The endocrine system is composed of ductless glands that releases hormones directly into the bloodstream. The major organ of this system is the hypothalamus, which controls most of the endocrinal activity of the pituitary gland. It secretes “releasing hormones” i.e. growth hormone-releasing hormone (GRHR), corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), prolactin-inhibiting factor (PIF) and prolactin-releasing hormone (PRH).
Pituitary Gland (Hypophysis)
The pituitary gland is responsible for the production of various hormones, which it then releases based on signals from the hypothalamus. It is subdivided into two lobes:
Anterior Pituitary Gland (Adenohypophysis; Pars Anterior)
The anterior lobe constitutes 70% of the gland and is found in the sella turcica, a depression in the sphenoid bone at the base of the brain. Its secretions include: growth hormone (GH), prolactin (PRL), adrenocorticotrophic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), melanocyte-stimulating hormone (MSH)
Posterior Pituitary Gland (Neurohypophysis; Pars Posterior)
The posterior lobe constitutes the remaining 30% of the gland. It is responsible for the secretion of oxytocin and the antidiuretic hormone (ADH; vasopressin). However, it does not produce the hormones. It simply stores these hormones which are produced by the hypothalamus.
Hyperpituitarism
A chronic, progressive hyperfunctioning of the anterior pituitary results in over-secretion of hormone/s secreted by the adenohypophysis. It may be caused by:
- Benign pituitary adenoma (tumors)
- Hyperplasia of the pituitary tissue
- Prolactinomas: prolactin-secreting tumors, accounts for 60 to 80% of all pituitary tumors.
- Growth hormone-producing adenomas (tumors)
Assessment Findings
- Acromegaly, a gradual, marked enlargement of the bones of the face, jaw, hands, and feet as a result of Hypersecretion: GH. This may also include diaphoresis, hyperglycemia, oily skin, and hirsutism (inappropriate male-pattern hair growth in women)
- Gigantism, a proportional overgrowth of all body tissues with remarkable height. Also a result of Hypersecretion: GH.
- Neurologic Manifestations:
- Headaches, somnolence, behavioral changes, seizures, increased ICP symptoms
- Disturbances in appetite, sleep, body temperature, and emotional balance. These are all due to hypothalamic involvement.
- Visual disturbances as a result of the involvement of the optic chiasm situated just above the pituitary gland; hemianopsia (loss of a vertical half of vision), scotoma (a blind spot), or blindness.
Diagnostic Examination
- Skull X-ray, CT Scan, MRI all for visualization of tumors or hyperplasia.
- Plasma GH levels are elevated; normal range for:
- an adult male is 4 to 10 ng/ml
- an adult female is 1 to 14 ng/ml
- children have from 10 to 50 ng/ml
Nursing Interventions
Pre-operative Care
Health Teaching about the nature of the procedure and what to expect; nasal catheterization and nasal packing are to be expected for about a day. An indwelling catheter will be used for UO monitoring (post-op) as diabetes insipidus (DI) may be a complication of the surgery from inadequacy of ADH.
Post-operative Care
- Bed rest for ~24 hours. Encourage ambulation the following day.
- Fowler’s position alleviated ICP and pressure on the suture line; sneezing, forceful coughing, bending over, and blowing the nose all disturb the suture line and should be avoided.
- Mild analgesics may be used for headaches.
- Anticipate diabetes insipidus (DI): shows increased thirst and excessive urine output with low specific gravity.
- Replace fluids and administer IV ADH as ordered. Resolution within 72 hours is appropriate.
- UO of greater than 900 ml in 2 hours, or a specific gravity of <1.004 is indicative of DI.
Medical Management
Radiation Therapy
Drug Therapy
- Bromocriptine (Parlodel) inhibits the synthesis of GH and Prolactin. It may be used to treat amenorrhea, infertility, galactorrhea, hypogonadism, and Parkinson’s disease.
Surgical Management
- Removal of the pituitary gland; a transsphenoidal hypophysectomy.
Growth Hormone (Somatotropin)
The growth hormone (GH; pars anterior) manages the growth of body tissues (somato-) and bone.
Hypersecretion: GH
- Results in gigantism (disorder appears before fusion of long bone epiphyses, leading to excessive vertical growth) in children
- Results in acromegaly (disorder appears after fusion of long bone epiphyses, leading to large extremities and characteristic facies) in adults
Hyposecretion: GH
- Results in dwarfism, a lack of physical development, resulting in short stature.
Prolactin (Mammotrophic/Lactotrophic Hormone)
The prolactin hormone (PLT) manages mammary tissue growth and milk production.
Hypersecretion: PRL
- Galactorrhea: abnormal production and discharge of breast milk
Hyposecretion: PRL
- Agalactorrhea: lactational insufficiency; decreased or absent milk production during lactational periods.
Adrenocorticotrophic Hormone (ACTH)
This hormone signals for the adrenal cortex to secrete the adrenal hormones cortisol (the “stress” hormone) and aldosterone (the “salt-saving” hormone). The primary affected hormone in disorders related to ACTH is cortisol, but aldosterone may also be affected.
- Cortisol is a glucocorticoid, which increases the breakdown of fat and protein for energy use and reduces inflammatory and immune responses. It is released in response to waking up, exercise, or stressful events.
- Aldosterone is a mineralocorticoid, which increases water and sodium retention (hence “salt-saving”), and potassium to be excreted. It is indirectly involved with blood volume (and pressure) control. Further discussed: Pheochromocytoma, Cushing’s Syndrome, Addison’s Disease.
Hypersecretion: ACTH
Overproduction of ACTH increases cortisol levels in the blood. This results in Cushing’s Syndrome. This results in increased serum ACTH and cortisol levels, mild hypernatremia, hypokalemia, and hyperglycemia (all as a result of the function of cortisol). Clients with long-standing ACTH have an obese trunk and pendulous abdomen with thin extremities.
Hyposecretion: ACTH
A decrease in ACTH results in inadequate cortisol levels in the blood. This results in Addison’s Disease. This results in decreased ACTH and cortisol levels, hyponatremia and hypovolemia, hyperkalemia, acidosis, and hypoglycemia.
Thyroid Stimulating Hormone (TSH)
TSH stimulates the thyroid (real) to secrete T3 (Triiodothyronine) used for metabolism and growth, and T4 (Thyroxine, Tetraiodothyronine) used for catabolism and body heat production. Further discussed on Thyroid Disorders
Hypersecretion: TSH
Hyperthyroidism (Thyrotoxicosis) e.g. Grave’s Disorder, Basedow’s Disorder, Exophthalmic Goiter, Diffuse Toxic Goiter. An increase in thyroid hormones
Hyposecretion: TSH
Hypothyroidism. A decrease in thyroid hormones. Halting their processes, a notable decrease in metabolism and body heat production is noted. Physical and mental reactions are slow, and apathy may be observed; a dull, expressionless, mask-like face.
Gonadotropins
The gonadotropins, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), affect growth, maturity and the functioning of the primary and secondary sex characteristics. These affect the gonads (ovaries and testes), which in turn produces estrogen, progesterone, and testosterone.
Hypersecretion: Gonadotropins
Due to their role in the development of sex characteristics, too many gonadotropins will result in precocious puberty.
Hyposecretion: Gonadotropins
Inadequate gonadotropin production results in the delay or lack of sexual development results in impotence and substandard spermatogenesis for men, and the absence of ovulation, menstruation, and resultant infertility in women.
Melanocyte Stimulating Hormone (MSH)
Melanocytes are cells responsible for the production of melanin (pigment) production.
Hypersecretion: MSH
Overproduction of melanin results in hyperpigmentation of the skin, giving it a bronze-like appearance.
Hyposecretion: MSH
Underproduction of melanin results in hypopigmentation of the skin, giving it a pale appearance (albinism), either entirely or in patches.
Antidiuretic Hormone (ADH; Vasopressin)
The antidiuretic hormone counteracts diuresis by stimulating fluid retention in the kidneys (yet not affecting sodium excretion). It also causes vasoconstriction (hence the name “vasopressin”). Further discussed: Diabetes Insipidus (DI) and Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
Hypersecretion: ADH
- Persistently high levels of ADH in without any stimulation results in the excessive retention of water, also known as the syndrome of inappropriate antidiuretic hormone (SIADH).
Hyposecretion: ADH
- Inadequate ADH production results in the inability for the urinary system to concentrate urine (renal tubes to retain water), causing excessive fluid loss. This condition is known as Diabetes Insipidus (DI, meaning “bland urine” in contrast to Diabetes Mellitus, meaning “sweet urine”).
Oxytocin
Released during childbirth to incite uterine contraction. It is also responsible for the Let Down Reflex of milk ejection, which is why breastfeeding can aid in uterine contraction.
Hypersecretion: Oxytocin
Oxytocin toxicity result in an overactive uterus, resulting in hypertrophy. This, in pregnancy, may result in intrauterine growth retardation.
Hyposecretion: Oxytocin
Hyposecretion of oxytocin is rare; this will result in the inability of the uterus to contract (uterine atony) and a defect in milk ejection (due to oxytocin’s role in the let-down reflex).