Pituitary and Hypothalamic Dysfunction

Hypothalamus and pituitary gland

Interact to control most metabolic functions of the body

-Hypothalamus controls secretions of the pituitary gland

Anterior pituitary

Creates and secretes hormones

Posterior pituitary

Stores and releases hormones made by the hypothalamus (not an entrepreneur)

Anterior pituitary hormones

Act directly on target tissues

-Prolactin and growth hormone

-APH’s act indirectly by stimulating target tissues to produce other hormones (ACTH, TSH, FSH, LH, MSH)

Corticotropin

APH that stimulates the adrenal cortex to produce corticosteroids, is controlled by a negative feedback system

TSH / thyrotropin

APH that regulates secretion of thyroid hormones, is controlled by a negative feedback mechanism

Negative feedback system hormones

A self-regulating control mechanism where the final product or output of a hormone pathway inhibits its own further production, maintaining homeostasis

Growth hormone

Stimulates growth of body tissues

-Acromegaly: excess of GH-INSULIN RESISTANCE

FSH

One of the gonadotropins, stimulates functions of sex glands beginning at puberty

-Acts on the ovaries or testes

LH

Stimulates production by the gonads of both sex

-Women=ovulation

-Men=testosterone

Prolactin

Plays a part in milk production by nursing mothers

Melanocyte-stimulating hormone (MSH)

Plays a role in skin pigmentation

Antidiuretic Hormone (ADH / Vasopressin)

PPH, functions to regulate water balance

-Secretion=ater reabsorbed in kidneys

-Absence-less water reabsorbed in kidneys and more lost in urine

Oxytocin

PPH, childbirth and lactation

Hypothalamic hormones

Are involved in regulating various bodily functions, including temperature control, hunger, thirst, and emotional responses

-They act by signaling the pituitary gland to release hormones that influence other glands in the body

-CRH , GHRHm TRH, GnRH, Somatostation, PRF / PIF

Corticotropin-Releasign Hormone (CRH / CRH)

Causes release of corticotropin in response to stress and threatening stimuli

-Use CRH in the diagnosis of Cushing’s disease, a disorder characterized by excess cortisol

Hypothalamic hormones cont

-Growth Hormone-Releasing Hormone: Causes release of GH in response to low blood levels of GH

-Somatostatin (growth-inhibiting hormone): inhibits release of GH, found in intestines and the pancreas where it regulates secretion of insulin and glucagon

-Thyrotropin-Releasing hormone: Causes release of TSH in response to stress / exposure to cold, used to diagnose pituitary function and hyperthyroidism

-GnRH: Causes release of FSH and LH

-Prolactin-releasing factor: active during lactation after childbirth

Precocious puberty

-1st type: central precocious puberty: gonadotropin dependent, early ,attraction of hypothalamic-pituitary-gonadal axis, may be caused by genetic variants

-Symptoms: develop secondary sexual characteristics prior to age 9 (males) or 8 (females), accelerated linear bone growth, increased bone age

-2nd type: independent precocious puberty: gonadotropin independent, excess secretion of estrogen and androgen sex hormones in girls-pituitary tumors or estrogen exposure in boys (leydig tumors)

-3rd type: benign or nonprogressive pubertal variants: splatted breast development in girls, acne or Axillary pubic hair in boys

Diabetes Insipidus

Caused by dysfunction in the posterior pituitary lobe and thus absence of ADH

-Excretion of large quantities of dilute urine

-Kidneys filter the water but don’t reabsorbed it

-Circulating fluid volume decreases, producing increased thirst and large amounts of urine production

-Polyuria, excretion of dilute urine, extreme polydipsia, hypernatremia with increased serum osmolarity

Somatropin

Anterior pituitary hormone drug / growth deficiency

-Action: acts like GH, acting on newly forming bone (must be given to children before epiphyses are fused)

-AE’s: mild edema, HA, local muscle pain, weakness, hyperglycemia, otitis media in children, hypersensitivity reaction, intracranial HTN

-Contra: in severe obesity Prader Willi (rx for rt failure), closed epiphyses, active malignancy, caution in diabetes and hypothyroidism

No BBW

Desmopressin acetate

Class-PPH/Antidiuretic

-Action: Synthetic ADH, promotes reabsorption of water in the kidneys

-Use: Helps control diabetes insipidus, bedwetting, and urine disorders

-Ed: monitor input/output, daily weight, serum sodium, renal function, mental statu, fluid overload, monitor for improvement in bleeding / clotting factors

-AE’s headache, nausea, abdominal pain, seizures, confusion, coma, sudden weight gain

-Conras: creatinine cl <50 mL/min

-BBW: Hyponatremia due to too much water retention

Desmopressin acetate interactions

Carbamazepine: Increase Antidiuretic effects w

Alcohol: decrease diuretic effects

SSRI’s / TCA’s: increased risk for hyponatremia

Leuprolide Acetate (Lupron)

Hypothalamic hormones

-Action: inhibits LH and FSH to decrease testosterone and estrogen

-Use: Precocious puberty

-AE’s: pain at injection site, hyperglycemia in DM

-Considerations: May decrease therapeutic effects W Alcohol of antidiabetic drugs = hyperglycemia, assess for decrease in mature sexual characteristics, occur within 2-4 weeks after therapy has begun

-Pt ed: rotate injection sites, FETAL HARM, SC or IM sites, every 4 weeks for dose, may cause pain at site

Octreotide Acetate

Hypothalamic Hormones/somatostatin analog

-Action: suppresses GH and IGF-I release

-Use: acromegaly, carcinoid tumors, vipomas, esophageal variceal bleeding, other hormone-secreting tumors

-AE’s: CNS (dizzy / ha / fatigue), cardiac (Brady / HF), metabolic (hyperglycemia), GI (abd pain/N/cholethiasis), back pain

-Caution: pancreatitis, gallbladder/gallstones, cardiac hx, diabetes / many drug and herb interactions