Vitamin B12 deficiency and autonomic dysfunction

VITAMIN B12 DEFICIENCY AND AUTONOMICDYSFUNCTIONDR. GÜLNİHAL TUFANSUMMARYThere are a few studies suggesting that vitamin B12 deficiency causes bothsympathetic and parasympathetic dysfunction. The researches studying existenceof autonomic dysfunction and response to the therapy in vitamin B12 deficiencyboth were a few in number and brought to contradictory results. The patients whohave vitamin B12 deficiency without hematological disorders can be frequentlyseen. It was also put forward that the neurological involvement could be moresevere in these patients. The aims of our study are investigation of autonomicdysfunction in the patients with vitamin B12 deficiency using cardiac autonomicdysfunction tests, evaluation of response to therapy in patients with autonomicdysfunction, and the association between autonomic dysfunction andhematological parameters.Twenty patients (18-70 years old) who were recently diagnosed as vitaminB12 deficient without any associated disease and not treated with vitamin B12before were enrolled in the study. Twenty healthy volunteers were included in thecontrol group. The routine biochemical laboratory tests, complete blood counts,serum vitamin B12 levels, and cardiac autonomic dysfunction tests wereperformed before and 4 months after the vitamin B12 treatment. The symptomswhich could be consistent with autonomic dysfunction were asked and recorded.The difference between hemoglobin, hematocrite, leukocyte and plateletlevels of the patients and control group was not significant (p> 0.05). The majorindications for measuring serum vitamin B12 levels were anemia, fatigue andparaesthesia in our patient group. In the patient group, fatigue, paraesthesia andextremity cramps were the main symptoms which could be seen with autonomicdysfunction. Before the treatment of vitamin B12 deficiency, ten patients (% 50)were found to have overall parasympathetic dysfunction, nine patients (% 45)were found to have limited parasympathetic dysfunction. The remainder onepatient (% 5) had normal cardiac autonomic dysunction test results. Only onepatient (% 5) had orthostatic hypotension, evidence of sympathetic dysfunction. Inour study with vitamin B12 treatment, the initial overt abnormal heart rate testresults improved as normal or limited abnormal and the initial limited abnormalheart rate results improved as normal.In conclusion, vitamin B12 deficiency may result in autonomicdysfunction without causing anemia and autonomic dysfunction can be improvedwith vitamin B12 treatment. Further investigations are required for evaluation ofthe association between severity and duration of vitamin B12 deficiency andautonomic dysfunction and the duration of expected time for improvement withthe therapy.