Endocrine Abstracts

Introduction: Measurement of the anterior pituitary hormone prolactin is often performed in patients with pituitary pathology. Mild hyperprolactinemia occurs in subjects with hypothalamic disorders and/or pituitary stalk dysfunction, and is also described in patients with isolated optic nerve hypoplasia (ONH), this is proposed to be due to decreased dopaminergic tone.

Objective: To assess prolactin levels in patients with septo-optic dysplasia (SOD) (with/without hypopituitarism), multiple pituitary hormone deficiency (MPHD), isolated GH deficiency (IGHD) and isolated optic nerve hypoplasia (ONH).

Methods: Prolactin data were retrospectively analysed from our database of children with SOD, MPHD, IGHD and ONH. Prolactin was measured using the Immulite assay. 238 prolactin results were included: patients with SOD and hypopituitarism (n=56), SOD with normal endocrine function (19), MPHD (73), IGHD (76) and ONH (uni- and bi-lateral) (14). Prolactin concentrations were compared using analysis of covariance using SPSS.

Results: The mean prolactin levels in patients with SOD with hypopituitarism was 448.9 mU/l and in those with SOD and normal pituitary function was 339.1 mU/l. MPHD, IGHD and ONH patients had mean prolactin concentrations of 295.4, 185.2 and 284.6 mU/l respectively. Children with SOD and hypopituitarism had higher levels than those with MPHD (P=0.008) and IGHD (P≤0.001). Four SOD patients (three with hypopituitarism) and two with MPHD had prolactin levels >1000 mU/l. Five children with MPHD had prolactin levels below the lower limit of the assay; one is known to have a POU1F1 mutation. Mean prolactin concentrations in children with ONH and SOD without hypopitutarism were similar to the other groups, although a greater sample size is required to report this with confidence.

Conclusion: Prolactin is often measured in patients with suspected pituitary dysfunction. Higher prolactin levels are found in SOD patients with hypopituitarism. Undetectable prolactin levels in MPHD patients should instigate investigation of genetic causes.