Acquired biotin deficiency

It is important to note that normal plasma biotinidase activity does not exclude that the patient has another cause of multiple carboxylase deficiency (i.e. HCS deficiency or acquired biotin deficiency) [2, 30]. 

Acquired biotin deficiency is extremely rare but may occur in special conditions such as long-term parenteral nutrition without biotin supplementation, short bowel syndrome and after excessive intake of raw egg white, which contains the potent bio-tin-binding protein avidin. The main symptoms are alopecia and skin abnormalities which resolve after administration of biotin [2, 30]. 

Urinary organic acid analysis is useful for differentiating isolated carboxylase deficiencies from the biotin-responsive multiple carboxylase deficiencies. P-Hydroxyisovalerate is the most common urinary metabolite observed in isolated P-methylcrotonyl-CoA carboxylase deficiency, biotinidase deficiency, biotin holo-carboxylase synthetase deficiency, and acquired biotin deficiency. In addition to P-hydroxy-isovalerate, elevated concentrations of urinary lactate, methylcitrate, and P-hydroxypropionate are indicative of multiple carboxylase deficiency. 

Daily doses up to 200 mg orally and up to 20 mg intravenously have been given to treat biotin-responsive inborn errors of metabolism and acquired biotin deficiency. Toxicity has not been reported. 

Because daily requirements are very low (around 100 p,g for humans) and because biotin is present in many foodstuffs, acquired deficiency is rare but can be induced in animals by feeding them with raw egg whites, which contain avidin, a glycoprotein that has a very high affinity for biotin (see below). Cases of spontaneous biotin deficiency in humans were not detected before 1976, but since then several cases have been diagnosed. Two inherited disorders have been described holo-carboxylase synthase deficiency and biotinidase deficiency (50,51). Both lead to multiple carboxylase deficiency that is deficiency in the four biotin-dependent carboxylases found in animals. The clinical symptoms (cutaneous and neurological) can be eliminated by biotin absorption (up to 10 mg/day). In HCS deficiency, a lower affinity of the altered HCS for biotin impairs the formation of holocarbox-ylases. In biotinidase deficiency the patient is unable to recover biotin from bio-cytin, which is then excreted. 

Baumgartner ER, Suormala T (1997) Multiple carboxylase deficiency inherited and acquired disorders of biotin metabolism. Int J Vitam Nutr Res 67 377-384... 

---

See also in sourсe #XX -- [ ]

---