School of Clinical Medicine (ETDs)

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Browsing School of Clinical Medicine (ETDs) by Keyword "25-hydroxyvitamin- D (25(OH)D)"

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    Adolescent fractures and vitamin D status: The Birth to Twenty cohort
    (University of the Witwatersrand, Johannesburg, 2024) Selebeleng, Morakane Violet; Thandrayen, Kebashni
    Background: Fractures are common in childhood and previous studies on the Birth to twenty cohort (Bt20) found that adolescent males had higher fracture rates than the females and white males had the highest fracture rates. The association between fractures and 25-hydroxyvitamin- D (25(OH)D) levels has not been investigated in this cohort. Objectives: The association between 25(OH)D levels at 10 years and fracture risk within the first 10 and 15 years of life was assessed. Methods: Data analysis of the Bone Health sub-cohort of the Bt20 cohort (children born in 1990 and residing in Johannesburg) was done and children with 25(OH)D levels at 10 years were included in the study. Body mass index (BMI), dual-energy X-ray absorptiometry scan measurements and physical activity (PA) scores performed at 10 and 15 years were converted to Z-scores. Fracture risk (within 10 and 15 years of life) and 25(OH)D were assessed in relation to the above measurements. Results: Data from 385 children was analysed; 72% were black children, 58% were males. At 10 years, 13% of the children had fractured and by 15 years 21%. The median 25(OH)D level was 96.9 nmol/L (interquartile range 73.3;120.5) with insufficient levels (<50 nmol/L) in 6.5% and deficiency (<30 nmol/L) in 0.25%. No differences were noted in 25(OH)D levels between the fractured and non-fractured groups with only 4 of the 50 who fractured having insufficient levels. The levels were not influenced by gender, ethnicity, BMI or PA. A greater proportion of white than black children fractured at both 10 (24% vs 9%; p<0.001) and 15 years of age (36% vs 15%; p<0.001). White children who fractured had higher formal PA scores at 15 years compared to black children. An increase in lean mass was associated with increased fracture risk at 15 years (adjusted OR 1.23 (CI 1.00;1.51)). Conclusion The risk of fracturing in children is multifactorial and 25(OH)D levels did not affect risk of fracturing, although only a small proportion had low 25(OH)D levels. Higher lean mass increased the risk for fracturing at 15 years and white children were two times more likely to fracture compared to black children