Abstract 132: Pituitary stalk interruption syndrome: Clinical, hormonal and radiological characteristics, predictors of multiple pituitary hormone deficiency and response to growth hormone therapy

Background: PSIS is a rare entity characterized by a triad of an absent or hypoplastic anterior pituitary, thin or absent infundibulum and/ or ectopic posterior pituitary. PSIS has multiple theories for its cause: perinatal injury/ genetic abnormalities/ multifactorial causing defective pituitary development leading to MPHD. Objective: The primary objectives were to evaluate the clinical characteristics, hormonal abnormalities of the pituitary stalk interruption syndrome (PSIS) patients at presentation and determining the predictors for Multiple Pituitary Hormone Deficiency (MPHD). The secondary objectives were to assess the response of rGH therapy and development of new pituitary hormonal deficiencies during follow up. Methods: This retrospective longitudinal study involves 14 PSIS patients confirmed radiologically presenting to Endocrinology department in Gauhati Medical College, Guwahati, Assam from 2017 to 2022. All other causes of pituitary hormonal deficiencies were excluded. Statistical data were analyzed using XLSTAT software with chi squared test and t test, Pearson correlation for categorical and continuous variables respectively. Descriptive analysis was expressed in terms of mean, median and percentages. Results: Majority of the PSIS patients were male (n = 10, 71%) with median age of presentation (12.15 years) and short stature being the most common presenting complaint (n = 13, 93%) and one patient (2-month child) presented with hypoglycemia. Midline defects seen were micropenis (n = 4, 29%), cleft lip (n = 1, 7%) and single central incisor (n = 1, 7%). Among the hormonal axis, GH deficiency was the most common (n = 14, 100%) followed by T4 (n = 5, 36%), cortisol (n = 4, 29%) deficiency and none had Diabetes Inspidus. Gonadotropin (Gn)(n = 2) deficiency was seen in 2/4 patients with delayed puberty. Among radiological characteristics, anterior pituitary hypoplasia is most common (n = 13) followed by ectopic posterior pituitary bright spot (PPBS) (n = 11), thinned out stalk (n = 5) and absent PPBS (n = 3). The predictors of MPHD were hyperprolactinemia (x2 -7.77, p-0.005) and midline defects (x2 -4.66, p- 0.03). On follow up, 4 patients developed new hormonal deficiencies with T4 deficiency (n = 2), cortisol def (n = 2) and Gn deficiency (n = 1). Patients showed good response to rGH therapy with initial mean requirement of 0.20 mg/kg/week with mean height velocity- 12.78 cm in 1st year (p < 0.001) and significant increase in IGF1 and height SDS (p < 0.001). Conclusions: PSIS causes MPHD and diagnosing and following up these patients is important for early identification of new hormonal deficiencies and optimal hormone replacement.