ESPE Abstracts

Introduction: BIPSS before and after desmopressin stimulation has been shown to be a useful tool for diagnosis of ACTH-dependent CD and negative magnetic resonance imaging (MRI)or positive MRI but inconsistent biochemical data, in adult patients. However, little is known about its usefulness in pediatric population.

Objective: To evaluate the prevalence of negative MRI, the sensitivity of BIPSS before and after desmopressin stimulation for CD diagnosis and the tumor localization in a pediatric population.

Design: It is a retrospective study.Twenty-three pediatric patients, (10 males), mean age: 12.6± 2.5years (y) (range 5.9-17.3) followed in a single tertiary centre were included. All the patients had hypothalamic pituitary MRI and biochemical diagnosis of CD.In case of negative MRI, patients underwent BIPSS. CD was suspected if inferior petrosal sinus (IPS) to peripherical (P) ACTH ratio was > 2 at baseline and > 3 after desmopressin stimulation. Lateralization was define if IPS gradient was >1.4.Diagnosis of CD was confirmed by surgery and/or clinical evolution.

Results: Seven out of 23 patients had negative MRI (30.4%) and underwent BIPSS, (3 males and 4 females), mean age: 11.6 ± 3 y (range 5.9 -14.1). Technical success rate was 100% for bilateral cannulation and no complications were recorded. In all patient baseline IPS/P ratio was > 2, sensitivity 100%. All but one patient had IPS/P ratio after desmopressin > 3, sensitivity 85 %.Sampling predicted tumor lateralization in 4/7 patients (sensitivity 57%).IPS/P ratio pick was at 3 minutes, except in the patient who did not respond to desmopressin.Only one patient, different from the no responding desmopressin test patient,had persistent disease after surgery.

Conclusion: The prevalence of negative MRI was similar to that described in adult patients. BIPSS basal and after desmopressin was safe and highly sensitive for the diagnosis of CD in this pediatric population. The time of BIPSS after desmopressin might be reduced without affecting the sensitivity. BIPSS was not sensitive enough for the correct lateralization of the pituitary tumor. More data are needed to confirm our results.