Diagnosing metabolic syndrome in craniopharyngioma patients: body composition versus BMI

Craniopharyngioma patients often have poor metabolic profiles due to hypothalamic-pituitary damage. Previously, using BMI as obesity marker, the occurrence of the metabolic syndrome in these patients was estimated at 46%. Our aim was to determine if dual X-ray absorptiometry (DXA) scan in evaluation of obesity and metabolic syndrome would be superior.

Retrospective study of craniopharyngioma patients for whom DXA scan results were available.

BMI, fat percentage and fat mass index were used to evaluate obesity and as components for obesity in metabolic syndrome.

Ninety-five craniopharyngioma patients were included (51% female, 49% childhood-onset disease). Metabolic syndrome occurred in 34-53 (45-51%) subjects (depending on the definition of obesity, although all definitions occurred in higher frequency than in the general population). Metabolic syndrome frequency was higher if obesity was defined by fat percentage (52 vs 42%) or fat mass index (51 vs 43%) compared to BMI. Misclassification appeared in 9% (fat percentage vs BMI) and 7% (fat mass index vs BMI) for metabolic syndrome and 29 and 13% for obesity itself, respectively. For metabolic syndrome, almost perfect agreement was found for BMI compared with fat percentage or fat mass index. For obesity, agreement was fair to moderate (BMI vs fat percentage).

Using BMI to evaluate obesity underestimates the true prevalence of metabolic syndrome in patients with craniopharyngioma. Furthermore, fat percentage contributes to a better evaluation of obesity than BMI. The contribution of DXA scan might be limited for identification of the metabolic syndrome.