MAZI
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you want to treat hypothyroidism because of complication of radioactivve iodin treatment in graves disease (3 months after diagnosis) , for dose adjusting and monitoring of levothyroxine you order: 1. TSH 2.free T4 3.free T3 4.no need for monitoring
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| MAZI
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excuse me
1.TSH
2.freeT4
3.free T3
4.no need for monitoring
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| achilles
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1-TSH ?
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| MAZI
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| MAZI
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excuse me achilles
whats your explanation?
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| achilles
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follow up of treatment of thyroid disorders is done based on the TSH levels.
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| MAZI
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even after previos thyrotoxicosis?
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| achilles
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i think it should be. pt had thyrotoxicosis but now the pt has iatrogenic hypothyroidism. TSH is used for monitoring the Rx of thyroid disorders so thats why i choose TSH. lets also wait for others to add something to this.
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| AAAAA
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1TSH
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| AAAAA
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Lab tests performed in diagnosing and monitoring primary hypothyroidism are serum TSH and Free Thyroxine Index (FT4I)6. The first step in evaluation is to measure serum TSH and free T4 index or serum free T42. Overt primary hypothyroidism reveals a rise in TSH and free serum T4 level is low2. If the serum free T4 is low and the TSH is normal or low then diagnosis of central hypothyroidism or nonthyroidal disease can be made2. Additional tests might include free T4, thyroid autoantibodies such as antithyroglobulin autoantibodies and anti-thyroid peroxidase, and in the case of suspicious thyroid structure then a thyroid scan and/or ultrasonography5. Less common but very important tests also include total T3 and free T3 as TSH is often normal indicating euthyroid despite adequate T3 levels which could be indicative of Wilson’s Syndrome
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| MAZI
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because of thyrotoxicosis, the level effect of thyroid hormone on the level of TSH is impaired, and it take several months to become normal, in the primary hypothyroidism this effect is normal and you can take the TSH level to monitoring but after hypothyroidism due to treatment of thyrotoxicosis( graves) the best parameter for monitoring the treatment is T4 level
the correct answer is 2. T4 LEVEL
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| achilles
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thanks so much mazi. i did not know this. wonderful ! thanks. now i wont forget this
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| achilles
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yes this was a very good point
there is always so much that we dont know yet(thats the way medicine is, makes you humble. just when you think you know it all it will throw at you somehing that you have no idea of) and thanks to people like yu on the forum i keep learning something new everyday.
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| cyra
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Good stuff MAZI!Thanks!
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| infliximab
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MAKES SENSE
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| AAAAA
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In the elderly and those with coronary heart disease, a starting dose of 25 micrograms levothyroxine (thyroxine) daily is recommended; the dose is then increased by 25 micrograms after 4 weeks [ABPI Medicines Compendium, 2004]. After the individual has been taking 50 micrograms daily for 6 weeks,
recheck thyroid-stimulating hormone (TSH) and titrate by 25 micrograms every 6 weeks until the TSH level is in the normal range
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| AAAAA
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Thyrotropin/Thyroid Stimulating Hormone (TSH)
For more than twenty-five years, TSH methods have been able to detect the TSH elevations that are characteristic of primary hypothyroidism. Modern-day TSH methods however, with their enhanced sensitivity are also capable of detecting the low TSH values typical of hyperthyroidism. These new methods are often based on non-isotopic immunometric assay (IMA) principles and are available on a variety of automated immunoasssay analyzer platforms. Most of the current methods are capable of achieving a functional sensitivity of 0.02mIU/L or less, which is a necessary detection limit for the full range of TSH values observed between hypo- and hyperthyroidism. With this level of sensitivity, it is possible to distinguish the profound TSH suppression typical of severe Graves’ thyrotoxicosis (TSH < 0.01 mIU/L) from the TSH suppression (0.01 – 0.1 mIU/L) observed with mild (subclinical) hyperthyroidism and some patients with a non-thyroidal illness (NTI).
In the last decade the diagnostic strategy for using TSH measurements has changed as a result of the sensitivity improvements in these assays. It is now recognized that the TSH measurement is a more sensitive test than FT4 test for detecting both hypo- and hyperthyroidism. As a result, some countries now promote a TSH-first strategy for diagnosing thyroid dysfunction in ambulatory patients (provided that the TSH method has a functional sensitivity ≤ 0.02 mIU/L). Other countries still favor the TSH + FT4 panel approach, because the TSH-first strategy can miss patients with central hypothyroidism [Section 3C(d)vi] or TSH-secreting pituitary tumors [Section 3C(d)vii] (18,189-191). An additional disadvantage of the TSH-centered strategy is that the TSH-FT4 relationship cannot be used as a “sanity check” for interferences or unusual conditions characterized by a discordance in the ratio of TSH/FT4 (Table 1).
(a) Specificity
TSH is a heterogeneous molecule and there are different TSH isoforms found in blood as well as in pituitary extracts used for assay standardization (Medical Research Council (MRC) 80/558). In the future, recombinant human TSH (rhTSH) preparations might be used as primary standards for standardizing TSH immunoassays (190). Current TSH IMA methods use TSH monoclonal antibodies that virtually eliminate cross-reactivity with other glycoprotein hormones. These methods however, may detect differences in epitope recognition with abnormal TSH isoforms secreted by some euthyroid individuals, as well as some patients with abnormal pituitary disease conditions. For example, patients with central hypothyroidism caused by pituitary or hypothalamic dysfunction, secrete TSH isoforms with abnormal amounts of glycosylation and reduced biological activity. These isoforms are measured as paradoxically normal or even elevated serum TSH concentrations by most methods (189,191,192,194). Likewise, paradoxically normal serum TSH levels may be seen in patients with hyperthyroidism due to a TSH-secreting pituitary tumor, that appears to secrete TSH isoforms with enhanced biologic activity (190,195,196).
Sensitivity and/or specificity problems with a TSH IMA method typically results in falsely high rather than falsely low TSH values (197). This is because inadequate washing or the presence of an interfering substance results in a high background or false bridge between the capture and signal antibodies. This creates a high signal on the solid support which is read out as a falsely high result (115). The erroneous value may not necessarily be in the abnormal range but may be an inappropriately normal value in a hyperthyroid patient (197). In vitro heparin contamination of the specimen can result in erroneously low serum TSH values, whereas insensitivity or the presence of heterophilic antibodies (HAMA) are the most common cause of erroneously high serum TSH results (115,197). It should be noted that since antibodies cross the placenta, HAMA has the potential to influence a neonatal screening test result.
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| AAAAA
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TSH is still the GOLD standard for monitoring and dose adjusting for hypothyroidism secondary due to complication of Grave'es Disease !
It is now recognized that the TSH measurement is a more sensitive test than FT4 test for detecting both hypo- and hyperthyroidism. As a result, some countries now promote a TSH-first strategy for diagnosing thyroid dysfunction in ambulatory patients (provided that the TSH method has a functional sensitivity ≤ 0.02 mIU/L). Other countries still favor the TSH + FT4 panel approach, because the TSH-first strategy can miss patients with central hypothyroidism [Section 3C(d)vi] or TSH-secreting pituitary tumors [Section 3C(d)vii] (18,189-191). An additional disadvantage of the TSH-centered strategy is that the TSH-FT4 relationship cannot be used as a “sanity check” for interferences or unusual conditions characterized by a discordance in the ratio of TSH/FT4 (Table 1).
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| AAAAA
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TSH is still the right answer !!!!!!!!!!!!!!!!!
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MAZI wrote:
because of thyrotoxicosis, the level effect of thyroid hormone on the level of TSH is impaired, and it take several months to become normal, in the primary hypothyroidism this effect is normal and you can take the TSH level to monitoring but after hypothyroidism due to treatment of thyrotoxicosis( graves) the best parameter for monitoring the treatment is T4 level
the correct answer is 2. T4 LEVEL
The correct answer is TSH !
Becasse of thyrotoxicosis (it means excessive thyroid hormones, the level effect of thyroid hormone on the level of TSh is impaired and it only takes SIX WEEKS !!!! not months !!!
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