Subclinical deficiency state

Beriberi occurs whenever thiamine intake is less than 0.4 mg/d for an extended period of time. It occurs where polished rice is a dietary staple, and, in Western society, in poor and elderly populations and alcoholics. Beriberi has wet, dry, and cardiac types, and an individual may have more than one type. Wet refers to pleural and peritoneal effusions and edema dry refers to polyneuropathy without effusions. Cardiomyopathy is the principal feature of the cardiac type. An infantile form occurs in breast-fed infants, usually 2-5 months of age, nursing from thiamine-deficient mothers. The symptoms of beriberi remit completely upon thiamine supplementation. A subclinical deficiency of thiamine occurs in hospital patients and the elderly. Deficiency of thiamine and other vitamins may contribute to a generally reduced state of health in these populations. 

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. 

Ascorbic acid, a water-soluble vitamin (1(X) to 250 mg p.o. daily), is indicated in the treatment of frank and subclinical scurvy in extensive bums, delayed fracture or wound healing, postoperative wound healing severe febrile or chronic disease states and in prevention of ascorbic acid deficiency in those with poor nutritional habits or increased requirements. In addition, ascorbic acid has been used for potentiation of meth-enamine in urine acidification and as an adjunctive therapy in the treatment of idiopathic methemoglobinemia. 

The recommended riboflavin requirements for humans vary with respect to sex, age, and physiological state (such is the case during pregnancy and lactation). Normal adults need to consume between 0.9 and 1.6 mg of this vitamin on a daily basis since the human body does not have deposits of riboflavin and an excess of vitamin intake is eliminated in urine (Institute of Medicine 1998). Although present in a wide variety of foods, riboflavin deficiency (ariboflavinosis) still occurs in both developing and industrialized countries (O Brien et al. 2001 Blanck et al. 2002). Even though severe cases of ariboflavinosis are not common in most societies, subclinical manifestations are frequent and these are only detectable by measuring the blood vitamin concentrations. 

---