Israel Medical Association Journal

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.

Background: Both cigarette smoking and chronic kidney disease (CKD) are linked to cardiovascular morbidity and development of atherosclerosis. However, the relationship between cigarette smoking and renal function is not clearly understood. 

Objectives: To investigate the relationship between cigarette smoking and renal function, and determine whether the intensity of cigarette smoking influences renal function.

Methods: We conducted a retrospective analysis of subjects attending the screening center at the Rabin Medical Center. Subjects were classified as smokers, non-smokers and past smokers. Renal function was evaluated by means of the CKD-EPI equation for estimating glomerular filtration rate (eGFR). Multivariate and gender-based analyses were performed.

Results: The study population comprised 24,081 participants, of whom 3958 (17%) were classified current smokers, and 20,123 non-smokers of whom 4523 were classified as past smokers. Current smokers presented a higher eGFR compared to the non-smoking group (100.8 vs. 98.7, P < 0.001) as well as higher rates of proteinuria (15.3% vs. 9.3%, P < 0.001). The difference in eGFR between smokers and non-smokers was more significant in males than in females. Past smokers had the lowest eGFR of all groups, this difference remained significant after age adjustments (P = 0.005). 

Conclusions: Cigarette smoking is associated with higher eGFR compared to non-smoking. This difference was more pronounced in males than females, implying a gender-based difference. The higher prevalence of proteinuria in smokers suggests a mechanism of hyperfiltration, which might result in future progressive renal damage.