Sources, Functions, and Effects of Vitamins
Plasma tocopherol levels vary with total plasma lipid levels. Normally, the plasma alpha-tocopherol level is 5 to 20 mcg/mL (11.6 to 46.4 mcmol/L).
1).
(See also Overview of Vitamins.)
Reference
1. Klein EA, Thompson IM Jr, Tangen CM, et alSeleniumJAMA 306(14):1549-56, 2011. doi: 10.1001/jama.2011.1437
In countries with low rates of food insecurity, the most common causes are
Disorders that cause fat malabsorption, including abetalipoproteinemia (Bassen-Kornzweig syndrome, due to genetic absence of apolipoprotein B), chronic cholestatic hepatobiliary disease, pancreatitis, short bowel syndrome, and cystic fibrosis
retinopathy of prematurity (also called retrolental fibroplasia) in premature infants and to some cases of intraventricular and subependymal hemorrhage in neonates. Affected premature neonates have muscle weakness.
In children, chronic cholestatic hepatobiliary disease or cystic fibrosis causes neurologic deficits, including spinocerebellar ataxia with loss of deep tendon reflexes, truncal and limb ataxia, loss of vibration and position senses, ophthalmoplegia, muscle weakness, ptosis, and dysarthria.
Low alpha-tocopherol level or low ratio of serum alpha-tocopherol to serum lipids
< 5 mcg/mL (<< 0.8 mg/g total lipid) is the most accurate indicator in adults with hyperlipidemia.
In children and adults with abetalipoproteinemia, serum alpha-tocopherol levels are usually undetectable.
Supplemental alpha-tocopherol or mixed tocopherols (alpha-, beta-, and gamma-tocopherols)
If malabsorption causes clinically evident deficiency, alpha-tocopherol 15 to 25 mg/kg orally once a day should be given. Or mixed tocopherols (200 IU) can be given. However, larger doses of alpha-tocopherol given by injection are required to treat neuropathy during its early stages or to overcome the defect of absorption and transport in abetalipoproteinemia.
Key Points
The deficiency causes mainly mild hemolytic anemia and nonspecific neurologic deficits.
In patients with inadequate intake or a predisposing condition plus compatible findings, measure the tocopherol level to confirm the diagnosis.
Treat with supplemental tocopherol.