Term
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Definition
| largest endocrine gland; earliest to appear in development; stores large amount of thyroid hormone (up to 1 months worth); releases T3 & T4; essential for normal neuronal development & bone formation during gestation; primarily controls BMR (basal metabolic rate) |
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Term
| Key Indicators of Abnormal Thyroid Activity/Levels |
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Definition
| unexplained weight gain or weight loss |
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Term
| Thyroid Hormone Synthesis |
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Definition
| 1) Iodide trapping - iodide uptake very efficient in thyroid gland; 2) iodide is then oxidized by thyroid peroxidase; 3) I goes through organification & forms MIT & DIT; 4) MIT & DIT are coupled together to form T3 & T4; 5) endocytosis of MIT- & DIT-containing thyroglobulin followed by lysosomal degradation of MIT & DIT from thyroglobulin; 6) T3 & T4 are secreted |
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Term
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Definition
| daily production: 25 micrograms; half-life: 1 day; potency: 4; >99% bound to thyroxine-binding globulin |
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Term
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Definition
| daily production: 75 micrograms; Half-life: 7 days; Potency: 1 - converted to T3 in effector cells; >99% bound to thyroxine-binding globulin |
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Term
| Effects of TR (thyroid receptor) Activation by T3 |
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Definition
| increases expression of proteins that regulate excitability of a cell: voltage-sensitive Na & Ca channels & Beta-adrenergic receptors --> excitable cells become MORE excitable in presence of thyroid hormone (dangerous: cardiac arrhythmias); increases lipolysis & lipogenesis --> lipolysis & decreased glycogen stores; increase cholesterol production & secretion --> low serum cholesterol |
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Term
| TRH (thyrotropin-releasing hormone) |
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Definition
| environmental stimuli (i.e. cold, acute psychosis, circadian rhythms, severe stress) influence release of this from hypothalamus --> acts on pituitary gland to cause release of TSH |
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Term
| TSH (thyroid-stimulating hormone) |
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Definition
| released from pituitary gland in response to stimulation by TRH; it acts directly on thyroid gland to increase I uptake and T3 & T4 secretion |
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Term
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Definition
| act in negative feedback loop when released by TSH from thyroid gland; reduces both release of TRH from hypothalamus & TSH from pituitary gland |
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Term
| Amount of I needed per day for normal thyroid functioning |
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Definition
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Term
| Example of environmental cues influencing TSH release |
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Definition
| about 30 min after birth, a newborn has a TSH surge due to new, colder environment; essential for proper thermal homeostasis; newly released T3 & T4 activates brown adipose tissue (BAT) that is abundant in newborns; activation of BAT results in large amounts of heat generation |
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Term
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Definition
| congenital hypothyroidism; Signs & Symptoms: lethargy, prolonged postnatal jaundice, protruding abdomen, thick tongue, severe mental retardation, stunted growth; All pregnancies required to be tested for |
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Term
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Definition
| myxedema; S&S's: congestive heart, baggy eyes, facial swelling, non-pitting edema; if untreated, cholesterol elevates --> atherosclerosis or myxedema coma --> death in 60-70% of pts; Mild S&S's: weakness, lethargy, increased weight gain (due to decreased metabolism), depression, & reduced cardiac output |
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Term
| Major Causes of Adult Hypothyroidism |
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Definition
| 1) chronic inadequate I intake with little T3 or T4 produced --> endemic or simple colloid goiter (due to increased TSH release); 2) Pt has adequate I but very little T3 or T4 production --> idiopathic or nontoxic colloid goiter (goitrogens directly inhibit I transport into thryocytes - soy beans, broccoli, cassava root; 3) Hashimoto thyroiditis - autoimmune disorder where Abs produced that target thyroid peroxidase & thryoglobulin - most common cause --> low T3 & T4 but elevated TSH; 4) Postpartum Thyroiditis - after pregnancy, Abs form that damage thyroid tissue, causing release of T3 & T4 resulting in temporary hyperthyroidism --> levels then fall due to tissue damage & decrease in T3 & T4 formation |
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Term
| synthetic T4 - levothyroxine [Synthroid] |
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Definition
| used to treat hypothyroidism; ORAL; half-life: 7 days; MoA: T4 converted to T3 in effector/peripheral tissue; Monitor: TSH & free T4 levels; may need to increase dose for pregnant patients; inexpensive |
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Term
| hyperthyroid disease [Graves Disease] |
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Definition
| S&S's: weight loss (with increased caloric intake), nervousness, restlessness, hot moist skin, heat intolerance, fatigue, weakness, & muscle cramps, exophthalmos (infiltrative opthalmopathy due to periorbital inflammation/extraocular muscle hypertrophy; Clinical symptoms: normal T3 & T4 levels, LOW TSH |
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Term
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Definition
| most common cause of hyperthyroidism; 6x more common in females; characterized by presence of IgG Abs called thyroid stimulating immunoglobulin that mimic TSH & increase T3 & T4 release which supresses TSH to zero eventually leading to "burned out" thyroid gland (hypothyroidism) |
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Term
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Definition
| beta particle emitter that kills tissue; thyroid gland selectively dies off first because it is most efficient, high affinity iodide transporter; no pain, easy to use, no surgical risk; low cancer risk; C/I in nursing mothers; also used to treat thyroid cancer |
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Term
| thionamides - propylthiouracil (PTU), methimazole (Tapazole) |
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Definition
| inhibits thyroid hormone synthesis by inhbiting: iodination rxns & coupling of iodotyrosines; DOES NOT inhibit release of T4 & T3; SEs: minor - drug rash, arthralgia, hepatotoxicity after 3 months; very minor |
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Term
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Definition
| longer half-life than PTU; give once per day; may take a month until T4/T3 are depleted; decrease dose after control of thyroid levels have been achieved; lower risk of agranulcytosis than PTU |
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Term
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Definition
| for severe hyperthryoidism; added effect of blocking conversion of T4 to T3 in peripheral/effector cells by inhibiting type I deiodinase; better for pregnant patients (more highly protein bound) |
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Term
| Iodides [Lugol's solution] |
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Definition
| treatment of hyperthyroidism; MoA: inhibits thyroid hormone synthesis & inhibits release of pre-formed/stored hormone; temporary effects; Lugol's solution is most widely used |
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Term
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Definition
| form of severe hyperthyroidism; medical emergency; caused by trauma, severe infections, thyroid surgery, administration of iodine; S&S's: arrhythmias, delirium, >103 degree F body temp., shock, & coma |
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Term
| Treatment of Thyroid Storm |
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Definition
| 1) stop synthesis of new hormone (thionamides); 2) halt release of stored hormone (iodide - Lugol's solution); 3) block beta-adrenergic receptors (propanolol); 4) inhibit deiodinase (glucocorticoids - dexamethasone, hydrocortisone); 5) antipyretics - APAP, avoid salicylates; less effective if iodide given before thionamides |
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Term
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Definition
| low bone mass resultin in greater probability of bone fractures; fractures occur most commonly on vertebral bodies, distal radius, & proximal femur; probability of fracture increases exponentially with age; |
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Term
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Definition
| due to lack of estrogen post-menopause |
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Term
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Definition
| occurs in men & women who lack adequate Ca intake over life time &/or excess parathyroid hormone activity |
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Term
| Recommended daily Ca for <24 yrs old |
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Definition
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Term
| Recommended daily Ca intake for >25 yrs old |
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Definition
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Term
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Definition
| most important class of drugs in treating osteoporosis; MoA: become incorporated into bone to slow bone turnover by inhibiting pyrophosphatase enzymes in osteoclasts; induces apoptosis in osteoclasts; also used to treat Paget's disease & hypercalcemia of some malignancies |
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Term
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Definition
| amino substituted bisphosphonate; more potent than others; inhibits bone resorption without impairing bone mineralization; also treats Paget's disease - effects lasts for months, good pain reduction; may have vitamin D added to it; increased bone density & reduces fractures; SEs: GI distress, esophageal resosion |
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Term
| Counseling Pts for ALL Bisphosphonates |
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Definition
| take on an empty stomach with a full glass of water; remain seated for 30 min after taking |
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Term
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Definition
| pyridinal bisphosphonate; MoA: binds to hydroxyapetite in bone, decreasing turnover; used in Paget's disease to increase bone density & decrease fractures; SEs: GI distress, esophageal erosion |
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Term
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Definition
| injection of 5 mg/100 mL; treats osteoporosis & Paget's disease; Administration: give 5 mg per IV ONCE A YEAR SLOWLY for more than 15 min |
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Term
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Definition
| IV injection 4 mg/5 mL; treatment for hypercalcemia; repeat treatment after 7 days if Ca levels do not decrease; SEs: osteonecrosis of jaw especially if given multiple doses |
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Term
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Definition
| 150 mg once monthly dose; MoA: similar to other bisphosphonates; SEs: at higher monthly dose: constipation, flu-like symptoms, pain in extremities; Increase in BMD statistically greater in monthly dose than daily dose |
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Term
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Definition
| selective estrogen receptor modulator (SERM) approved for postmenopausal osteoporosis; ADRs: venous thromboembolism; |
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Term
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Definition
| recombinant segment of PTH; treats postmenopausal osteoporosis; Administer SC once daily, very expensive; SEs: nausea, dizziness, leg cramps; appears to work better than alendronate --> greater increase in bone formation in spine & femoral neck |
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Term
| calcitriol (1,25-hydroxyvitamin D) |
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Definition
| most potent vitamin D metabolite; increases Ca absorption & decreases Ca & PO4 ecretion by kidney; used for osteoporosis & hypoparathyroidism; marked reduction in fractures, few side effects, does not depend on liver or kidneys for activation |
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Term
| Non-drug therapies for osteoporosis |
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Definition
| resistance training with Ca supplementation increases BMD |
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Term
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Definition
| Causes: hyperparathyroidism but primarily due to breast & lung cacer where tumors release parathyroid hormone-related protein; S&S's: weakness, lethargy, nausea, polyuria |
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Term
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Definition
| amino substituted bisphosphonate; only in IV form; used for hypercalcemia of malignancy --> reduces bone pain & fractures in multiple myeloma & metastatic breast cancer; occasionally used for Paget's disease; SEs: nausea, anorexia, leukopenia, pain at site of injection, expensive, osteonecrosis of jaw |
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Term
| loop diuretics (furosemide) |
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Definition
| increases renal Ca secretion |
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Term
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Definition
| inhibits dietary Ca absorption |
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Term
| calcitonin - calcimar (Miacalcin), cibacalcin |
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Definition
| secreted from parafollicular cells in thyroid gland; lowers serum Ca by inhibiting osteolysis & increasing Ca excretion by kidney; SEs: generally well-tolerated, Occasional - rash, vomiting, facial flushing; Uses: hypercalcemia, Paget's disease, may be useful in postmenopausal osteoporosis |
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Term
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Definition
| disease with increased bone turnover/abnormal bone formation --> multinucleated osteoclasts that have greater than normal activity; pts have high risk of fractures & bone pain |
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Term
| Treatment for Paget's Disease |
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Definition
| 1) calcitonin 2) zoledronate (Zometa) |
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Term
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Definition
| causes - congenital, autoimmune, surgery; S&S's: hypocalcemia, tetany, seizures; Treatment: calcitriol (1,25-hydroxyvitamin D) |
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Term
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Definition
| Cause - adenoma; S&S's: kidney stones, hypercalciuria, hypercalcemia, reduced BMD, neuromuscular weakness, CNS - drowsiness, reduced alertness, coma; Treatment: surgery in severe cases, MILD - estrogen, oral phosphate, bisphosphonates |
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