Clinical beriberi

Beriberi is caused by a deficiency of thiamin (also called thiamine, aneurin(e), and vitamin Bj). Classic overt thiamin deficiency causes cardiovascular, cerebral, and peripheral neurological impairment and lactic acidosis. The disease emerged in epidemic proportions at the end of the nineteenth century in Asian and Southeast Asian countries. Its appearance coincided with the introduction of the roller mills that enabled white rice to be produced at a price that poor people could afford. Unfortunately, milled rice is particularly poor in thiamin thus, for people for whom food was almost entirely rice, there was a high risk of deficiency and mortality from beriberi. Outbreaks of acute cardiac beriberi still occur, but usually among people who live under restricted conditions. The major concern today is subclinical deficiencies in patients with trauma or among the elderly. There is also a particular form of clinical beriberi that occurs in patients who abuse alcohol, known as the Wer-nicke-Korsakoff syndrome. Subclinical deficiency may be revealed by reduced blood and urinary thiamin levels, elevated blood pyruvate/lactate concentrations and a-ketoglutarate activity, and decreased erythrocyte transketolase (ETKL) activity. Currently, the in vitro stimulation of ETKL activity by thiamin diphosphate (TDP) is the most useful functional test of thiamin status where an acute deficiency state may have occurred. The stimulation is measured as the TDP effect. 

Diseases and disorders resulting from a deficiency of thiamine include beriben, opisthotonos (in birds), polyneuritis, hyperesthesia, bradycardia, and edema. Rather than a specific disease, beriberi may be described as a clinical state resulting from a thiamine deficiency. In body cells, thiamine pyrophosphate is required for removing carbon dioxide from various substances, including pyruvic acid. Actually, this is accomplished by a decarboxylase of which thiamine pyrophosphate is a part. Where... 

Beriberi (infantile and adult) and Wernicke s encephalopathy (WE) are clinical manifestations attributed to thiamine deficiency. Beriberi is characterized by peripheral neuropathy including sensory, motor, and reflex functions affecting the distal segments of limbs more severely than proximal ones (TanPhaichitr, 1985). WE is a metabolic disease due to thiamine deficiency and is characterized by lesions in the thalamus, hypothalamus (including mammillary nuclei), and cerebellum (Victor et al., 1971 Harper and Butterworth, 1997). 

One could more readily explain the clinical signs of scurvy on the basis of the function of vitamin C in collagen formation, than one could explain the development of wet beriberi for thiamine, or of cheilosis for riboflavin function. For instance, why shouldn t riboflavin cause beriberi, and thiamine cause cheilosis—rather than the reverse We cannot explain this. The situation exemplifies that we often cannot explain the clinical findings on the basis of what is known about the biochemical function of the vitamin. There is still much more to be learned about vitamin nutrition, and this is exemplified by vitamin C. 

At present, the important clinical indication areas for therapy with thiamine are the beriberi of alcoholics and Wernicke s encephalopathy (Korner and Vollm 1976). In both cases, therapy is started with daily doses of at least 50-100 mg (in severe cases up to 200 mg) thiamine administered parenterally. Therapy is then continued with oral doses of 100-300 mg daily. Neuritis accompanying pregnancy responds particularly well to vitamin therapy. In some severe disorders of the intermediate metabolism (e.g., diabetic acidosis, severe hepatic malfunction), the necessary phosphorylation of thiamine in the organism is no longer ensured. Thiamine has, therefore, to be administered directly in its active form, thiamine pyrophosphate (TPP, cocarboxylase). Instances of toxicity of thiamine have been reported, primarily showing effects on the cardiovascular and nervous systems (Un-NA 1972 DiPalma and Ritchie 1977). 

A variety of clinical forms of beriberi have been described, but the disease is usually classified as wet or dry. The wet form is usually a combination of edema (probably a consequence of congestive heart failure) and polyneuritis [62-64]. 

Symptoms of overt beriberi are usually abrupt with presentation of left ventricular cardiac and peripheral vascular failure yielding water retention due to stimulation of the renin-angiotensin-aldosterone axis by hypovolemia, as well as striated and smooth muscles weakness in the wet form of the disease. At this stage of the disease, the clinical diagnosis is usually apparent but outcome of the supplementary treatment with thiamine may be poor, due to irreversible alterations in muscles and the central nervous system (CNS). 

Beriberi. Clinical manifestations of thiamine deficits in the form of vascular and neurological disturbances including motor impairment, sensory and reflex functions, mental confusion, oedema and cardiomyopathy. Beriberi can be fatal if thiamine is not supplied. 

Clinical Effects of Thiamin Deficiency. If a deficiency of thiamin is not corrected (if thiamin is not present in sufficient amounts to provide the key energizing coenzyme factor in the cells), the clinical effects will be reflected in the gastrointestinal system, the nervous system, and the cardiovascular system. Severe thiamin deficiency of long duration will culminate in beriberi, the symptoms of which are polyneuritis (inflammation of the nerves), emaciation and/or edema, and disturbances of heart function. 

Clinical signs adapted from several studies. Investigators were impressed by the rapid degree of debility induced by the specific withdrawal of thiamin from the diet. In one group (150pg/day for 75days, four female mental patients), the authors reported that the condition more closely resembled neurasthenia than beriberi and noted that oedema, cardiac dilation, and peripheral pain characteristic of classic beriberi were all absent (reported by Carpenter, 2002). 

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