More Testing of Vitamin B-12 Deficiency Urged

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By Linda Stahl, The Courier-Journal

The medical community needs to do a better job of detecting vitamin B-12 deficiency, said Florian Thomas, associate professor of neurology at Saint Louis University. "Just this small step would have broad health implications," said Thomas, who said a blood test commonly used to measure B-12 isn't sensitive enough and should be supplemented with another test. B-12 is needed to produce red blood cells and to maintain a healthy nervous system. It is important for every cell and system in the body, including the blood and nervous system. It is essential for formation of myelin, the fatty sheath that surrounds nerves.

To measure B-12, health providers commonly draw blood and send it to a lab for measurement of B-12 values, which are measured in picograms per milliter (pg/ml). Normal is considered 170 to 200 pg/ml, Thomas said. But he and his colleagues at Saint Louis University have studied patients with normal levels of B-12 who nonetheless have B-12 deficiency.

Second test useful Thomas is urging doctors who think their patients lack the vitamin because of symptoms to also test their blood for methylmalonic acid (MMA), a natural compound in the body that increases when B-12 is lacking. He said the cost of such additional testing wouldn't be great, with a regular blood test for B-12 running about $20 and a blood test for MMA running about $40. "The usual way of diagnosing B-12 deficiency may be inadequate because it underestimates the frequency of the problem, which is present in up to 20 percent of the elderly," Thomas said. He said problems brought on by B-12 deficiencies in the elderly would cost only pennies a day to prevent with a B-12 vitamin pill. Other authorities, including authors of the University of California Berkeley Wellness Letter, recommend that doctors check to see if vitamin B-12 is lacking if a patient develops such symptoms as dementia, hallucinations, memory loss and confusion. B-12 deficiency can occur at any age, but is more common in the older population and can mimic other disorders, including Alzheimer's disease, Thomas said.

Risks of low B-12

B-12 deficiency can cause:

  • Impaired memory
  • Dementia
  • Irritability
  • Depression
  • Weakness
  • Pain, numbness or tingling in the hands and feet
  • Lack of coordination

According to the National Institutes of Health, other symptoms and problems associated with B-12 deficiency include: Anemia

  • Fatigue
  • Constipation
  • Loss of appetite
  • Weight loss

In infants, B-12 deficiency can cause failure to thrive, movement disorders, delayed development and a type of anemia.

Daily dose The National Academy of Sciences recommends that adults over 50 get 6 to 12 micrograms of B-12 a day and advises taking supplements or eating foods, such as breakfast cereals, fortified with B-12. Fortified foods release the B-12 more easily than foods in which the vitamin naturally occurs. Thomas sees no harm in taking a higher dosage than recommended in supplement form, saying there is "no fear of overdosing" because the vitamin is water-soluble. Thomas also noted that elderly patients undergoing surgery or dental work where laughing gas, or nitrous oxide, is administered are in special danger if they have undiagnosed B-12 deficiencies. Nitrous oxide can inhibit the use of B-12 by the body when stores of it in the tissues are low. Thomas thinks that surgeries and dental practices that use laughing gas should routinely test patients in advance for B-12 deficiencies. Otherwise, within a week a person with low B-12 stores who gets laughing gas might exhibit symptoms such as confusion and memory loss.

Who needs tests Thomas urged that patients be rigorously tested before surgery to see if they have low B-12 stores and tested after age 65 every two years. Thomas and Saint Louis University researchers Dr. Chitharanjan Rao and Dr. John Selhorst also have found that it can be difficult to distinguish multiple sclerosis from B-12 deficiency. Some medical personnel, young adults and teenagers abuse nitrous oxide, buying it from baking supply stores or using the gas contained in whipped-cream dispensers. Nitrous oxide abuse resulting in B-12 deficiency should be considered in young adults with unusual neurological conditions, Thomas said.

Copyright 2004 The Courier-Journal.

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