KARACHI, PAKISTAN. There is evidence that an under-active thyroid gland (hypothyroidism) may be associated with lone atrial fibrillation. One of our early LAF surveys showed that 45% of respondents had a low basal temperature and 40% of these had actually been diagnosed with hypothyroidism. Impaired memory, depression, numbness, and generalized weakness are common symptoms of hypothyroidism. Researchers at the Aga Khan University in Pakistan recently discovered that 40% of 116 patients with an under-active thyroid gland also had a vitamin B12 deficiency – a B12 level below 200 pg/mL. Twenty-four of the 46 patients diagnosed as being deficient received monthly intramuscular vitamin B12 injections and 14 (58%) of them noted a significant improvement in their symptoms. However, among 21 patients with normal B12 levels who also received monthly injections, 40% reported a significant improvement in their symptoms after 6 months of injections – perhaps indicating a significant placebo effect, or the possibility that the currently established lower limit of the reference range for vitamin B12 is too low. The researchers conclude that all hypothyroid patients should be screened for vitamin B12 deficiency and, if necessary, be given B12 injections to normalize their levels.

Jabbar, A, et al. Vitamin B12 deficiency common in primary hypothyroidism. Journal of Pakistan Medical Association, Vol. 58, May 2008, pp. 258-261