Thiamine deficiency, or beriberi, refers to the lack of thiamine pyrophosphate, the active form of the vitamin known as thiamine (also spelled thiamin), or vitamin B-1. Thiamine pyrophosphate, the biologically active form of thiamine, acts as a coenzyme in carbohydrate metabolism through the decarboxylation of alpha ketoacids; it also takes part in the formation of glucose by acting as a coenzyme for the transketolase in the pentose monophosphate pathway. Persons may become deficient in thiamine either by not ingesting enough vitamin B-1 through the diet or by excess use, which may occur in hyperthyroidism, pregnancy, lactation, or fever. Prolonged diarrhea may impair the body's ability to absorb vitamin B-1, and severe liver disease impairs its use.Thiamine is a water-soluble vitamin that is absorbed in the jejunum by 2 processes. When the thiamine level in the small intestines is low, an active transport portal is responsible for absorption. When the thiamine concentration is high, a passive mucosal process takes place. Up to 5 mg of thiamine is absorbed through the small intestines. The small intestine is where phosphorylation of thiamine takes place.
The body cannot produce thiamine and can only store up to 30 mg of thiamine in its tissues. Thiamine is mostly concentrated in the skeletal muscles. Other organs that it is found in are the brain, heart, liver, and kidneys. The half-life of thiamine is 9-18 days. It is excreted by the kidney.
Causes
There are two major types of beriberi:
Wet beriberi affects the cardiovascular system.
Dry beriberi and Wernicke-Korsakoff syndrome affect the nervous system.
Beriberi is rare in the United States because most foods are now vitamin-enriched. If you eat a normal, healthy diet you should get enough thiamine. Today, beriberi occurs mostly in patients who abuse alcohol.
Drinking heavily can lead to poor nutrition, and excess alcohol makes it harder for the body to absorb and store thiamine.
A rare condition known as genetic beriberi is inherited (passed down through families). People with genetic beriberi lose the ability to absorb thiamine from foods. This can happen slowly over time and symptoms occur when the person is an adult. However, because doctors may not consider beriberi in non-alcoholics, this diagnosis is often missed.
Beriberi can occur in breast-fed infants when the mother's body is lacking in thiamine. The condition can also affect infants who are fed unusual formulas that don't have enough thiamine.
Getting dialysis and taking high doses of diuretics raise your risk of beriberi.
Symptoms
Symptoms of dry beriberi include:
- Difficulty walking
- Loss of feeling (sensation) in hands and feet
- Loss of muscle function or paralysis of the lower legs
- Mental confusion/speech difficulties
- Pain
- Strange eye movements (nystagmus)
- Tingling
- Vomiting
Symptoms of wet beriberi include:
- Awakening at night short of breath
- Increased heart rate
- Shortness of breath with activity
- Swelling of the lower legs
Exams and Tests
A physical examination may show signs of congestive heart failure, including:
- Difficulty breathing with neck veins that stick out
- Enlarged heart
- Fluid in the lungs
- Rapid heartbeat
- Swelling in both lower legs
A person with late-stage beriberi may be confused or have memory loss and delusions. The person may be less able to sense vibrations.
A neurological exam may show signs of:
- Changes in the walk
- Coordination problems
- Decreased reflexes
- Drooping of the eyelids
The following tests may be done:
- Blood tests to measure the amount of thiamine in the blood
- Urine tests to see if thiamine is passing through the urine
Treatment
The goal of treatment is to replace the thiamine your body is lacking. This is done with thiamine supplements. Thiamine supplements are given through a shot (injection) or taken by mouth.
Other types of vitamins may also be recommended.
Blood tests may be done after you are given thiamine supplements to see how well you are responding to the medicine.
Outlook (Prognosis)
Untreated, beriberi is often deadly. With treatment, symptoms usually improve quickly.
Heart damage is usually reversible, and a full recovery is expected. However, if acute heart failure has already occurred, the outlook is poor.
Nervous system damage is also reversible, if caught early. If it is not caught early, some symptoms (such as memory loss) may remain even with treatment.
If a patient with Wernicke's encephalopathy receives thiamine replacement, language problems, unusual eye movements, and walking difficulties may go away. However, Korsakoff syndrome (or Korsakoff psychosis) tends to develop as Wernicke's symptoms go away.
Possible Complications
- Coma
- Congestive heart failure
- Death
- Psychosis
When to Contact a Medical Professional
Beriberi is extremely rare in the United States. However, if you feel your family's diet is inadequate or poorly balanced, and you or your children have any symptoms of beriberi, call your health care provider.
Prevention
Eating a proper diet that is rich in thiamine and other vitamins will prevent beriberi. Nursing mothers should make sure that their diet contains all vitamins and be sure that infant formulas contain thiamine.
People who drink heavily should try to cut down or quit, and take B vitamins to make sure their body is properly absorbing and storing thiamine.
