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Pronunciations atrophy edema encephalopathy Wernicke's encephalopathy Wernicke-Korsakoff syndrome

Thiamin (vitamin B₁) is widely available in the diet. It is essential for the metabolism of carbohydrates (to produce energy) and for normal nerve and heart function. Thiamin is not toxic.

Thiamin Deficiency

• A diet consisting mainly of white flour, white sugar, and other highly processed carbohydrates can cause thiamin deficiency.
• At first, people have vague symptoms such as fatigue and irritability, but a severe deficiency (beriberi) can affect the nerves, muscles, heart, and brain.
• The diagnosis is based on symptoms.
• Thiamin supplements, usually taken by mouth, can correct the deficiency.

Thiamin deficiency often occurs with other B vitamin deficiencies. It may result from a deficiency in the diet. People whose diet consists mainly of highly processed carbohydrates (such as polished white rice, white flour, and white sugar) are at risk of thiamin deficiency. Polishing rice removes almost all of the vitamins. Alcoholics, who often substitute alcohol for food and thus do not consume enough thiamin, are at high risk of developing this deficiency.

Thiamin deficiency may also result from disorders or conditions that increase the body's need for thiamin. Examples are thyroid disorders, pregnancy, breastfeeding, and fever. Liver disorders may interfere with the processing (metabolism) of the vitamin.

Symptoms

Early symptoms are vague. They include fatigue, irritability, poor memory, loss of appetite, sleep disturbances, abdominal discomfort, and weight loss. Eventually, a severe thiamin deficiency (beriberi) may develop, characterized by nerve, heart, and brain abnormalities. Different forms of beriberi cause different symptoms.

Dry Beriberi: Nerve and muscle abnormalities develop. Symptoms include a prickling (pins-and-needles) sensation in the toes, a burning sensation in the feet that is particularly severe at night, and leg cramps and pain. Muscles may become weak and waste away (atrophy).

Wet Beriberi: Heart abnormalities develop. The heart pumps more blood and beats faster. Blood vessels widen (dilate), making the skin warm and moist. Because the heart cannot continue to work at this level, heart failure eventually develops. As a result, fluid accumulates in the legs (as edema) and in the lungs (as congestion), and blood pressure may fall, leading to shock and death.

Brain Abnormalities: Thiamin deficiency causes brain abnormalities primarily in alcoholics. Brain abnormalities may first cause symptoms after an alcoholic binge by suddenly worsening a long-standing deficiency. Brain abnormalities can also cause symptoms after an alcoholic is given carbohydrates intravenously. Symptoms occur because these extra carbohydrates further increase thiamin requirements. These brain abnormalities are called the Wernicke-Korsakoff syndrome (see Brain Dysfunction: Wernicke-Korsakoff Syndrome), which has two parts:

• Wernicke's encephalopathy causes confusion, difficulty walking, and eye problems, including involuntary eye movements (nystagmus) and partial paralysis of the eyes. If Wernicke's encephalopathy is not promptly treated, symptoms may worsen, resulting in coma and even death.
• Korsakoff's psychosis causes memory loss for recent events, confusion, and a tendency to make up facts to fill in gaps in memories (confabulation).

Infantile Beriberi: This form occurs in infants (usually by age 3 to 4 wk) who are breastfed by a mother who has a thiamin deficiency. In these infants, heart failure may occur suddenly. They may lose their voice (aphonia) to some degree, and they may not have certain reflexes.

Diagnosis and Treatment

The diagnosis is based on symptoms. Tests to confirm the diagnosis are not readily available. Blood tests to measure electrolyte levels are usually done to exclude other possible causes. The diagnosis is confirmed if thiamin supplements relieve symptoms.

All forms of the deficiency are treated with thiamin supplements. They are usually given by mouth. They are given intravenously if symptoms are severe.

Wernicke-Korsakoff syndrome, a medical emergency, is treated with high doses of thiamin given intravenously or by injection into a muscle (intramuscularly) for several days. Use of alcohol should be stopped. When people who may be alcoholics must be fed intravenously, they are given thiamin supplements first to prevent the syndrome from developing or worsening.

With treatment, most people recover completely. In some people with Wernicke-Korsakoff syndrome, some brain damage is permanent. Symptoms of beriberi may recur years after apparent recovery.

Last full review/revision August 2007 by Larry E. Johnson, MD, PhD