Ch 46 Flashcards
pituitary gland anterior lobe hormones
growth hormone
TSH
adrenocorticotropic hormone
pituitary gland posterior lobe hormones
ADH
oxytocin
thyroid gland hormones
thyroxine (T4)
triiodothyronine (T3)
growth hormone target? effects there?
a. No specific target gland-Affects body tissue and bone
f. GH acts on newly forming bone> must be administered before epiphyses are fused
h. GH over several years may increase height by 1 foot
drug therapy for growth hormone def
somatropin (Genotropin)
growth hormone route?
c. NOT PO: inactivation by GI enzymes. Given subQ or IM
growth hormone considerations?
e. Can be very expensive: extensive testing before therapy initiated
i. Not appropriate for athletes to build muscle due to extensive side effects
g. Prolonged therapy can antagonize insulin secretion > diabetes mellitus
somatropin (Genotropin)
- Growth hormone used to treat growth failure in children due to pituitary GH deficiency
- Identical amino acid sequence as human growth hormone
drug therapy for growth hormone excess
possibly prolactin release inhibitor bromocriptine
gigantism
excessive growth during childhood (GH excess)
acromegaly
excessive growth after puberty (GH excess)
what are gigantism and acromegaly due to?
both are due to hypersecretion of GH, often caused by tumors.
-if tumor cannot be destroyed by radiation, prolactin-releasing inhibitor, bromocriptine, can inhibit release of GH from the pituitary.
TSH
TRH from hypothalamus>TSH is released>TSH stimulates thyroid to release Thyroxine(T4) and triiodothyronine(T3)
trh from where?
hypothalamus
excess tsh
hyperthyroidism
deficient TSH
hypothyroidism
adrenocorticotropic hormone(ACTH)
CRF(corticotropin releasing factor) stimulates pituitary corticotrophs to secrete ACTH>ACTH stimulates release of glucocorticoids, mineralcorticoids, and androgen from adrenal cortex
glucocorticoids
cortisol
from adrenal cortex
stimulated release by ACTH
mineralcorticoids
aldosterone
from adrenal cortex
stimulated release by ACTH
ACTH pattern
follows diurnal rhythm
i. Cortisol secretion is higher in the early morning, and decreases throughout the day
ii. Stress, and trauma override the diurnal rhythm, and can cause an increase in secretions of ACTH and cortisol
pituitary gland posterior lobe aka
neuro-hypophysis
ADH
promotes water reabsorption from renal tubules to maintain water balance
ADH deficiency causes? can be caused by?
a. large amounts of water to be excreted by the kidneys
i. Can be caused by Diabetes Insipidus (DI), head trauma, brain tumors
1. Fluid and electrolyte imbalance must be closely monitored, and ADH replacement may be needed
vasopressin(Pitressin)
given for DI intranasally, subq, or IV for ADH deficiency
desmopressin(DDAVP)
given for DI for ADH deficiency
ADH excess caused by?
a. Most common cause is small cell carcinoma of the lung
i. Can also be due to medications, other malignancies, and stress
ADH excess causes?
b. Excess amount of water retention causes expansion of the intracellular volume >increased glomerular filtration, and decreased tubular sodium reabsorption > natriuresis (excretion of urinary sodium) > hyponatremia
c. Can cause SIADH (syndrome of inappropriate diuretic hormone)
tolvaptan(Samsca) PT/PD
PT: hyponatremia, SIADH
PD: remove excess fluid, promote natriuresis to balance sodium
tolvaptain(Samsca) NI/PT ed
NI: monitor neurologic status, intake/output, serum sodium
PT ed: take meds at specific intervals as prescribed, get serial labs esp for Na, no grapefruit juice(increases eff of med), careful of fluids (high levels will further hyponatremia, possibly fluid restriction)
thyroxine (T4) and triiodothyronine (T3)
from thyroid gland
regulate protein synthesis and enzyme activity to simulate mitochondrial oxidation
b. Feedback mechanisms regulate T4 and T3 secretion from the thyroid gland
feedback mechanisms to regulate T3/T4
hypothalamus-pituitary thyroid axis(HPT)
c. Hypothalamus releases TRH (thyrotropin-releasing hormone) > stimulates release of TSH from pituitary gland > TSH stimulates synthesis and release of T4 and T3
excess free T4 and T3?
i. Excess free T4 and T3 inhibit HPT axis > decreased TRH and TSH
decreased T4 and T3?
ii. Decreased T4 and T3 will increase the function of the HPT axis
hypothyroidism
decrease in thyroid secretion
-primary or secondary