Thiamine deficiency may manifest in a number of ways:
- Infantile beriberi – Secondary to thiamine-deficient mothers exclusively breastfeeding or due to the absence of thiamine in formula for exclusively formula-fed infants (exceedingly uncommon).
- High mortality with rapid progression to death.
- Infants usually appear normal at first; constipation and vomiting progress to the development of dyspnea, peripheral edema, and oliguria.
- Pure cardiologic form (pernicious form) – Infants develop cyanosis progressing to acute cardiac insufficiency and death within hours. Seen in ages 1-3 months.
- Aphonic form – Milder form with loss of voice due to paresis or paralysis of vocal cord. Seen in ages 4-6 months.
- Pseudomeningitis form – Seen in older infants (ages 7-9 months) presenting with neck stiffness, vomiting, diaphoresis, and seizure. Can be mistaken for bacterial meningitis.
- Adult beriberi, dry; also known as thiamine deficiency with peripheral neuropathy – Characterized by symmetrical distal extremity peripheral neuropathy. These patients have reduced deep tendon reflexes, progressive weakness, and muscle wasting, often with increased susceptibility to infection.
- Adult beriberi, wet; also known as thiamine deficiency with cardiopathy – Characterized by dilated cardiomyopathy with high output heart failure, peripheral edema, and pulmonary edema.
- Shoshin beriberi – Fulminant wet beriberi characterized by cardiogenic shock, lactic acidosis, and multiple organ failure.
- Thiamine deficiency with cardiopathy and peripheral neuropathy – It should be noted that many cases of thiamine deficiency demonstrate a mixture of dry (neuritic) and wet (cardiac) types.
- Leigh syndrome – A mitochondrial disorder of progressive subacute necrotizing encephalomyopathy of infancy associated with thiamine deficiency.
Thiamine deficiency may also lead to alcohol amnestic disorder. Wernicke encephalopathy is a triad of nystagmus, ophthalmoplegia, and ataxia with associated confusion. It is often found in people with alcohol use disorder who have chronic thiamine deficiency. Thiamine deficiency may also play a role in tropical ataxic neuropathy, a condition endemic to Nigeria that is characterized by polyneuropathy, gait ataxia, bilateral optic atrophy, and deafness.
Thiamine deficiency is intrinsically linked to global poverty, food insecurity, and malnutrition. It is endemic to some areas in Southeast Asia, Africa, South America, and the Caribbean. Some raw and fermented fish sauces commonly consumed in Asia, as well as vegetables and roasted insects consumed in some Asian and African diets, contain the enzyme thiaminase, which degrades thiamine and further leads to deficiency. Infants with malnourished mothers in endemic regions have the highest risk of developing thiamine deficiency.
It is less common in developed countries where flour and infant formula are often fortified with thiamine. In the United States, alcohol use disorder is the most common cause of thiamine deficiency; however, it is also associated with HIV infection, long-term parenteral nutrition, hyperemesis gravidarum, anorexia nervosa, and bariatric surgery.