Biotin Deficiency

Excerpt

Biotin (vitamin B7) is a water-soluble B-complex vitamin that plays a vital role in cellular metabolism. This vitamin is an essential cofactor for several carboxylase enzymes involved in the metabolism of fatty acids, amino acids, and glucose. These include acetyl-coenzyme A (CoA) carboxylase, propionyl-CoA carboxylase, β-methylcrotonyl-CoA carboxylase, and pyruvate carboxylase, each of which catalyzes reactions necessary for maintaining metabolic homeostasis.

Biotin deficiency is rare in the general population due to its presence in various dietary sources, including eggs, nuts, legumes, and certain vegetables, and its endogenous synthesis by intestinal microbiota. However, deficiency may occur in specific at-risk groups, including individuals receiving long-term antibiotic therapy (which disrupts intestinal flora), chronic anticonvulsant therapy (which alters biotin metabolism), or total parenteral nutrition without adequate supplementation.

Clinically, biotin deficiency develops gradually and initially presents with nonspecific symptoms such as fatigue, hair thinning or alopecia, and eczematous skin rashes. If left untreated, the deficiency may progress to neurologic manifestations, including paresthesias, peripheral neuropathy, myalgias, and, in severe cases, cognitive impairment or seizures. Due to these findings' subtle and variable nature, diagnosis is often delayed or overlooked.

While biotin supplements are widely marketed for hair, skin, and nail health, limited clinical evidence supports their use in individuals without a documented deficiency. Moreover, high-dose biotin supplementation has been shown to interfere with immunoassays, particularly those measuring thyroid hormones and cardiac biomarkers (eg, troponins), which may result in false-positive or false-negative results and lead to inappropriate diagnostic or therapeutic decisions.