The continuous growth of hair makes it a prime site for showing alterations in the body's general metabolism. The thinning and the shifting of hair into telogen by hormonal deficiency (eg, thyroid) or by protein-calorie malnutrition have been documented previously.
Less common, but no less important, are metabolic disorders associated with distinctive structural abnormalities of the hair. Menkes' syndrome, an X-linked disorder with abnormalities of copper storage and transport, is associated with thin, highly twisted hairs (pili torti). Arginosuccinicaciduria, an autosomal recessive disorder, is associated with a deficiency of an essential enzyme of the urea cycle, ammonia intoxication, and decreased growth. The hairs are thin and show the characteristic changes of trichorrhexis nodosa.
More recently, two vitamin disorders, one of biotin metabolism and one of vitamin D metabolism, have been associated with alopecia, and interest in the role of vitamins in hair growth has been reawakened.
A biotin-responsive form of
Goldsmith LA. Vitamins and Alopecia. Arch Dermatol. 1980;116(10):1135–1136. doi:10.1001/archderm.1980.01640340045013