Body composition in premature adrenarche by structural MRI, 1H MRS and DXA

Muscle fat content and abdominal adipose tissue distribution investigated by magnetic resonance spectroscopy and imaging in obese children and youths

The degree of fat deposition in muscle and its implications for obesity-related complications in children and youths are not well understood. One hundred and fifty-nine patients (mean age: 13.3 years; range: 6-20) with a body mass index (BMI) >90(th) percentile for age and sex were included. Muscle fat content (MFC) was measured in the psoas muscle by proton magnetic resonance spectroscopy. The patients were assigned to two groups: MFC <5% or ≥5%. Visceral adipose tissue volume (VAT) and subcutaneous adipose tissue volume (SAT) were measured by magnetic resonance imaging. The data were analysed to detect associations between MFC and BMI standard deviation scores, VAT and SAT, blood values, pubertal stages, and physical activity scores. The mean BMI standard deviation score (SDS) was 3.04 (range 1.32-5.02). The mean MFC was 8.9% (range 0.8-46.7), and 118 (74.2%) of 159 patients had an MFC ≥5%. Children with an MFC ≥5%, compared with children with an MFC <5%, had a higher BMI SDS (P=0.03), a higher VAT (P=0.04), and elevated intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) contents (both P<0.0001). SAT, SAT/VAT ratio, blood values, pubertal stages and physical activity scores did not differ between the two groups. Severely obese children and youths tend to have a high MFC, which is associated with elevated VAT, IMCL, and EMCL contents. An increased MFC may be associated with impaired metabolic processes, which may predispose these young people to obesity-related complications.

Approach to the girl with early onset of pubic hair

Premature pubarche, or the development of pubic hair before the age of 8 in girls or 9 in boys, is most commonly caused by premature adrenarche. Adrenarche is the maturation of the adrenal zona reticularis in both boys and girls, resulting in the development of pubic hair, axillary hair, and adult apocrine body odor. Although originally thought to be a benign variant of normal development, premature adrenarche has been associated with insulin resistance and the later development of metabolic syndrome and polycystic ovary syndrome. Although further studies are needed to confirm these relationships, the case presented herein argues for periodic assessment of children at risk. Indeed, recognition of these associations may allow for early preventive measures.