Term
| what is GH responsible for? |
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Definition
| linear growth and postnatal/prepubescent height. GH is also associated w/alterations in lipid/carbohydrate/nitrogen/mineral metabolism |
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Term
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Definition
| by the somatotroph cells located in the anterior pituitary gland |
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Term
| when are GH levels highest? what pattern is it released in? |
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Definition
| midnight - GH is released in a diurnal, pulsatile pattern |
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Term
| what is the result of excessive GH release? |
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Definition
| excessive GH release = acromegaly, where growth plates enlarge and are unstable/inflammatory |
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Term
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Definition
| IGF-1/insulin-like growth factor 1 is GH-related protein which circulates in the blood as a ternary complex IGFBP-3 and is produced in the liver. IGF-1 is necessary for expression of GH effects. *IGF-1 has a longer half-life than GH*, therefore it may be more representative of the total situation and is tested for along w/GH when looking for a defect such as acromegaly (where IGF-1 levels are persistently high). |
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Term
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Definition
| a condition due to an unusual pituitary tumor which makes GH and is almost always associated with an elevated IGF-1 (very low false positive rate). |
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Term
| what demographics are associated w/acromegaly? |
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Definition
| pts affected are usually in their 20s+ (already reached adult height/epiphysial plates are fused), both genders are equally affected, and these tumors are usually larger by the time symptoms are diagnosed. |
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Term
| what symptoms are associated w/acromegaly? |
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Definition
| enlarged hands/feet, CHF, headaches, coarsening facial features, paresthesias, joint pain, decreased vision, macroglossia, malocclusion (asymmetric jaws), deepening of voice, hypersomnolence, weakness, DM/glucose intolerance and hyperhidrosis |
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Term
| what signs are associated w/acromegaly? |
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Definition
| organomegaly (including heart: HTN), widely spaced teeth, snoring/obstructive sleep apnea, moist/doughy handshake (peripheral edema), skin tags (chondromas), parotid enlargement, visual field defects, tooth marks on tongue, enlarged sinuses/prognathism, carpal tunnel syndrome, proximal myopathy, degenerative osteoarthritis (most disabling symptom), and polyuria/dipsia/phagia |
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Term
| what is the mortality and morbidity associated w/acromegaly due to? |
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Definition
| cardiac, vascular, and respiratory disease (such as DM) most often increase pts' risk of mortality 1-3x |
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Term
| what is therapy for acromegaly? |
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Definition
| normalize GH and IGF-1 levels (biochemical manifestations), which is mainly accomplished via surgery (stereoscopic pituitary hypophysectomy) w/somatostatin (or somatostatin analogues) administered postop. |
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Term
| is the pituitary always the source of excess GH? |
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Definition
| no, the excess GH may be related to releasing factors or the hypothalamus. |
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Term
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Definition
| deficiency of ADH from the posterior pituitary due to tumor/infarct/etc which leads to dilute polyuria (~10-12 L/day). this kind of DM is called central diabetes insipidus (CDI) b/c it occurs in the pituitary. |
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Term
| how is DM insipidus diagnosed? |
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Definition
| ADH levels are hard to obtain, so urinanalysis is usually done in the context of a water deprivation test w/strict observation. an ADH analogue challenge test may also be used. |
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Term
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Definition
| a syndrome involving the pituitary, hyperparathyroidism, and pancreatic islet cell tumor |
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Term
| what characterizes hypopituitarism? how is it diagnosed? |
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Definition
| a pituitary deficient condition which involves multiple pituitary hormones, often first noticed in women w/hyponatremia - then testing for LH/FSH/cortisol is run to dx. |
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Term
| what causes hypopituitarism? |
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Definition
| surgical ablation, radiotherapy, metastatic tumors, sickle cell, DM, and infarction |
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Term
| what is in the ddx for hypopituitarism? |
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Definition
| anorexia, thyroid hypothyroidism, chronic liver disease, hemochromatosis, and myotonia dystrophica |
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Term
| what are symptoms of hypopituitarism? |
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Definition
| frail appearance, catabolic, cachectic, and muscular dystrophy |
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Term
| what is the order of pituitary demise? |
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Definition
| gonadotrophins are affected first, then GH, TSH, and ACTH (the latter are less and less compatible w/life) |
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Term
| what is pan-hypopituitarism? |
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Definition
| hypopituitarism affecting all pituitary hormones. selective hypopituitarism is also possible, with just 1-2 hormones being affected. |
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Term
| what characterizes pituitary infarction? |
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Definition
| pituitary infarction is most commonly associated w/postpartum - however it may occur w/diabetic micro-vascular disease and sickle cell anemia. sheehan's syndrome is the name for when this occurs postpartum and pituitary apoplexy is when it doesn't. pituitary apoplexy usually occurs when pituitary gland hemorrhages affect functionality and may be manifested by sudden shock. |
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Term
| what is pituitary dwarfism? |
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Definition
| impairment of GH secretion, which may present w/a craniopharyngioma on imaging or it may not present w/anything on imaging |
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Term
| what is empty sella syndrome? |
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Definition
| a deformity/lack of the sella floor, often due to an infarction, possibly congenital. this is *mostly innocuous, but is occasionally seen w/hypopituitarism. diagnosed by imaging. |
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