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  #1  
Old 07-28-2011
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Question What thyroid disease affects this pregnant woman

A 28 y/o G1P0 woman at 12 weeks gestation presents for routine follow up with her obgyn. She complains of mild nausea and occasional vomiting, but otherwise is doing well and reports no other symptoms or complications. Her physical exam is unremarkable and fetal ultrasound is normal for gestational age. Lab test show:

Free triiodothyronine: 180
Free thyroxine: 2.2
Total thyroxine: 12
TSH: 0.1 (0.4-4)

Results of thyroid stimulating hormone receptor antibody are negative. Which of the following best explains these findings?

A. Acute infectious thyroiditis
B. Grave's disease
C. Hashimotos's disease
D. High serum estrogen concentration
E. High serum B-human chorionic gonadotropin level

Last edited by aksyonez; 07-28-2011 at 03:47 AM. Reason: wrong title
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Old 07-28-2011
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Quote:
Originally Posted by aksyonez View Post
A 28 y/o G1P0 woman at 12 weeks gestation presents for routine follow up with her obgyn. She complains of mild nausea and occasional vomiting, but otherwise is doing well and reports no other symptoms or complications. Her physical exam is unremarkable and fetal ultrasound is normal for gestational age. Lab test show:

Free triiodothyronine: 180
Free thyroxine: 2.2
Total thyroxine: 12
TSH: 0.1 (0.4-4)

Results of thyroid stimulating hormone receptor antibody are negative. Which of the following best explains these findings?

A. Acute infectious thyroiditis
B. Grave's disease
C. Hashimotos's disease
D. High serum estrogen concentration
E. High serum B-human chorionic gonadotropin level
Are they in SI reference range?
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Old 07-28-2011
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it's not graves since stimulating Ab is negative.

it's not hashimoto cuz tsh is low (must be elevated).

it's not high estrogen cuz the pt. must be euthyroid (only total t4 will be increased, free t4 should be normal and tsh should be normal too.

it's not acute infectious cuz there is no history of viral infection or tenderness over thyroid.

that leaves my answer as E. (i remember something about b-hcg having some thyrotropic action, one subunit being common for both)

(P.S: i had to look up the SI values to arrive at the answer.)
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Old 07-28-2011
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i think answer is e...alpha unit of HCG are similar to thyrotropin, Lutenizing harmone, FSH....so TSH is low( as u gave 0.4 to 4 but it is o.1) due to increase HCG--> increase thyrotropin and decreased TSH.....am i correct?
What is the answer.....?
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Old 07-28-2011
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i will go with E
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Old 07-28-2011
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Default Elimination method...

I dont know if hcG has any effect, but all the other options doest seem to fit.

So, E
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Old 07-28-2011
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It's E, HCG is similar to TSH.
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Old 11-16-2011
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Yep, the correct answer should be E (using elimination method)...and here is the explanation:

During normal pregnancy, the direct stimulatory effect of hCG on thyrocytes induces a small and transient increase in free T4 levels near the end of the first trimester (peak circulating hCG), resulting in a partial TSH suppres*sion. When tested in bioassays, normal hCG is only about 1/100 as potent as TSH. This weak thyrotropic activity explains why, in normal conditions, the effects of hCG remain largely unnoticed.

What thyroid disease affects this pregnant woman-thyroid-pregnancy.jpg

In
Williams Textbook of Endocrinology, 12th ed.; (2011) CHAPTER 11
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