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38 Cards in this Set
- Front
- Back
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How does thyroid hormone increase cardiac output
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1. increases HR via increased density of B1-adrenergic receptors
2. increased contractility due to increased phospholamban along with increased B1 receptor density |
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what mediates decreased peripheral resistance in thryotoxicosis
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increased production of CO2 by the tissue
increased production of NO by vascular endothelium |
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what is the (A-V)O2 difference in thryotoxicosis
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smaller than normal due to AV shunting, more venous O2 than normal
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what two extra heart sounds are hear during thryotoxicosis
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midsystolic ejection murmur due to hyperdynamic state of LV
scratchy systolic sound due to rubbing of pericardial surface |
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what causes the hyperdynamic apical impulse in thyrotoxicosis
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concentric ventricular hypertrophy due to excess thyroid hormone stimulating transcription of sarcomere proteins
*also leads to diastolic dysfunction because less compliant |
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differentiate serum cholesterol concentration in hypo/hyperthryoidism
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hyperthryoid - increased density of hepatic LDL receptors leads to abnormally low levels of cholesterol
hypothryoid - reduced secretion of cholesterol in bile as well as decreased LDL receptors leads to hypercholesterolemia |
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what are the serum levels of: Ca, PTH, and alkaline phosphatase in thryotoxicosis
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increased serum Ca
increased serum alkaline phosphatase decreased serum PTH |
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differentiate the endometrium in hypo vs. hyperthyroidism in women
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hyper - low estrogen levels inhibits endometrial build-up
hypo - low progesterone levels causes endometrial hyperplasia |
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differentiate the causes of failure to ovulate in hypo vs. hyperthryoidism
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hyperthyroid - decreased mid-cycle LH surge because of low estrogen levels (normal LH and FSH serum levels)
hypothyroid - decreased progesterone due to decreased LH leading to endometrial hyperplasia, maybe hyperprolactinemia due to no thryoid hormone inhibition of prolactin secretion |
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what causes decreased contractility in hypothryoidism
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increased deposition of mucopolysaccharides between myocardial fibers along with myocardial fiber loss
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most common cause of an enlarged heart in hypothyroidism
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pericardial effusion
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differentiate the circulating thyroid hormone levels and radioactive iodine uptake in subacute thyroiditis right after infection vs. several months later
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post-infection - increased circulating T4 and T3 with decreased RAIU
months later - normal T4, T3, and RAIU |
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three causes of hyperthryoidism with decreased RAIU
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1. post-infectious thyroiditis
2. postpartum thyroiditis 3. amiodarone-induced thyroiditis |
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4 causes for increased level of total T4 and TBG with normal levels of free T4 and TSH
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1. pregnancy
2. supplemental estrogen 3. tamoxifen 4. acute viral hepatitis |
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what is the best initial screening test for both hyperthyroidism or hypothyroidism
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TSH level
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differentiate the T3, T4, and TSH in Grave's vs. Hashimoto's thyroiditis
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Grave's - increased T4 and T3 with decreased TSH
Hashimoto's - decreased T4 and T3 with increased TSH |
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three physical exam findings that occur exclusively in Grave's but no other type of hyperthyroidism
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1. infiltrative ophthalmopathy
2. finger clubbing 3. pretibial myxedema (non-pitting plaques or nodules) |
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two features that differentiate myxedema coma from hypovolemic shock
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1. bradycardia
2. hypothermia < 94 degrees |
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why do patients with hypothryoidism develop hyponatremia
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patients are unable to dilute their urine appopriately and develop isovolemic hyponatremia
*total body water is increased but plasma volume is decreased (lose more salt than water) |
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what enzyme does IL-6 block
what are it's actions |
5-deiodinase:
convert T4 --> T3 and rT3 --> T2 |
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what is diagnostic of nonthyroidal illness syndrome
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low T3 with elevated rT3
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why does serum T4 decrease in nonthyroidal illness syndrome
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TSH is depressed due to IL-1B and TNF-a
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what is usually administered to patients for hemodynamic support during nonthyroidal illness syndrome that will further decrease TSH and T4 levels
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high doses of glucocorticoids or dopamine
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what causes nonthyroidal illness syndrome
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septic shock increases the inflammatory cytokines IL-6
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what are lid lag and lid retraction associated with
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hyperthyroidism
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how does thyroid hormone cause heat intolerance
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uncouples mitochondrial electron transport from ATP synthesis
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why are AST, ALT, y-GTP, and bilirubin mildly elevated in hyperthyroidism
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AV oxygen difference across the splanchnic bed increases, due to hyperdefection, leading to hepatocellular hypoxia
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why do patients with hyperthyroidism have an increased sensitivity to warfarin
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accelerated clearance of vitamin K dependent clotting factors
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two medications that decrease the peripheral conversion of T4 --> T3
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propranolol
amiodarone |
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TSH levels < 0.1 that indicate something other than hyperthyroidism
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pituitary destruction
high-dose glucocorticoid or dopamine supplementation elevated hCG |
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what causes non-pitting myxedema in hypothyroidism
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increased capillary permeability and decreased lymphatic flow lead to chronic fluid collection in the interstitium which causes mast cells to release hyaluronic acid
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why is carpal tunnel syndrome commonly seen in hypothyroidism
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glycosaminoglycan deposits and edema form around peripheral nerves causing compression neuropathies
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what cause prolonged relaxation time of the deep tendon reflexes in hypothyroidism
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decreased calcium uptake by skeletal muscle sarcoplasmic reticulum (decreased phospholamban)
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associated with normochromic, normocytic anemia
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hypothyroidism due to decreased erythropoietin production
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medications that may precipitate hypothyroidism
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lithium
amiodarone dietary iodide deficiency |
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what causes decreased TBG
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increased androgens
nephrotic syndrome high-dose aspirin, NSAIDs, phenytoin |
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what antibodies are present in > 90% of patients with autoimmune hypothyroidism
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thyroid peroxidase antibodies
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the presence of amenorrhea and breast atrophy suggests what as the cause for hypothryoidism
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hypotiuitarism - low TSH and T4
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