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34 Cards in this Set
- Front
- Back
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Tests specific for thyroid status or function can be categorized into what 4 categories?
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1-measure the concentration of products secreted by thyroid
2-evaluate the integrity of the hypothalmic pituitary thyroid axis 3-assess inherent thyroid gland function 4-detect antibodies to thyroid tissue |
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Tests the directly or indirectly measure the concentration of thyroxine (T4) and triiodothyronine (T3) include what?
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-Free T4
-Total serum T4 -Serum T3 resin uptake -Free T4 index -Total serum T3 |
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What is the primary test to detect thyroid dysfunction?
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TSH
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It is the current recommendation that all lab assays use what generation functional sensitivity for TSH now?
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3rd generation
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What is the normal range of TSH?
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0.4-5.0
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What is the upper limit of TSH?
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4.5-5.5
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TSH levles below what are generally diagnostic of hyperthyroidism?
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below 0.5
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Levels above what are consistent with hypothyroidism?
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above 20
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Levels of TSH over what are associated with increased risk of developing overt hypothyroidism?
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over 2.5
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Elevated levels of TSH in association with normal T4 levels indicate what?
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sub acute or subclinical hypothyroidism
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Free T4 measures what?
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unbound T4 in the serum
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Free T4 is the most accurate reflection of what?
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thyrometabolic status
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Free T4 makes up what percent of total T4?
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less than 1%
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Total serum T4 measures what?
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both bound and free T4
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Total serum T4 is influenced by what?
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any alteration in the concentration or binding affinity of thyroid-binding globulin
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An increased serum T4 may indicate what diseases?
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-hyperthyroidism
-elevated concentrations of thyroid-binding proteins -nonthyroid disease |
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Total serum T4 elevations have been noted in who?
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elderly with relatively minor illness
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What percent of pts admitted to psychiatric hospitals ahve transient total serum T4 elevations?
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20%
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Decreased total serum T4 may indicate what diseases?
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-hypothyroidism
-decreased concentrations of thyroid-binding proteins -nonthyroid illness |
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What are some other things that have been associated with low total serum T4?
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-neoplastic disease
-DM -burns -trauma -liver disease -renal failure -prolonged infections -cardio disease |
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Some drugs cause alterations in total serum T4 because they compete for what?
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they compete for protein binding with T4
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PTU and mehtimazole work how?
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they inhibit peroxidases in the thyroid from iodinating T4
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Serum T3 resin uptake indirectly estimates what?
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the number of binding sites on thyroid-binding perotien occupied by T3
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Total serum T3 is usually measured as an indicator for what?
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hyperthyrodism
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Like T4, T3 is also mainly protein bound, so what will alter measurement?
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change in thyroid-binding protein concentration
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How does Furosemide and ASA affect thyroid hormone binding?
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it displaces T4, but the effect is short lived
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Furosemide and ASA does what to Total T3/T4?
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decreases it
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What does Furosemide and ASA do to Free T3/T4?
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-increase by ultrafiltration
-decreased is assay with marked dilution |
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How does Phenytoin and CBZ affect thyroid hormone binding?
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-decreases binding and causes a decreased TSH response
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Phenytoin and CBZ do what to total T3/T4?
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decreases it
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Phenytoin and CBZ does what to Free T3/T4?
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-decrease in most assys long term
-may increase short term -normal by ultrafiltration |
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Heparin does what to thyroid hormone binding?
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-activated lipoprotein lipase, releasing free fatty acids frm triglycerides
---Yeah, I don't understand it either, but Lopes had in on his paper, so what ever------ |
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What does Heparin do to Total T3/T4?
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nothing
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What does Heparin do to Free T3/T4?
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-increases it
-degree of increase rises with time of storage, accentuated with high triglycerides |
