Objective A recent study evidenced by metyrapone test a central adrenal insufficiency (CAI) in 60% of Prader–Willi syndrome (PWS) children. These results were not confirmed in investigations with low [Low-Dose Tetracosactrin Stimulation Test (LDTST), 1 μg] or standard-dose tetracosactrin stimulation tests. We extended the research by LDTST in paediatric patients with PWS.
Design Cross-sectional evaluation of adrenal stress response to LDTST in a PWS cohort of a tertiary care referral centre.
Patients Eighty-four children with PWS.
Measurements Assessment of adrenal response by morning cortisol and ACTH dosage, and 1-μg tetracosactrin test. Response was considered appropriate when cortisol reached 500 nm; below this threshold, patients were submitted to a second test. Responses were correlated with the patients’ clinical and molecular characteristics to assess genotype–phenotype correlation.
Results Pathological cortisol peak responses to the LDTST were registered in 12 patients (14·3%) who had reduced basal (169·4 ± 83·3 nm) and stimulated (428·1 ± 69·6 nm) cortisol levels compared to patients with normal responses (367·1 ± 170·6 and 775·9 ± 191·3 nm, P < 0·001). Body mass index standard deviation score was negatively correlated with basal and peak cortisol levels (both P < 0·001), and the patients’ ages (P < 0·001). In patients with deletion on chromosome 15, the cortisol peak was significantly lower than that in uniparental disomy (UPD) cases (P = 0·030). At multiple regression analysis, the predictors of peak response were basal cortisol, age, and UPD subclass (r2 = 0·353, P < 0·001). Standard-dose (250 μg) tetracosactrin test confirmed CAI in 4/12 patients (4·8% of the cohort).
Conclusions Our results support the hypothesis that, albeit rare, CAI may be part of the PWS in childhood.