PHYSICAL EXAMINATION

LABORATORY STUDIES

DIAGNOSIS

Panhypopituitarism

PATHOPHYSIOLOGY OF KEY SYMPTOMS

The patient exhibits a variety of symptoms involving the reproductive system, cardiovascular system, fluid balance, and metabolism. In most cases, the symptoms reflect a diminished end organ response from the targets of pituitary gland hormones. In one instance, the symptom of galactorrhea reflects the overproduction of pituitary prolactin. This grouping of symptoms is characteristic of damage to the pituitary stalk, separating the pituitary from the hypothalamic control.

The pituitary gland is a mixed neuronal and endocrine structure that is connected to the hypothalamus by the hypophyseal stalk (Fig. 76-1). The posterior pituitary is neural in origin and secretes the hormones oxytocin and antidiuretic hormone (ADH, vasopressin). The cell bodies synthesizing these hormones are in the supraoptic and paraventricular nuclei of the hypothalamus. The anterior pituitary is a glandular tissue that secretes six physiologically important hormones: adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), growth hormone (GH), luteinizing hormone (LH), prolactin, and thyroid-stimulating hormone (TSH). Pituitary gland secretions control metabolism, reproduction, growth, and fluid balance. Consequently, the pituitary is often referred to as the master gland.

FIGURE 76–1 The hypothalamus and pituitary have complex neural and endocrine interactions. Neurons in the hypothalamus synthesize oxytocin and antidiuretic hormone. The hormones are transported within axon terminals to the posterior pituitary for release. In contrast, the anterior pituitary is an endocrine gland. Hormone release is controlled by releasing inhibitory peptides that pass from the hypothalamus to the anterior pituitary by a vascular hypothalamic-hypophyseal portal system.