Ultrasonographic measurements of the skin, fat and muscle in vitamin D deficiency.

Background: Vitamin D is a steroid hormone and it is essential for the musculoskeletal system health. The relationship among vitamin D levels and adiposity was shown. However, there is only one study seems to have examined the relationship between skinfold thickness and vitamin D levels.

Methods: A total of 116 healthy subjects who had a recent vitamin D measurement were included. Skin, subcutaneous fat and muscle thicknesses were measured by ultrasound (US). Hand grip strength and usual gait speed were evaluated.

Results: Subjects were classified into two groups according to 25-OH vitamin D levels. Skin thicknesses of anterior forearm in women and of anterior tibia in men, and trochanteric fat thicknesses of both genders were higher in lower 25-OH vitamin D group (both P < .05). There were no differences between the groups regarding muscle thicknesses, grip strength and gait speed (all P > .05). For identifying vitamin D deficiency (≤20 ng/mL); optimal skin thickness value was 1.25 mm in women (sensitivity: 91.3%, specificity: 54.7%), and optimal trochanteric fat thickness was 1.79 cm in men (sensitivity: 87.5%, specificity: 76.9). The specificity was increased to 79.2% if the cut-off value was taken as 1.35 mm for anterior forearm skin thickness in women.

Conclusion: We imply that skin thicknesses (anterior forearm and tibia) and subcutaneous fat (trochanteric region) increase in subjects with low vitamin D levels. Having also ascertained the relevant cut-off values, we underscore the possible role of these measurements as regards the assessment of vitamin D status.