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Old 11-15-2012
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ObGyn Thyroid Hormone Function Test in Pregnancy

A 28-year-old G1P0 woman at 12 weeks’ gestation presents for routine follow-up with her obstetrician. She complains of mild nausea and occasional vomiting, but otherwise is doing well and reports no other symptoms or complications. Her physical examination is unremarkable and fetal ultrasound is normal for gestational age. Laboratory tests show:
Free triiodothyronine 180 ng/dL
Free thyroxine 2.2 ng/dL
Total thyroxine 12 g/dL
Thyroid-stimulating hormone 0.1 U/mL
Results of a thyroid-stimulating hormone– receptor antibody test are negative. Which of the following explains these findings?

(A) Acute infectious thyroiditis
(B) Graves’ disease
(C) Hashimoto’s thyroiditis
(D) High serum estrogen concentration
(E) High serum -human chorionic gonadotropin concentration
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Old 11-15-2012
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D.....increased synthesis of transport proteins....normal free T4 n increased total T4
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Matched!!!
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The correct answer is E. The two most important factors that affect thyroid physiology in the pregnant patient are estrogen and β-human chorionic gonadotropin. Early in pregnancy, when β-human chorionic gonadotropin (β-hCG) levels peak at 1012 weeks, patients can have subclinical hyperthyroidism because β-hCG is a weak stimulator of the thyroid stimulating hormone (TSH)-receptor and this stimulation causes excess production of thyroid hormones and a subsequent decline in TSH due to negative feedback on the pituitary, as is seen in this patient. This transient subclinical hyperthyroidism occurs in 1020% of patients and usually does not require therapy.. In addition, patients with hydatidiform mole or choriocarcinoma can have severe hyperthyroidism.

Answer D is incorrect. Elevated serum estrogen levels also cause a major change in thyroid function. Estrogen increases production as well as decreases clearance of thyroid-binding globulin. This causes an increase in total thyroxine (T4), but the free triiodothyronine (T3) and T4 remain normal. The patient is clinically euthyroid and the TSH is normal. These abnormalities will typically be found in pregnant patients.
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Old 11-17-2012
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Quote:
Originally Posted by heartbeat View Post
The correct answer is E. The two most important factors that affect thyroid physiology in the pregnant patient are estrogen and β-human chorionic gonadotropin. Early in pregnancy, when β-human chorionic gonadotropin (β-hCG) levels peak at 10–12 weeks, patients can have subclinical hyperthyroidism because β-hCG is a weak stimulator of the thyroid stimulating hormone (TSH)-receptor and this stimulation causes excess production of thyroid hormones and a subsequent decline in TSH due to negative feedback on the pituitary, as is seen in this patient. This transient subclinical hyperthyroidism occurs in 10–20% of patients and usually does not require therapy.. In addition, patients with hydatidiform mole or choriocarcinoma can have severe hyperthyroidism.

Answer D is incorrect. Elevated serum estrogen levels also cause a major change in thyroid function. Estrogen increases production as well as decreases clearance of thyroid-binding globulin. This causes an increase in total thyroxine (T4), but the free triiodothyronine (T3) and T4 remain normal. The patient is clinically euthyroid and the TSH is normal. These abnormalities will typically be found in pregnant patients.
weird Q ...
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Old 11-19-2012
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Quote:
Originally Posted by aknz View Post
weird Q ...
Not that much the alpha subunit of the TSH is nearly identical to that of HCG and LH...I missed this question a couple of times
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Old 11-20-2012
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Quote:
Originally Posted by heartbeat View Post
A 28-year-old G1P0 woman at 12 weeks’ gestation presents for routine follow-up with her obstetrician. She complains of mild nausea and occasional vomiting, but otherwise is doing well and reports no other symptoms or complications. Her physical examination is unremarkable and fetal ultrasound is normal for gestational age. Laboratory tests show:
Free triiodothyronine 180 ng/dL
Free thyroxine 2.2 ng/dL
Total thyroxine 12 g/dL
Thyroid-stimulating hormone 0.1 U/mL
Results of a thyroid-stimulating hormone– receptor antibody test are negative. Which of the following explains these findings?

(A) Acute infectious thyroiditis
(B) Graves’ disease
(C) Hashimoto’s thyroiditis
(D) High serum estrogen concentration
(E) High serum -human chorionic gonadotropin concentration
pregnancy.------> high hcg.
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