Dr. Siddiqui, an endocrinologist, saw two new patients today, Tyra and Chris. He
ID: 3520660 • Letter: D
Question
Dr. Siddiqui, an endocrinologist, saw two new patients today, Tyra and Chris. He examined them and ordered some blood tests to determine what disorder they may have. The test results for Tyra and Chris are summarized in the above table.
For both Tyra and Chris, answer the following questions.
A. Which values are outside of normal range? Are they high or low?
B. Briefly describe the normal pathway that controls the hormones that are causing Tyra’s and Chris' disorders. Make sure to describe the appropriate negative feedback.
C. Are the test values consistent with hyposecretion or hypersecretion? Would this be an example of primary or secondary hypo- or hyper-secretion? Support your answer.
D. Do you expect Tyra or Chris to develop a goiter? Support your answer.
E. How would you treat Tyra to decrease her symptoms? (There is no need to answer this question for Chris).
Tyra's values Serum thyroxine (Ty (Hg/dL)1.8 Thyrotropin (TSH) (ulU/mL)0.3 TSI (immunoglobulins) Serum triiodothyronine (T3)57 ng/dL) Cortisol (ug/dL) ACTH (pg/mL) Chris' values 10.6 2.8 Normal 125 Normal values 4.6-12 0.5-6 Normal 80-180 Normal 12.3 34.2 56.9 2.5 5-23 20-50Explanation / Answer
Solutions
A.
Tyra’s T3, T4, and TSH are outside of normal range. It is lower than the normal values
For Chris, the ACTH and Cortisol levels are outside of normal range. The cortisol levels are above the normal range, and the ACTH levels are below the normal range.
B.
The thyroid stimulating hormone (TSH) is a hormone that is produced pituitary gland. It is a primary hormone. It is responsible for regulation of metabolism and release of secondary hormones from the thyroid gland, namely T3 and T4 (triiodothyronine (T3), thyroxine (T4)), and also calcitonin. When T3 and T4 levels are low, the hypothalamus responds by producing thyrotropin releasing factor (TRH). This in turn stimulates the production of TSH, which then goes on to stimulate the thyroid to produce more amounts of T3, and T4.
In the case of Chris, there is malfunctioning of the cortisol and ACTh negative feedback loop mechanism. The Adrenal cortex release the hormone cortisol under stress conditions. This hormone inhibits CRH (corticotropin releasing hormone) and ACTH (adrenocorticotropic hormone). When ACTH levels drop down, the adrenal gland stops producing cortisol, which increases the blood levels of ACTH.
C.
Tyra’s test results are a sign of Hyposecretion of TSH, T3, and T4. It is a type of secondary hypo-secretion, since the levels are controlled by TRH at the primary level.
Chris’s results are a sign of Hypersecretion of Cortisol. It is a type of primary hyposecretion.
D.
Since Tyra is suffering from hypothyroidism, she is at risk of developing Goitre. Since Chris’ thyroid glands seem to functioning normally, he is not at risk of developing Goitre.
E.
Hypothyroidism can be addressed with synthetic T4 hormone therapy called levothyroxine or synthroid. Sometimes, a mix of T4 and T3 made from animal thyroid glands can also be used.
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