Severe Hypoglycemia and Pituitary Stalk Interruption Syndrome in a 5-Year-Old Boy with Coexistent Hyperprolinaemia: A Case Report and Literature Review

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Background/Objectives: Hyperprolinemia is a rare autosomal recessive disorder with two distinct types: I (HPI) and II (HPII). The clinical presentation varies widely, with some individuals remaining asymptomatic and others exhibiting neurological, renal, or auditory defects and seizures. However, it has never been associated with hypoglycemia. The present case report describes a 5-year and 6/12-month-old boy with HPII, with an episode of severe hypoglycemia and Pituitary Stalk Interruption Syndrome (PSIS) with isolated growth hormone (GH) deficiency (GHD). Results: The boy was presented to the Department of Pediatric Endocrinology for routine thyroid function assessment due to hypothyroidism. He was diagnosed with HPII at the age of 2 years old during an investigation for seizure episodes. Clinically, the boy exhibited attention deficit hyperactivity disorder (ADHD) and a reduction in growth velocity (1.6 cm/year). Hematological and biochemical analyses were within the reference range. Hormone profiling revealed lower-than-expected insulin-like growth factor-1 (IGF-1) concentrations, prompting a GH stimulation test, which, in turn, revealed GHD. Brain magnetic resonance imaging (MRI) showed features consistent with PSIS. Noteworthy is the occurrence of severe hypoglycemia during an episode of gastroenteritis, leading to hospitalization, eventually attributed to GHD. Following the exogenous administration of recombinant human GH, the boy exhibited increased growth velocity, with no adverse events over the follow-up period. Conclusions: Hyperprolinemia is a rare condition; in this context, the occurrence of severe hypoglycemia accompanied by a low growth velocity poses a challenge for the clinical pediatrician. Furthermore, the coexistence of hyperprolinemia and PSIS has never been reported in the literature thus far.