Endocrine Abstracts

The pituitary gland is the master gland controlling many other hormone secreting organs.The gland lies within the sella turcica at the base of the brain to which it is attached by the pituitary stalk or infundibulum. Lactotrophs, somatotrophs, thyrotrophs, corticotrophs and gonadotrophs in the anterior pituitary gland secrete the polypeptide hormones prolactin (PRL), growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH) and luteinizing (LH) and follicle stimulating (FSH) hormones, respectively, and magnocellular neurosecretory neurons in the posterior gland extending from the Paraventricular nucleus and Supraoptic nucleus in the hypothalamus, secrete Vasopressin and Oxytocin. The pituitary gland is derived from two ectodermal structures, the neural ectoderm, which gives rise to the posterior lobe, and the surface ectoderm, which produces Rathke’s pouch, the precursor to the anterior and intermediate lobes. Specific transcription factors are important for cell specification and lineage determination. Knowledge of pituitary development and transcription factors helps to determine the cause of congenital pituitary hormone deficiency disorders, either isolated hormone deficiency or multiple hormone deficiency, either as an isolated hormone condition or in the context of a syndrome, for example sept-optic dysplasia, holoprosencephaly, Kalmann syndrome, CHARGE syndrome, Coffin Siris syndrome. Pituitary hormone secretion is mostly pulsatile and regulated by neuroendocrine factors produced in neuroendocrine cells in the hypothalamic nuclei and secreted in the portal circulation to act on surface receptors of anterior pituitary cells. We will discuss the regulation of GH secretion in the hypothalamic–pituitary axis in more detail and relate it to different types of isolated GH deficiency and touch on the effects of GH resistance on GH secretion. The pulsatile nature of pituitary hormone secretion is a challenge for the investigation of pituitary hormone deficiencies, reason to resort to pituitary stimulation tests which however require cautious interpretation in conjunction with other investigations and the clinical phenotype of the patient in order to prevent incorrect diagnosis of pituitary hormone deficiency. Lastly, we will touch on acquired causes of pituitary hormone deficiencies, such as craniopharyngioma.