Physiology of TRH and TSH

CME QUESTIONS - PHYSIOLOGY OF TRH AND TSH BACK
PREPARED BY STEPHANO MARIOTTI, MD

Reading for this module should include Chapter 4 in Thyroid Disease Manager, or alternative sources. These could include chapters in Endocrinology, Edition III, comparable chapters in Endocrinology Edition IV (when released), or appropriate chapters in “The Thyroid”.

Anticipated study and testing time for this module is 3 hours. After reading the material, print out his page, complete the test, fill in required personal information, and send the page with payment to

Center for Continuing Medical Education, 950 E 61^st St., University of Chicago, Chicago, IL 60637., with payment of $45. After satisfactory completion of the examination, a certificate will be returned by mail.

1. Thyroid-Stimulating Hormone (TSH) molecule is:
	A. A monomer
	B. A homodimer
	C. A heterodimer of alpha and beta subunits covalently bound
	D. A tetramer of alpha, beta, gamma and delta subunits
	E. A heterodimer of alpha and beta subunits non-covalently bound

3. The biosynthesis of mature, bioactive TSH implies:
	A. Excision of signal peptides from both alpha and beta subunits
	B. Co-translational glycosylation
	C. Lysosomal digestion
	D. Sulfatation
	E. Iodination

5. The biological activity of TSH is affected by:
	A. TSH glycosylation
	B. The amount of co-secreted alpha subunit
	C. The amount of co-secreted free beta subunit
	D. TRH
	E. Nycto-hemeral rythm

6. The increased TSH production in hypothyroidism is due to:
	A. Increased number of thyrotropic cells secreting normal TSH amount
	B. Increased TSH secretion by a normal number of thyrotropic cells
	C. Increased number of thyrotropic cells secreting increased amounts of TSH
	D. Very increased number of thyrotropic cells secreting lower than normal TSH amount
	E. A reduced number of thyrotropic cells secreting very high TSH amount

7. The inhibitory effect of thyroid hormone on pituitary TSH secretion is mainly due to:
	A. Serum T3
	B. Serum T4
	C. T3 generated at the pituitary level from serum T4
	D. Intrapituitary T4
	E. A + C

8. Thyrotropin-Releasing Hormone (TRH) :
	A. Is a peptide
	B. Is a glycoprotein
	C. Is synthesized as pre-pro-TRH mainly in the paraventricular nuclei of the hypothalamus
	D. Derives from pre-pro TRH by proteolytic cleavage in the serum
	E. Derives from pre-pro TRH by proteolytic cleavage during the axonal transport to the neurohypophysis

9. TRH activity is mediated by:
	A. A membrane G-protein-coupled receptor
	B. A nuclear receptor
	C. A second messenger mainly represented by cAMP
	D. A second messenger mainly represented by intracellular Ca++
	E. A second messenger mainly represented by intracellular K+

10. Modern immunometric techniques allow the detection in the serum of:
	A. Free TSH alpha-subunit
	B. Free TSH beta-subunit
	C. Intact TSH
	D. Carboxy-terminal fragments of TSH
	E. Amino-terminal fragments of TSH

11. The normal range for serum TSH in humans is approximately:
	A. 0.2 – 4.5 mU/L
	B. 0.2 – 4.5 mU/ml
	C. 1 – 5 mg/L
	D. 6 – 12 mg/dL
	E. 0.2 – 4.5 pg/ml

12. TSH secretion in human is:
	A. Pulsatile with a circadian rythm
	B. Pulsatile without a circadian rythm
	C. Non-pulsatile with a circadian rythm
	D. Maximal in the late morning
	E. Maximal between 23:00 and 02:00 hours in the night
13. The serum TSH concentration decreases in:
	A. Starvation
	B. Severe non-thyroidal illnesses
	C. Anorexia nervosa
	D. All of the above
	E. None of the above
14. The serum concentration of TSH increases:
	A. In primary hypothyroidism
	B. During the recovery phase of non-thyroidal illnesses
	C. After glucorticoid administration
	D. In acute psychosis
	E. In thyroid hormone resistance syndrome

15. Serum TSH is always undetectable by highly sensitive immunometric assays in:
	A. In untreated overt hyperthyroidism
	B. In congenital TSH deficiency
	C. In euthyroid Graves’ disease
	D. In severe non-thyroidal illnesses
	E. In central hypothyroidism

Answer Sheet
Enter "True" or "False" in the appropriate boxes.
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Was there a topic not covered you would have liked to have had presented? Please specify.

Do you believe the presentations contained pharmaceutical industry bias? Yes __ No __ Comments:

I certify that I spent three hours in preparation and examination for this module-

2. The alpha subunit of TSH is common to:
	A. LH
	B. FSH
	C. HCG
	D. A + B + C
	E. GH

4. The moleculr weigh of the entire TSH molecule is:
	A. 280,000 Da
	B. 28,000 Da
	C. 2,800 Da
	D. 50,000 Da
	E. 5,000 Da