thiamine levels, hypothyroidism can cause fatigue, muscle weakness, and neurological symptoms that might be considered in the differential diagnosis of thiamine deficiency due to the broad range of symptoms that can be presented.

Leigh Syndrome: A rare genetic disorder that affects the central nervous system and can lead to thiamine deficiency among other metabolic issues. It's characterized by progressive loss of mental and movement abilities.
Thiamine-responsive megaloblastic anemia syndrome (TRMA): A rare genetic disorder that responds to thiamine treatment, characterized by megaloblastic anemia, diabetes mellitus, and sensorineural deafness. It's an important consideration in cases where thiamine deficiency is suspected and other causes have been ruled out.