Question

Thyroid case study 3 Design Layout References Mailings Review View Table Design Layout 14 AA AA EE 93 21 Aalbot Aalbo ABC XX ALA EEEEEE No Spacing Heading! ABCD Aa Bb Heading The C Sun Dr. Siddiqui calls Angela and asks her to come back to the clinic to discuss her results. It appears that Angela has a hormone-suppressing tumor in either the hypothalamus or anterior pituitary. Dr. Siddiqui wants to do some tests to confirm a tumor and determine where the tumor is located. Dr. Siddiqui recommends that Angela go for an MRI, a CAT scan or a PET scan to see if a tumor is visible. She also recommends a TRH challenge test. QUESTIONS 1. Knowing what you do about the HPT axis, what hormonal information would you need to determine if the hormone-suppressing tumor is in the hypothalamus or anterior pituitary? Why is it near impossible to get this information (consider location for hormone release)? 2. Dr. Siddiqui injects Angela with a dose of TRH and draws a blood sample to measure TSH and thyroid hormone levels. What results would you expect if the tumor is in the hypothalamus? The anterior pituitary? Use the table below to organize your answers (state high or low) and then explain your rationale for your answer below. Hypothalamus tumor Anterior pituitary tumor TSH Thyroid Hormones words o English (United States) O Focus

Answer 1

2. Hypothalamus tumor: TSH - High ; Thyroid Hormones - High

Anterior pituitary tumor: TSH - Low ; Thyroid Hormones - Low

Hypothalamus TRH Antenor pituitary TSH Thyroid gland E T3,T4

As you can see in the Hypothalamus - Pituitary - Thyroid axis, when the tumor is in the hypothalamus, administered TRH will act on anterior pituitary to cause increased release of TSH, which in turn act on thyroid gland to cause increased release of thyroid hormones.

When tumor is in the anterior pituitary, administered TRH cannot produce any effect on anterior pituitary as its hormone release is suppressed by the tumor. Hence, there is low level of TRH and thyroid hormones in the blood.

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