Chapter 22: Alterations of Hormonal Regulation
-may fail to function properly
-may respond to inappropriate signals - ✔✔how can feedback systems fail?
-inability to produce or obtain an adequate quantity of required hormone precursors
-inability to convert precursors to the active hormone
-excessive or inadequate hormone production - ✔✔how may an endocrine gland dysfunction?
1. failure of feedback systems
2. dysfunction of an endocrine gland
3. altered hormone
4. ectopic hormone release - ✔✔what leads to too much or too little hormone?
-nonendocrine sites
-autonomous production
-no feedback mechanisms - ✔✔what is ectopic hormone release?
failure of target cell to respond to its hormone (hormone insensitivity) - ✔✔what is target cell
dysfunction?
%
-decrease in number of receptors
-impaired receptor function
-presence of antibodies against specific receptors
-antibodies that mimic hormone action
-unusual expression of receptor function - ✔✔what are receptor-associated disorders?
-inadequate synthesis of a second messenger (cAMP)
-failure of target cell to produce anticipated hormonal response:
-faulty response to hormone-receptor binding:
--failure to generate required second messenger
--abnormal response to second messenger - ✔✔what are intracellular disorders?
hyperfunction & hypofunction - ✔✔what are diseases of the posterior pituitary?
-antidiuretic hormone effects: too much
-examples of diseases: syndrome of inappropriate antidiuretic hormone (SIADH) secretion -
✔✔posterior pituitary disease: hyperfunction?
-ADH level = abnormally high
-causes: ectopic secretion of ADH; post-surgical & with some cancers
-water retention: ADH action on renal collecting ducts increases their permeability to water
-normal renal, adrenal, & thyroid function must exist w/ high ADH level - ✔✔syndrome of
inappropriate antidiuretic hormone (SIADH) secretion
CM & Dx:
-hyponatremia: sodium <135 mEq/L
-hypoosmolality: <280 mOsm/kg
-urine hyperosmolality
-hypervolemia
-weight gain
-serum sodium levels < 110-115 mEq/L (severe & sometimes irreversible neurologic damage)
Tx:
-correction of underlying caudal problems
-administration of hypertonic saline
-vaptans
%
-fluid retention between 800-1000 mL/day
-resistant or chronic SIADH: demeclocycline - ✔✔SIADH: CM, Dx, Tx
-insufficiency of ADH
-polyuria & polydipsia
-partial or total inability to concentrate urine
-inability of kidney to increase permeability to water:
--excretion of large volumes of dilute urine
--increase in plasma osmolality
--urine output: 8-12 L/day (normal output = 1-2 L/day) - ✔✔diabetes insipidus
1. neurogenic = insufficient amounts of ADH
2. nephrogenic = insensitivity of renal collecting tubules to ADH
3. dipsogenic = excessive fluid intake, lowering plasma osmolarity to point that it falls below threshold
for ADH secretion - ✔✔what are the types of diabetes insipidus?
Tx:
1. neurogenic: administration of synthetic vasopressin analog desmopressin acetate (DDAVO)
2. nephrogenic:
-tx of any reversible underlying disorders
-discontinuation of etiologic medications
-correction of associated electrolyte disorders
-administration of thiazide diuretic agents
3. dipsogenic: effective management of water ingestion - ✔✔diabetes insipidus: CM, Dx, Tx
hyperfunction and hypofunction - ✔✔what are diseases of the anterior pituitary?
hormone effectors:
-hyperpituitarism
-hypersecretion of GH
-hypersecretion of prolactin
%
-absence of selective pituitary hormones or complete failure of all pituitary hormone functions
-pituitary is vascular & therefore vulnerable to ischemia & infarction - ✔✔anterior pituitary:
hypopituitarism
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