Thyroid Hormones + Negative Feedback Loop

[Eri3]

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Can anyone offer an explanation for this Q?

A person w/ hyperthyroidism is tested for levels of T3 T4 and TSH? What would the expected levels be?

a) T3 high, T4 Low, TSH high
b) T3 high, T4 High, TSH high
c)T3 high, T4 high, TSH low
d) T3 Low, T4 Low, TSH low
e) T3 Low, T4 Low, TSH high

 

[yandillo]

Can anyone offer an explanation for this Q?

A person w/ hyperthyroidism is tested for levels of T3 T4 and TSH? What would the expected levels be?

a) T3 high, T4 Low, TSH high
b) T3 high, T4 High, TSH high
c)T3 high, T4 high, TSH low
d) T3 Low, T4 Low, TSH low
e) T3 Low, T4 Low, TSH high

Levels of the thyroid hormones themselves (T4 and T3) must be high for this diagnosis to be made.
Now, TSH is secreted from the pituitary gland with the purpose of stimulating the thyroid to produce thyroid hormone. The pituitary constantly monitors our thyroid hormone levels, and if it senses the slightest excess of thyroid hormone in blood, it stops producing TSH. Consequently, a low blood TSH strongly suggests that the thyroid is overproducing hormone on its own. So the answer should be c). Review feedback mechanisms because they can ask how will be the levels of TRH as well.

 

[Eri3]

Levels of the thyroid hormones themselves (T4 and T3) must be high for this diagnosis to be made.
Now, TSH is secreted from the pituitary gland with the purpose of stimulating the thyroid to produce thyroid hormone. The pituitary constantly monitors our thyroid hormone levels, and if it senses the slightest excess of thyroid hormone in blood, it stops producing TSH. Consequently, a low blood TSH strongly suggests that the thyroid is overproducing hormone on its own. So the answer should be c). Review feedback mechanisms because they can ask how will be the levels of TRH as well.

Thanks, I understood what would happen to T3 and T4 but I didn't think about the Thyroid Stimulating Hormone - that gives it away, it should be low b/c there is no need to stimulate the thyroid if T3 and T4 are being overproduced. TRH should be low since it stimulates the anterior pituitary to release TSH but there is no need for TSH since the thyroid is hyper-reactive???

 

[Xo1991]

dude....this is way too in-depth for the DAT.

What you need to know:
Thyroid hormones are iodine-derived.
Thyroid produces calcitonin, which does the opposite of parathyroid hormone. Calcitonin increases osteoblast activity by resorbing bone and decreasing blood calcium.

 

[wahaha]

TSH will be low and T3/T4 may be high is the simple answer if it is a tertiary hyperthyroidsim like grave's disease.

 

[yandillo]

Thanks, I understood what would happen to T3 and T4 but I didn't think about the Thyroid Stimulating Hormone - that gives it away, it should be low b/c there is no need to stimulate the thyroid if T3 and T4 are being overproduced. TRH should be low since it stimulates the anterior pituitary to release TSH but there is no need for TSH since the thyroid is hyper-reactive???

Dude u just said whatever I said with different words...u got it!! ..."if it senses the slightest excess of thyroid hormone in blood, it stops producing TSH" = "it should be low b/c there is no need to stimulate the thyroid if T3 and T4 are being overproduced"....

 

[Eri3]

Dude u just said whatever I said with different words...u got it!! ..."if it senses the slightest excess of thyroid hormone in blood, it stops producing TSH" = "it should be low b/c there is no need to stimulate the thyroid if T3 and T4 are being overproduced"....

haha yea cuz it clicked when i read your comment.

dude....this is way too in-depth for the DAT.


thats not true, ive already taken the DAT once. on hormones they love to test if your really understand something instead of just memorization.