medwireNews: Measuring hair cortisol levels may help to identify overtreatment of children with adrenal insufficiency receiving glucocorticoid replacement therapy, research suggests.

“The method is relatively simple, easily implemented and noninvasive, making it especially suitable in the paediatric clinical practice”, say study author Erica van den Akker (Erasmus MC, Rotterdam, the Netherlands) and colleagues.

They note, however, that cortisol only becomes detectable in hair after about 1 month of treatment.

The team found that hair cortisol levels were significantly higher in 54 children, aged 4 to 18 years, receiving hydrocortisone than in 54 age- and gender-matched healthy children, at an average of 13·3 versus 8·2 pg/mg. Among the patients, levels were 11.8 pg/mg in 10 children with Addison’s disease, 13·4 pg/mg in 31 with congenital adrenal hyperplasia and 14·6 pg/mg in 13 children with central adrenal insufficiency.

Patients were shorter than the control children, on average, and had a significantly higher average waist circumference and body mass index (BMI).

The researchers believe that the increased hair cortisol levels in the patients suggests that “adrenal insufficiency patients are on average overtreated with hydrocortisone, resulting in the hallmark sequelae of hypercortisolism such as increased BMI and central adiposity.”

They note that these effects of overtreatment were observed despite all the children being treated according to national glucocorticoid replacement guidelines.

Hair cortisol levels were significantly associated with waist circumference and BMI standard deviation score (SDS), but not with height. Further analysis indicated that 12·7% of the difference in BMI SDS and 29·2% of the difference in waist circumference SDS were accounted for by hair cortisol levels.

However, hair cortisol levels did not correlate with hydrocortisone dose, which the team attributes to highly variable absorption, metabolism and excretion between patients, especially given that cortisol pharmacokinetics “undergo marked changes during puberty.”

“Measurement of cortisol concentrations in scalp hair reflecting long-term systemic cortisol exposure at the tissue level may provide a new method for identifying hydrocortisone overtreatment in patients with adrenal insufficiency”, writes the team in Clinical Endocrinology.

“This may improve current glucocorticoid replacement quality, limiting long-term negative health effects of previously unobserved overtreatment.”

By Eleanor McDermid, Senior medwireNews Reporter

Clin Endocrinol 2014; Advance online publication

Free Abstract