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Riboflavin (vitamin B2) is involved in carbohydrate metabolism as an essential coenzyme in many oxidation-reduction reactions. Riboflavin is essentially nontoxic.
Riboflavin
Deficiency
Riboflavin
deficiency usually occurs with other B-vitamin deficiencies. Symptoms
and signs include sore throat, lesions of the lips and mucosa of
the mouth, glossitis, conjunctivitis, seborrheic dermatitis, and
normochromic-normocytic anemia. Diagnosis is usually clinical. Treatment
consists of oral or, if needed, IM riboflavin.
Primary riboflavin deficiency results from inadequate intake of fortified cereals, milk, and other animal products. The most common causes of secondary deficiency are chronic diarrhea, malabsorption syndromes, liver disorders, hemodialysis, peritoneal dialysis, long-term use of barbiturates, and chronic alcoholism.
Symptoms
and Signs
The most common signs are pallor and maceration of the mucosa at the angles of the mouth (angular stomatitis) and vermilion surfaces of the lips (cheilosis), eventually replaced by superficial linear fissures. The fissures can become infected with Candida
albicans, causing grayish white lesions (perlèche). The tongue may appear magenta. Seborrheic dermatitis develops, usually affecting the nasolabial folds, ears, eyelids, and scrotum or labia majora. These areas become red, scaly, and greasy.
Rarely, neovascularization and keratitis of the cornea occur, causing lacrimation and photophobia.
Diagnosis
and Treatment
The lesions characteristic of riboflavin deficiency are nonspecific. Riboflavin deficiency should be suspected if characteristic signs develop in a patient with other B vitamin deficiencies. Diagnosis can be confirmed by a therapeutic trial or laboratory testing, usually by measuring urinary excretion of riboflavin.
Riboflavin 5 to 10 mg/day po is given until recovery. Other water-soluble vitamins should also be given.
Last full review/revision April 2007 by Larry E. Johnson, MD, PhD
Content last modified April 2007
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