Low B12 Linked to Orthostatic Tachycardia in Adolescents

Laurie Barclay, MD

December 23, 2013

Vitamin B12 deficiency in adolescents may cause sympathetic nervous system baroreceptor dysfunction, leading to postural orthostatic tachycardia syndrome (POTS), according to a clinical study published online December 23 in Pediatrics.

"Studies have shown dysfunction in the baroreflex mechanism and the autonomic nervous system, particularly in the sympathetic nervous system, in the pathophysiology of chronic fatigue syndrome, [POTS], and syncope," write Taliha Öner, MD, from the Division of Cardiology, Department of Pediatrics, Dr. Behçet Uz Children's Hospital in Alsancak, Izmir, Turkey, and colleagues.

"Vitamin B12 is involved in the production of adrenaline from noradrenaline. It is the cofactor involved in catecholamine degradation and plays a role in myelin synthesis," the authors add.

Therefore, the study goal was to evaluate the association between vitamin B12 levels and POTS during adolescence, an age during which accelerated myelin synthesis increases the demand for vitamin B12. The investigators compared 125 patients who presented with short-term loss of consciousness and were diagnosed with vasovagal syncope with 50 control participants. Mean age was 11.1 ± 2.3 years and 10.94 ± 2.5 years, respectively, and 60% of each group was female. Syncope was more common in girls older than 10 years.

Prospective measurements included serum vitamin B12, folic acid, and ferritin levels, as well as other tests. Vitamin B12 deficiency was defined as serum level lower than 300 pg/mL.

Low B12 More Common in Patients

A higher percentage of participants in the patient group had low vitamin B12 levels compared with the control group, (47.2% vs 18%; P < .001). However, hemoglobin, hematocrit, mean corpuscular volume, folic acid, and ferritin values did not differ between the groups.

Not all patients with low vitamin B12 levels developed orthostatic hypotension. A total of 47.2% of patients had vitamin B12 deficiency, but the orthostatic hypotension rate in that group was 12.6%. Of those in the patient group, 28.8% had a positive tilt test, and POTS was found in 28%. Low vitamin B12 levels were seen in 62.8% of the patients with POTS.

"Vitamin B12 deficiency in patients with POTS may lead to sympathetic nervous system baroreceptor dysfunction," the authors write.

"Vitamin B12 deficiency is associated with [POTS] in adolescence," they add.

Limitations of this study include those inherent in tilt table measurement of orthostatic changes.

"Vitamin B12 deficiency is known to be more common among the elderly, although there is a currently increasing prevalence among adolescents worldwide," the authors write. "This is due to the increased need associated with accelerated development, decreased intake related to inadequate diet (vegetarian diet, obesity), and the side effects of medications (metformin used in the treatment of obesity, oral contraceptives, and antireflux medications such as proton pump inhibitors)," they conclude.

This study received no external funding. The authors have disclosed no relevant financial relationships.

Pediatrics. Published online December 23, 2013. Abstract

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