Quantitative ultrasound bone profile and vitamin D status in 5-11 years old children with intellectual disability

To measure serum vitamin D levels and quantitative ultrasound bone profile parameters and their correlation with each other in children with various grades of intellectual disability and bone health.

The descriptive study was conducted from January to December, 2011, at the University of Health Sciences, Lahore, Pakistan, and comprised children aged 5-11 years having intelligence quotient less than 70. Quantitative ultrasound measurements at hand phalanges were taken using an ultrasonic bone profiler. Serum calcium, phosphate and alkaline phosphatase were measured by calorimetry and 25-hydroxy vitamin D levels were measured by enzyme-linked immunosorbent assay. Data was analysed using appropriate statistical tools.

Of the 61 children, 35 (57.4%) were boys and 26(42.6%) were girls. Overall median age was 104.48 months (inter quartile range: 77.77-128.04 months). Of the total, 17(27.9%) subjects had below normal bone profile and 51(85%) had less than 20ng/ml 25-hydroxy vitamin D levels. A mild negative correlation of 25-hydroxy vitamin D was seen with age (p=0.006). Moderate significant correlations of amplitude dependant speed of sound were observed with age (p<0.001) and alkaline phosphatase (p<0.001).

Significant proportion of children with intellectual disability had below-normal bone profile. Vitamin D levels were extremely low in overwhelming majority of children with intellectual disability. Significant negative correlation of age with Vitamin D and positive correlation with amplitude dependant speed of sound may suggest increasing requirements of vitamin D with age to cope with advancing needs of growing skeleton in children with intellectual disability.