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Endocrine
Pathophys
37
Physiology
Undergraduate 1
05/07/2010

Additional Physiology Flashcards

 


 

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Term
What are the three categories of endocrine diseases?
Definition

Hyposecretion

 

Hypersecretion

 

Hyporesponsives

Term
What are the two classsifications of endocrine disorders?
Definition

n  Primary:  direct malfunction of hormone producing gland

n  Secondary:  malfunciton of the hypothalamus/pituitary cells that control the hormone producing gland

n  Measurement of of pituitary and endocrine gland hormones allows differentiation between primary and secondary endocrine failure.

In primary you see a low levels of hormone but high levels of trophic pituitary hormone and in secondary there is a decrease in both types.

Term

What do you know about hyposecretion?

Definition

n  Primary hyposecretion:  When an endocrine organ releases an inadequate amount of hormone to meet physiologic needs.

n  Secondary hyposecretion:  secretion of tropic hormone (such as TSH) is inadequate to cause thyroid gland to secrete adequate amounts of thyroid hormone

Term
What do you know about Hypersecretion?
Definition

Primary:  endocrine gland secretes an abnormally high amount of hormone (in this case the TSH will remain low)

Secondary:  caused by increased secretions caused by either a tropic hormone (ie TSH) or by hormone secretion from an ectopic source (as sometimes occurs in malignancies)

Term
What do you know about hyporesponsiveness?
Definition

n  This is hormone resistance of the target organ and causes the same signs and symptoms as hyposecretion.

n  The usual cause is lack of or deficiency of receptors. 

n  In this case, plasma hormone levels may be high, even though showing signs of hyposecretion.

Term
What is a functional endocrine disorder?
Definition

n  Caused by nonendocrine disease such as cronic renal failure,liver disease, or heart failure.  n  Dysfunction may arise if end organ fails to respond to hormones

n  Presence of normal hormone levels w/out norm  action indicates hormone resistance

n  May be genetic or acquired and may include defects at receptor sites, antibody reaction to hormone receptors, and defective post receptor hormone action.

Term
What are some other causes of endocrine diseases?
Definition

n  May be an inborn error of metabolism.  Can include excessive production of hormone precursors due to an enzymatic block in the synthetic pathway, and enzyme deficiencies that impair hormone synthesis. n  Also nonendocrine tissue can produce hormones such as malignant tumors

n  Some disorders may be induced by medical treatments.  These iatrogenic disorders can be caused by chemotherapy, radiation therapy, or surgical removal of glands

Term
What regulates ADH release?
Definition

n  Osmotic pressure of plasma (tracked by osmoreceptors in hypothalamus)

n  When body fluids become too concentrated ADH is released leading to incr reabsorption of water in the kidneys

n  In presence of ADH permeability of renal collecting ducts and tubules to water increases greatly and allows most H2O to be reabsorbed

Term
Etiology of Diabetes Insipidus
Definition

n  ADH deficiency

n  Damage to ADH producing cells in hypothalamus can occur w/ closed head trauma, intracranial tumors, and neurosurgery.  Some pharmocologic agents can do this, too.

Term
What occurs in Diabetes Insipidus?
Definition

n  Damage to posterior pituitary.  Which may be temp or perm n  Large diuresis of very dilute urine resulting in large volume excretion of hypotonic water n  30% idiopathic, 20% caused by surgical removal of brain tumor, 16%  result from nonsurg brain trauma, and 25% are secondary to brain tumors, while 9% follow a hypophysectomy n  Because free water is lost it causes hyperosmolality  n  Central DI is caused when lack of ADH is produced while nephrogenic DI occurs in chronic renal disease and results from renal tubules being less responsive to ADH

Term
Clinical manifestations of DI?
Definition

n  Polyuria and polydipsia (hallmark signs n  Symptoms persist at night and interrupt norm sleep patterns n  Dry mucous membranes n  Poor skin turgor  n  Decr saliva and sweat

n  If thirst center damaged then DI become life threatening illness because incr losses by kidney does not trigger thirst center!

n  DI results in hypernatremia thus s/s similar to dehydration, also hypotonic polyuria, and hypertonicity

Term
Treatment for DI?
Definition

Daily replacement of ADH

Free access to fluids

Home testing of urine specific gravity

Term
Etiology of ADH excess?
Definition

n  Syndrome of inappropriate ADH excretion

n  Ectopic production of ADH has been noted in association w/ several types of tumors (most common lung malignancy but non malig lung disorders also can synthesize ADH), drug induced ADH occurs w/ such meds as morphine and barbiturates.

n  Causes hyponatremia

Term
Clinical manifestations of SIADH?
Definition

n  Due to hypotonicity it is characterized by hyponatremia

n  Urine osmolality is very hgih

n  Serum osmolality is low

n  Weakness

n  Muscle cramps

n  Poor skin turgor

n  Fatigue

n  Anorexia

n  Lethargy

n  Nausea and vomiting

n  Postural bp changes

n  In severe cases:

n  Confusion

n  Hemiparesis

n  Seizures

n  Coma

n  Lab findings: 

n  Low serum sodium

n  Low hematocrit

n  Low BUN levles

 

Term
Treatment for SIADH?
Definition

n  Fluid restriction n  IV admin of saline combined w/ furosemide may cause loss of free water

n  Hyponatremia should be corrected slowly n  Can use meds to block ADH 

n  Lithium can be given because blocks affects of ADH in kidneys...low therapeutic level   n  Demetrocycline (antibiotic):  blocks affect of ADH in the kidney....super infections

Term
What are the actions of the thyroid hormone?
Definition

n  Thyroid is in neck region and secretes thyroxine and triodothyronine    n  Secretion of TH regulated by hypothalamic-pituatary-thyroid feedback system

n  Effect of system to maintain appropriate concentration of free thyroid hormones   n  Amount of TH released controlled by TSH release   n  TSH regulated by thyrotropin releasing hormone from hypothalamus

n  Ths influences metabolic rate

Term
Etiology of hypothyroidism?
Definition

       congenital or acquiredn  Most cases are primary due to direct dysfx of thyroid glandn  Congen hypo may result from:  thyroid dysgenesis (most common), blocking of TSH receptors and defective synthesis of THn  Most common cause of acq is lymphocytic thyroiditis, also caused by irradiation of T gland, iodine deficiency, food w/substances that interfere w/TH synthesis, also some drugs like lithiumn  2nd hypo is caused by defects in TSH production and occurs in those w/ severe head trauma, cranial neoplasms, brain infxn, cranial irradiation, an neurosurgery

Term

Clinical mainifestations of

 

Hypothyroidism VS. Hyperthyroidism?

Definition

Hyperthyroidism

Hypothyroidism

sleeplessness, nervousness,Musc weakness, fatigueSusceptibility to infxn, Warm, silky, damp skin, Heat intolerance, Incr appetite w/ weight loss, Incr gastric motility, Tachycardia,vNarrow pulse pressure, palpitations, angina, Dyspnea, Goiter, Silky hair, Eye:  burning, tearing, diplopia, lid lag, prom eyes, stare eyelid tremors Absence of forehead wrinkling w/ upper gaze,Decr or asent menses,hyperreflexia

Lethargy, Weakness, Dry, pale, cool, coarse skin, Cold intolerance, Weight gain, Constipation, Bradycardia, wide pulse pressure, Dyspnea, chest pain, Thyroid shows diffuse enlargement or is not palpable, Hair coarse, Sluggish return of reflexes; mental impairment; poor mem, depressed affect; deafness,Facial edema,Heavey prolonged menses, infertility

Term
Treatment of Hypothyroidism
Definition

n  Goal is to return to euthyroid state

n  Given oral thyroid hormone (levothyroxine)

n  Must be not be given too quickly or pt may experience insomnia, anxiety, and mood lability

Term
Etiology of hyperthyroidism
Definition

n    Thyroid follicular cell hyperfunction w/ synthesis of THn    Caused by stim of TSH receptors by substances like TSH or TSH receptor antibodiesn    Autonomous hyperfunction can be caused by adenomas and (rarely) thyroid carcinoman    Stim of TSH receptors by TRAb leads to diffuse toxic goiter (graves disease):  most common cause of hyperthyroidism.  Mediated through autoimmune process.  More common in womenn    Thyroid follicular destruction w/ realse of THn    Ingestion of excessive TH or iodide prepsn    Incr levels incr metabolic rate

 

 

 

Term
Treatment of hyperthyroidism
Definition

n    TH production decreased w/ class of antithyroid drugs called thionamides

n    Radioactive iodine treatment to ablate the gland (but must watch for hypothyroidism)

n    Surgical removal of T gland (rarely practiced) (can lead to hyperparathyroidism)

 

Term
What is the parathryoid hormone all about
Definition

Helps maintain homeostasis thru  regulation of ca+ concentrations in the bloodn    PTH acts on bones and renal tubules and incr serum levels of calciumn    In bone PTH incr osteoclastic activity resulting in release of calcium to ECFn    Incr reabsorption of ca+n    Stims activation of V-D which incr intestinal ca+ absorptionn    Serum ca+ provide feedcback to reg PTH:  decr in ca causes release of PTHn    Calcitonin (produced by thyroid parafollicular cells) also influences ca in bone cellsn    It incr bone formation by osteoblasts thus inhibiting breakdown by osteoclasts:  it tends to decr calcium blood levles and promote conservation of bone

Term
Etiology of hyperparathyroidism
Definition

n  Genetics

n  Malignant tumors may release PTH

n  During pregnancy can lead to neonatal complications

n  In chronic renal failure:  secondary hyperparathyroidism may result from abnormal levels of phosphate and calcium

Term

 

 

Clinical manifestations of hyperparathyroidism

Definition

 

 

 n  Related to level of hypercalcemia n  May present asymptomatic hypercalcemia but are prone to kidney stones and osteoporosis n  Other include:  polyuria n  Dehydration n  anorexia/nausea/vomitting/constipation n  Bradycardia n  Heart block n  Cardiac arrest

Term

 

 

Treatment of Hyperparathyroidism

Definition

n  Surg removal of parathyroid is treatment of choice

n  Hydration (to prevent kidney stones)

n  Ambulation

n  Alendronate (may prevent bone loss)

Term

 

 

 

Etiology of Hypoparathyroidism

Definition

 

nFrequently occurs as consequence of parathyroid or thyroid surgery and may be temp or perm
nCongenital lack of parathyroid tissue
Term

 

 

 

Clinical manifestations of Hypoparathyroidism

Definition

n  Result of low serum calcium

n  Circumoral numbness

n  Paresthesias

n  Musc cramps

n  Fatigue

n  Hyperirritability

n  Anxiety

n  Depression

n  Intracranial pressure

n  Carpopedal spasm

n  Laryngospasm

n  Neuromusc irritability

n  Tetany

n  Chvosteck sign

n  Trousseau sign

Term

 

 

 

 

Treatment of Hyperparathyroidism

Definition

 

nIV calcium if acutely hypocalcemic
nCalcitriol should be given in emergent phase
nLong term includes:
nOral calcium supplement and V-D
Term

 

 

 

 

Which hormones are adrencorticals?

Definition

 

nSteroids including: 

nGlucocorticoids:  primary effect on glucose metabolism, they are antiinsulin hormones and raise blood sugar making it available
nmineralcorticoids (aldosterone):  maintain norm salt and water balance
n sex steroids (androgenic):  role in devel and maintenance of secondary sex characteristics

 

Term

 

 

 

 

Etiology of Adrenocortical Insufficiency

Definition

n    Primary is Addison disease:  caused by disease of adrenal cortex

n    Also from inadequate secretion of ACTH from anterior pituitary n    Also lack of CRH secretion from hypthalamus

n    Syndrome:  congenital adrenal hyperplasia:  is a rare cause of adrenal insufficiency in peds:  due to enzymatic defects in biosynthesis of cortisol by the adrenal

n    Severe and life threatening symptoms occur due to lack of circulating cortisol

Term

What is specfic cause of primary adrenal insuffcienc(addison disease)

ease)

Definition

 

nDestructin of adrenal gland through idiopathic or autoimmune mechanisms, TB, trauma, or hemorrhage of adrenals, fungle disease, and neoplasia.
Term

 

 

 

 

Specific cause of secondary adrenal insufficiency

Definition

 nUsually iatrogenic in origin because of large number of patients receiving corticosteroid therapy for chron illness

nProlonged exposure to pharm doses of exogenous corticosteroids supresses ACTH and CRH stim of the adrenal gland through neg feedback.  If cortico admin suddenly halted or if pt has sudden stress induced incr in cortisol the adrenal gland will be unable to respond by incr cortisol secretion
Term

 

 

Clinical manifestations of adrenocortical insufficiency?

Definition

Early signs

If untreated

Anorexia, Wt loss, Salt craving, Apathy Weakness,Malaise, Eletrolyte imbalance Hyperpigmentation of skin

n/v/d,Dehydration

Hypotensive or tachycardic

Sudden onset of n/v anorexia and hypo-tension suggests acute adrenal insufficiency and is med emergency

Term

 

 

 

 

Treatment of Adrenocortical insufficiency

Definition

 

 

Replacing absent or deficient hormones

Term

 

 

 

Etiology of hypercortisolism

Definition

 

nhyperfunction of a portin of hypothalamic pituitary adrenal axis
nPrimary caused by disease of adrenal cortex and secondary caused by hyperfunctino of anterior pituitaryACTH secreting cells
nCushing syndrome used to describe clinical features of hypercortisolism
nCushing disease is diagnosis reserved for pituitary dependent conditions
Term

 

  

Clinical manifestations of hypercortisolism

Definition

n  Round face w/ prom flushed cheecks n  Noticeable weight gain n  Incr total body fat especially in abdomen n  Cervical fat ad n  Capillary friability n  Thinning of skin w/ formation of purple striae & ecchymoses over abs, arms and thighsn  Hypertension may develop n  W/ chron cushing diseae:  Demineralization of bones/fracturesemotinal changes:  depression emotional liability, anxiety irritability, rarely euphoria n  Decr in short term mem, concentration, attention span n decr Muscle mass n  Muscle weakness

Term

 

Treatment for Hypercortisolism

Definition

nTransphenoidoal hypophysectomy

nUnilateral adrenalectomy
nRadiation therapy
nChemotherapeutic agents
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