Disorders of the Anterior Pituitary and Hypothalamus

Disorders of the Anterior Pituitary and Hypothalamus is a topic covered in the Harrison's Manual of Medicine.

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The anterior pituitary is often referred to as the “master gland” because, together with the hypothalamus, it orchestrates the complex regulatory functions of multiple other glands (Fig. 168-1). The anterior pituitary produces six major hormones: (1) prolactin (PRL), (2) growth hormone (GH), (3) adrenocorticotropin hormone (ACTH), (4) luteinizing hormone (LH), (5) follicle-stimulating hormone (FSH), and (6) thyroid-stimulating hormone (TSH). Pituitary hormones are secreted in a pulsatile manner, reflecting intermittent stimulation by specific hypothalamic-releasing factors. Each of these pituitary hormones elicits specific responses in peripheral target glands. The hormonal products of these peripheral glands, in turn, exert feedback control at the level of the hypothalamus and pituitary to modulate pituitary function. Disorders of the pituitary include neoplasms or other lesions (granulomas, hemorrhage) that lead to mass effects and clinical syndromes due to excess or deficiency of one or more pituitary hormones.

FIGURE 168-1

Diagram of pituitary axes. Hypothalamic hormones regulate anterior pituitary tropic hormones that, in turn, determine target gland secretion. Peripheral hormones feedback to regulate hypothalamic and pituitary hormones. ACTH, adrenocorticotropin hormone; CRH, corticotropin-releasing hormone; FSH, follicle-stimulating hormone; GH, growth hormone; GHRH, growth hormone–releasing hormone; GnRH, gonadotropin-releasing hormone; IGF, insulin-like growth factor; LH, luteinizing hormone; PRL, prolactin; SRIF, somatostatin, somatotropin release–inhibiting factor; TRH, thyrotropin-releasing hormone; TSH, thyroid-stimulating hormone.

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