The effects of sampling lateralization on bilateral inferior petrosal sinus sampling and desmopressin stimulation test for pediatric Cushing's disease

PURPOSE: Bilateral inferior petrosal sinus sampling (BIPSS) is useful for differential diagnosis of adult Cushing’s disease (CD) but may not be so reliable in pediatric cases. The purpose of this study was to evaluate the sensitivity of BIPSS before and after desmopressin stimulation in pediatric CD, and to explore related factors of false-negative results and meanings of sampling lateralization. METHODS: We retrospectively analyzed 16 pediatric CD patients who underwent 17 BIPSS procedures from 2006 to 2017. CD was diagnosed if inferior petrosal sinus (IPS) to peripheral adrenocorticotropic hormone (ACTH) ratio was >2 at baseline or >3 after desmopressin stimulation. Sampling lateralization was yielded if interpetrosal sinus gradient was >1.4. Magnetic resonance imaging (MRI) was conducted. All the patients underwent surgery and the diagnosis was confirmed. RESULTS: The sensitivity was 64.7% (11/17) at baseline and 83.3% (10/12) after desmopressin stimulation. After stimulation, BIPSS reached its best sensitivity at 3 min. Sampling lateralization rate was 62.5% and 63.6% before and after stimulation, and the accordant rate with actual tumor lateralization was 50.0% and 42.9%, respectively. The accuracy of MRI in predicting the tumor lateralization was 80.0%. Sampling lateralization rate (81.8% in true-positive, 20.0% in false-negative, p = 0.036) and ACTH at dominant IPS (p = 0.001) was lower among false-negative patients. CONCLUSIONS: The sensitivity of BIPSS in pediatric CD was low at baseline, but increased after desmopressin stimulation. Sampling lateralization cannot accurately indicate the tumor lateralization, but the absence of sampling lateralization with low ACTH at IPS is a hint of false-negative cases in BIPSS.