Israel Medical Association Journal

Background: The recreational use of nitrous oxide (N₂O) has increased in recent years with a noticeable surge in the incidence of nitrous oxide-related myeloneuropathy.

Objectives: To raise awareness of increasing myeloneuropathy due to recreational nitrous oxide misuse in Israel.

Methods: We conducted a case series documenting the clinical and investigative features of eight patients presenting with nitrous oxide-induced myeloneuropathy who were admitted to our departments.

Results: Paresthesia was the chief complaint in all patients, with sensory gait ataxia being a common feature, which was often accompanied by Romberg's sign and mild lower limb weakness. Vitamin B12 levels were below the normal range in seven patients, accompanied by elevated homocysteine and methylmalonic acid levels. Magnetic resonance imaging scans revealed hyperintense signals in the dorsal columns of the cervical spine. All patients improved following vitamin B12 injections.

Conclusions: Enhancing awareness, prompting the use of appropriate investigations, and advocating for timely treatment are needed to overcome the risks associated with nitrous oxide misuse.

Background: Type 2 diabetes mellitus (T2DM) is a known risk factor for cardiovascular disease and stroke. Metformin is an old, relatively safe, first line therapy for T2DM; however, it has been associated with stroke.

Objectives: To study the effects of metformin use and vitamin B12 deficiency on stroke rate among patients with T2DM.

Methods: We conducted a prospective study of patients admitted with ischemic stroke within 12 months (starting March 2020). We studied the clinical impact of metformin on vitamin B12 deficiency and stroke evolution. Student's t-test and ANOVA were used to compare the groups of patients and to determine whether there was any direct or indirect effect of metformin use on vitamin B12 deficiency and stroke.

Results: In total, 80 patients were admitted with ischemic stroke. Clinical status and biochemical data were collected and compared with healthy volunteers. There were 39 diabetic patients, 16 took metformin for at least 1 year. Among those who took metformin for at least 1 year, 9 had vitamin B12 level < 240 pg/ml (56.2%); 23 diabetic patients did not get metformin and only 4 had vitamin B12 level < 240 pg/ml (17.4%) (P = 0.014).

Conclusions: T2DM is a significant risk factor to the development of ischemic stroke. We found an association between metformin use and vitamin B12 deficiency and an association between vitamin B12 deficiency and stroke risk in patients with T2DM. Diabetic patients who are taking metformin should monitor their vitamin B12 level.

Background: Low folate levels are associated with megaloblastic anemia, neural tube defects, and an increased risk of cancer. Data are scarce regarding the sex aspect of this deficiency.

Objectives: To assess sex differences in folate levels in a large cohort of patients and to investigate the effect of low folate levels on homocysteine concentrations.

Methods: Data were collected from medical records of patients examined at a screening center in Israel between 2000 and 2014. Cross sectional analysis was conducted on 9214 males and 4336 females.

Results: The average age was 48.4 ± 9.5 years for males and 47.6 ± 9.4 years for females. Average folate levels were 19.2 ± 8.6 and 22.4 ±10.3 nmol/L in males and females, respectively (P < 0.001). The prevalence of folate levels below 12.2 nmol/L was 19.5% in males compared to 11.6% in females (P < 0.001). In patients with low folate levels and normal B12 levels, homocysteine levels above 15 μmol/L were found in 32.4% of males and 11.4% of females (P < 0.001). Males had a significantly higher odds ratio (OR) of having folate levels below 12.2 nmol/L: OR 1.84 (95% confidence interval [95%CI] 1.66–2.05) in a non-adjusted model, and OR 2.02 (95%CI 1.82–2.27) adjusted for age, smoking status, body mass index, kidney function, albumin, and triglycerides levels.

Conclusions: Folate levels are lower in males compared to females, which may contribute to the higher homocysteine levels found in males and thus to their increased risk of developing atherosclerosis and coronary artery disease.

Abstract

Background: Hyperhomocysteinemia is associated with increased cardiovascular risk, but treatment with folic acid has no effect on outcome in unselected patient populations.

Objectives: To confirm previous observations on the association of homozygosity for the TT MTHFR genotype with B12 deficiency and endothelial dysfunction, and to investigate whether patients with B12 deficiency should be tested for 677MTHFR genotype.

Methods: We enrolled 100 individuals with B12 deficiency, tested them for the MTHFR C677T polymorphism and measured their homocysteine levels. Forearm endothelial function was checked in 23 B12-deficient individuals (13 with TT MTHFR genotype and 10 with CT or CC genotypes). Flow-mediated dilatation (FMD) was tested after short-term treatment with B12 and folic acid in 12 TT MTHFR homozygotes.

Results: Frequency of the TT MTHFR genotype was 28/100 (28%), compared with 47/313 (15%) in a previously published cohort of individuals with normal B12 levels (P = 0.005). Mean homocysteine level was 21.2 ± 16 mM among TT homozygotes as compared to 12.3 ± 5.6 mM in individuals with the CC or CT genotype (P = 0.008). FMD was abnormal (£ 6%) in 9/13 TT individuals with B12 deficiency (69%), and was still abnormal in 7/12 of those tested 6 weeks after B12 and folic treatment (58%).

Conclusions: Among individuals with B12 deficiency, the frequency of the TT MTHFR genotype was particularly high. The TT polymorphism was associated with endothelial dysfunction even after 6 weeks of treatment with B12 and folic acid. Based on our findings we suggest that B12 deficiency should be tested for MTHFR polymorphism to identify potential vascular abnormalities and increased cardiovascular risk. 

Background: Transcobalamin II is a serum transport protein for vitamin B₁₂. Small variations in TC-II[1] affinity were recently linked to a high homocysteine level and increased frequency of neural tube defects. Complete absence of TC-II or total functional abnormality causes tissue vitamin B₁₂ deficiency resulting in a severe disease with megaloblastic anemia and immunologic and intestinal abnormalities in the first months of life. This condition was described in hereditary autosomal-recessive form. Low serum TC-II without any symptoms or clinical significance was noted in relatives of affected homozygotes.

Objectives: To study 23 members of a four-generation family with hereditary vitamin B₁₂ deficiency and neurologic disorders.

Methods: Thorough neurologic, hematologic and family studies were supplemented by transcobalamin studies in 20 family members.

Results: Partial TC-II deficiency was found in 19 subjects. Apo TC- II (free TC-II unbound to vitamin B₁₂) and total unsaturated B₁₂ binding capacity were low in all tested individuals but one, and holo TC-II (TC-II bound by vitamin B₁₂) was low in all family members. The presentation of the disease was chronic rather than acute. Early signs in children and young adults were dyslexia, decreased IQ, vertigo, plantar clonus and personality disorders. Interestingly, affected children and young adults had normal or slightly decreased serum vitamin B₁₂ levels but were not anemic. Low serum B₁₂ levels were measured in early adulthood. In mid-late adulthood megaloblastic anemia and subacute combined degeneration of the spinal cord were diagnosed. Treatment with B₁₂ injections resulted in a significant improvement. The pedigree is compatible with an autosomal-dominant transmission. This family study suggests a genetic heterogeneity of TC-II deficiency.

Conclusions: We report the first family with a hereditary transmitted condition of low serum TC-II (partial TC-II deficiency) associated with neurologic and mental manifestations in childhood. Partial TC-II deficiency may decrease the amount of stored cobalamin, resulting in increased susceptibility to impaired intestinal delivery of cobalamin and predisposing to clinically expressed megaloblastic anemia at a later age. Partial TC-II deficiency should be suspected in families with megaloblastic anemia and in individuals with neurologic and mental disturbances – despite normal serum vitamin B₁₂ levels. Low serum UBBC[2] and apo TC-II should confirm the diagnosis. Early vitamin B₁₂ therapy may prevent irreversible neurologic damage.