T3,T4 and Tsh HELP??

  1. I am a nursing student in my last semester. I have an exam in G.I. this coming week and there might be a essay question about T3 T4 and TSH and how they interact. Can someone please explain this to me. I am not understanding it by reading the book. Thanks
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  2. 10 Comments

  3. by   bargainhound
    High TSH means the hormone is trying to stimulate thyroid production
    and the T3 and T4 levels are usualy low in this case.

    It means the dose of thyroid med needs to be adjusted higher.
    Or........the patient needs to start on thyroid supplement.

    Folks on thyroid supplements have levels checked about every 3 months
    or maybe longer intervals to make sure their current dose is
    appropriate.
  4. by   leslie :-D
    the TSH stimulates your thryoid gland to make and release thyroid hormones.
    if thyroid hormones (T3, T4) are decreased, TSH will increase to compensate for the low thryoid hormone levels.

    if your doctor orders a TSH and it is normal, there is no further indication for testing.
    but when your TSH is abnormal, then T3 and T4 levels needs to be tested.

    elevated T3, T4 levels with a decreased TSH (since the TSH doesn't have to stimulate release of thyroid hormones) is suggestive of hyperthyroid.

    decreased T3, T4 levels w/an increased TSH (low T3, T4 levels require TSH to pump out more thyroid hormone) is suggestive of hypothyroidism.

    do you see the relationship?
    i did try and simplify it, lol!

    leslie

    eta: why is this a part of your gi concept?
    shouldn't this be under endocrine?
  5. by   IU95
    The system operates on a negative feedback loop. Higher T3 & T4 means TSH decreases. Low T3 & T4 means TSH increases.

    You might see FTI (free thyroxine index) too. This is a calculated value obtained by multiplying the T3 uptake times the T4. This result shows how much thyroid hormone is free in the blood.

  6. by   Julie029
    Yes it is endocrine which is actually covered in our G.I class. Your explanation was very helpful. Thanks
  7. by   Julie029
    Thanks for the explanations. I do understand it now.
  8. by   777RNThatsMe
    What may occur on tests re thyroid is thyroid storm...which is when the T3/T4 either one...are too elevated... and the patient will go into possible cardiac arrest but usually starts w/like...fast heartbeat, sweating etc.... they have to give an anti-thyroid medicatioin (I THINK Im trying to remember what..) to block it.... they can block uptake...of course I believe they also give heart drugs if need be but again...search for thyroid storm.

    The other thing you need to know is that on the thyroid sit the parathyroid glands...which control some of the calcium in the bloodstream... they release PTH to INcrease the uptake of calcium into the bloodstream so like....when they have a partial or total thyroidectomy....the parathyroid can be bumped..causing a dump of PTH....and a sudden increase in calcium in the blood...so a person has to be careful to watch calcium levels right after this surgery....

    The other thing you may be tested on is the fact that the thyroid is a very vascular organ..so high risk for bleed.

    Anyway.... what the others wrote about the t3/t4 is true..it is a negative feedback endocrine loop. What you may also need to know is...if the levels get low..it is the pituitary gland that senses this...and sends the signal to release or lower the TSH...to get the thyroid to either cut back or pump out more t3/t4. The thyroid gland produces t3 and t4..but not tsh. Tsh comes from the pituitary....

    Sometimes....they can be "off" due to a pituitary tumor...also.
    Also, stress can throw them off...
    Also... hashimotos thyroiditis.... which is The most common type of hypothyroidism (which is the thyroid isnt putting out enough of the t3/t4... so therefore the tsh will elevate as the pituitary says "yo! Pump it out! We are low here!" TSH is like the kick in the pants to tell the thyroid to put out t3/t4 so the body can use it...so to speak.

    The other thing is graves disease..which is the formal term for hyperthyroid....oftentimes this is from thyroid nodules... but it's where it puts out too much t3/t4..therefore the pituitary lowers the tsh..to tell the thyroid to slow down....
    But sometimes..the thyroid doesn't listen...and then you get elevated t3/t4 which can cause thyroid storm....that emergency I told you about....

    Also when the medication (usually a synthetic form of t4 but sometimes with combination synthetic t3)...is too high...they can hit storm.

    When they are too low....then usually the body slows down too much..and people may get really slow in speech, etc....well then they need the medication. If they had thyroid cancer...or whatever..a goiter etc and had their thyroid removed or partially removed..they will also be on thyroid replacement (which is the t4...and/or the t3 synthetic hormone)..

    This is NOT an easy thing to fix...or keep level.... folks can/will go up and down... the endocrine system is a fast/adjusting system...but when we give synthetic hormones...we dont adjust fast like our system does....so as people change...sometimes the meds don't change too and people do need adjustements at times...

    AT the same time.... people who have to take thyroid medication USUALLY have to take it for a lifetime.

    Hope that helps. Double check me by searching thyroid problems... It's all over the net b/c it's quite common.

    Oh - also people who eat soy can sometimes have issues w/thyroid...so those w/thyroid issues are usually told not to have soy....at least from what I understand.

    OH and then you have peds...the congenital hypothyroidism..(cretinism..I believe it's called) can be treated w/medication (again t4/t3)..... and must be..or else you get mental retardation etc...but with the med...prognosis is very good.
    Last edit by 777RNThatsMe on Sep 5, '06
  9. by   TheCommuter
    Quote from 777RNThatsMe
    What may occur on tests re thyroid is thyroid storm...which is when the T3/T4 either one...are too elevated... and the patient will go into possible cardiac arrest but usually starts w/like...fast heartbeat, sweating etc.... they have to give an anti-thyroid medicatioin (I THINK Im trying to remember what..) to block it.... they can block uptake...of course I believe they also give heart drugs if need be but again...search for thyroid storm.
    The name of this anti-thyroid medication is methimazole (Tapazole). I took it on and off for 7 years. There's another less-commonly prescribed anti-thyroid drug called PTU. The so-called heart drug commonly given to hyperthyroid patients and those suffering from thyroid storm is metoprolol (Lopressor) in high doses. Some doctors prefer other beta blockers, but Lopressor and Tapazole seem to be a common combination for hyperthyroid therapy.
  10. by   TheCommuter
    Quote from Julie029
    Yes it is endocrine which is actually covered in our G.I class. Your explanation was very helpful. Thanks
    Thyroid problems can also have a gastrointestinal connection, too. People suffering from hypothyroidism (sluggish thyroid) usually have slow metabolic rates and constipation. In other words, their gastrointestinal motility is entirely slow due to the disease process.

    People suffering from hyperthyroidism (overactive thyroid) tend to have fast metabolic rates and diarrhea. In other words, their gastrointestinal motility is rapid due to the disease process.
  11. by   charebec65
    Awesome thread! Endocrine was the bane of my existance for some reason.... Thanks guys......!
  12. by   EricJRN
    Thyroid problems can also have a nutritional link, so that may be another reason for the seemingly strange inclusion in the GI section.

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