Methylmalonic acid and homocysteine assessment in the detection of vitamin B12 deficiency in patients with bilateral visual loss

Neurological symptoms of vitamin B12 deficiency: analysis of pediatric patients

Vitamin B12 is one of the essential vitamins that affect various systems in the body, including the central nervous system. Vitamin B12 plays an important part in the metabolism of the nervous system, although its exact role under pathological conditions is not fully understood. The purpose of this study was to emphasize the importance of early diagnosis of vitamin B12 deficiency in the light of the characteristics of the patients enrolled. This retrospective, clinical study included 38 children with neurological symptoms of vitamin B12 deficiency. Records of 38 patients referred to a single center of the university hospital outpatient child neurology clinic due to neurological symptoms of vitamin B12 deficiency between February 2012 and December 2013 were evaluated retrospectively. Patients aged 0-18 years with symptoms including syncope, dizziness, convulsion, hypotonia, developmental retardation, tremor, ataxia, tingling sensations and paresthesia, blurring of vision, fatigue and concentration difficulty caused by vitamin B12 deficiency were included in the study. Patient neurological findings included syncope (n=6), dizziness (n=4), hypotonia (n=9), inability to sit or walk without support, or gait ataxia (n=2), convulsion (n=4), hand tremor (n=1), tingling sensations and paresthesia (n=3), vision blurring (n=1), fatigue and concentration difficulty (n=8). All patients with neurological symptoms of vitamin B12 deficiency recovered within one month after vitamin B12 supplementation. In conclusion, clinical characteristics of vitamin B12 deficiency are broad and nonspecific and may not be associated with anemia and increased mean corpuscular volume. Since different clinical characteristics can be seen without anemia, awareness and cautious approach are essential in order to avoid severe clinical disease, especially in children from underdeveloped countries.

Treatment and Outcomes in Nutritional Optic Neuropathy

PURPOSE OF REVIEW

Nutritional optic neuropathy is a potential cause of severe visual loss; however, appropriate and timely management can result in excellent visual outcomes. The purpose of this review is to outline our current understanding of the treatment and outcomes for nutritional optic neuropathy.

RECENT FINDINGS

Current understanding of nutritional optic neuropathy has been greatly aided by some well-reported and investigated epidemics of the condition, most notably the Cuban epidemic optic neuropathy of the early 1990s. More recently, there is an emerging literature surrounding nutritional deficiencies that can occur in patients who have undergone bariatric surgery. There also continues to be a stream of case reports in the literature that add to our understanding. Nutritional optic neuropathy has a great deal of overlap with toxic optic neuropathies and hereditary optic neuropathies and should not be thought of in isolation from these conditions. The mainstay of treatment for nutritional optic neuropathy involves identifying and replacing deficient nutrients as well as identifying and eliminating contributory toxins. It is also important to identify contributory genetic factors and to consider the broader social, economic and societal factors which may contribute.

Functional cobalamin (vitamin B12) deficiency: role of advanced age and disorders associated with increased oxidative stress

BACKGROUND/OBJECTIVE

Functional cobalamin (Cbl; vitamin B12) deficiency (that is, high levels of the Cbl-dependent metabolites, methylmalonic acid (MMA) and homocysteine (HCys), despite normal serum Cbl values) is common in the elderly and is associated with neurocognitive abnormalities, but its cause is unknown. As only reduced Cbls are metabolically active, the possibility that functional Cbl deficiency is associated with disorders having biomarkers indicative of increased oxidative stress (oxidant risks) was considered.

SUBJECTS/METHODS

A retrospective record review of community-dwelling adults evaluated over a 12-year period for Cbl deficiency in a primary care setting who had serum Cbl values ⩾400 pg/ml (n=170).

RESULTS

When no oxidant risks were present, older subjects (⩾70 years) had higher metabolite values than younger individuals (<70 years). MMA values were even higher in the elderly when one oxidant risk was present and in younger subjects when two or more oxidant risks were present. Even at Cbl levels ⩾800 pg/ml, MMA values were increased in 73% of elderly subjects with at least one oxidant risk. HCys values were also higher in both age groups when at least two oxidant risks were present. Cyanocobalamin therapy decreased MMA and HCys values in 86 and 76% of subjects, respectively, with nonresponders more likely to have two or more oxidant risks.

CONCLUSION

Functional Cbl deficiency is associated with disorders marked by increased oxidative stress particularly in the elderly; it occurs even when Cbl levels are high and is not consistently corrected with high-dose cyanocobalamin therapy. Thus, current approaches to recognizing and managing this disorder may be inadequate.