Adrenal, Pituitary, GH 8.23 Flashcards
Cushing’s Syndrome
Increased glucocorticoid activity in the blood 1. Exogenous - glucocorticoid therapy 2. Endogenous - excess cortisol from the adrenal gland Sx include: moon face, red cheeks, excessive weight gain in abdomen, striae, depression
Sub-types of Cushing’s
ACTH Dependent Pituitary tumor making ACTH Ectopic tumor making ACTH ACTH Independent Adrenal tumor making cortisol in the absence of ACTH
Two thyroid hormones
T3: 3 Iodines, less produced, more potent, long half life (around 1 day) T4: 4 Iodines, more produced, less potent, long half life (around 6 days)
Effect of Thyroid Hormones
Increase metabolism Increase cardiovascular output/rates Contribute to growth Many other systems…
Thyroid Hormone Feedback Loop
Disease of too little thyroid hormone
Too little – hypothyroidism
– 1o – low fT4; high TSH (e.g. Hashimoto’s thyroiditis) (goiter symptoms)
– 2o – low fT4; TSH not elevated (hypopit) (atrophied thyroid)
Disease of too much thyroid hormone
Too much – hyperthyroidism
– Almost always 1o hyperthyroidism
– TSH-secreting tumors (secondary hyperthyroidism) are VERY rare
– High fT4; low TSH (e.g. Graves’ disease)
Stimulants of GH
Amino Acids
Hypoglycemia
Exercise
Stage 3/4 Sleep
Gonadal Steroids/thyroid hormone
Inhibitors of GH
Glucose
GH
IGF-1
Cortisol
Feedback loop of GH
Diseases of too much GH
Too much – almost always due to pituitary GH-secreting tumor.
– Before puberty – gigantism
– After puberty – acromegaly
Diseases of too little GH
Too little – Growth hormone deficiency
– Children – short stature
– Adults – controversial
Screening test for GH excess
Test for IGF1
Tx for GH excess
Surgery
Screening for low GH
Stimulation tests with Arg, or sleep study
