NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE PartIll - Additional Testing
ID: 3515235 • Letter: N
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NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE PartIll - Additional Testing Dr. O'Dell continued. "Low TSH levels should result in low thyroxin levels, not the reverse. Something seems to be stimulating the thyroid in the absence of TSH. When I saw your results, I spoke to Dr. Rasam and he suggested a special ELISA test on the blood sample I collected from you. The ELISA result indicates that Carrie shows early signs of Graves disease." Both Carrie and Robert looked confused. Carrie, a subset of your immune system antibodies is mistakenly attacking your thyroid gland, causing an increase in hormone production. Common symptoms include insomnia, anxiety, fatigue, heat sensitivity, weight loss, and increased sweating. Your hair might get brittle, and your menstrual cycle might change. Carrie nodded. "I've had all those symptoms." "But this Graves disease can be cured, right?" asked Robert, holding Carrie's hand tightly. It's treatable, yes, but this autoimmunity is a lifelong problem that has to be carefully managed to avoid symptoms such as eye swelling or bulging often seen in Graves patients, as well as other complications." Questions 1. Consider the immunological involvement in this case, and the time frame over which it has occurred. a. Which antibody (Ig) class was produced first in this sequence of events? b. Which class is most likely involved in an ongoing autoimmunity situation? 2. Return to your thyroid-pituitary diagram. Explain the consequences to both thyroxin and TSH levels: a. if the auto-antibodies are against the thyroxin molecule. b. if the auto-antibodies are against the TSH molecule 3. Does either scenario in Question 2 above fit Carrie's hormone data? 4. Anti-receptor antibodies can block hormone entry or stimulate the receptor (like original hormone). Use your diagram to explain the consequences to both thyroxin and TSH levels if the auto-antibodies: a. block the thyroxin receptors on the pituitary b. stimulate the thyroxin receptors on the pituitary c. block the TSH receptors on the thyroid. d. stimulate the TSH receptors on the thyroid. 5. Does any scenario in Question 4 fit Carrie's hormone data? What must be the problem in Graves disease? 6. Identify the type of hypersensitivity (by name and number) that Carrie is experiencing.Explanation / Answer
1.a. Antibodies to TSH and thyroglobulin is produced first. They bind to the receptor of TSH and stimulate it.
b. Thyroid stimulating immunoglobulins which activate the cells slowly taking longer time than thyroid stimulating hormone, leads to an elevated production of thyroid hormone.
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