Objectives: Studies have suggested a significant link between vitamin D status and asthma. We sought to determine the cutoff level of25 hydroxy (25-OH) vitamin D that is significantly linked to asthma status in children. Methods: Our cross-sectional study comprised 90 asthmatic children, aged 2-18 years. They were evaluated clinically and classified according to asthma severity and control. Asthma control test (ACT) was performed in those aged above 4 years. Pulmonary functions were performed

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... cooperative children (n=59). Serum 25-OH vitamin D levels were measured by ELISA in all patients. Results: The study comprised 52 boys (57.7%) and 38 girls (42.3%) with mean age 7.03±4.36 years. Thirty-six patients (40%) had mild asthma, 37 (41%) moderate asthma and 17 (19%) had severe asthma. Forty-two patients (46.6%) had controlled asthma; 14 (15.6%) partially controlled and 34 (37.8%) had uncontrolled asthma. ACT score ranged: 11-26, with mean score: 18.9 ± 4.3 SD. Serum 25-OHvitamin D levels ranged between 2-48 ng/ml (mean± SD: 12.2 ± 9 ng/ml); levels were comparable among different grades of asthma severity (f= 1.975, p=0.145), while the uncontrolled asthma group showed the lowest levels (f=8.511, p <0.001). 25-OH vitamin D levels correlated positively with ACT score (r= 0.369, p= <0.001) but not with inhaled steroids doses or any of the pulmonary function parameters. A level of 7.5 ng/ml was associated with partial/complete uncontrol of asthma with 81 % sensitivity and 53 % specificity. Conclusion: 25-OH vitamin D levels below 7.5 ng/ml are associated with poor asthma status in children.