Anatomy

Courtney Takahashi, Dean Fraser, Carrie Marshall, Hazel Abinsay, Mark Valdez, Shauna Conry Endocrine Mystery Cases 27 April 2006 Please see my feedback in red. 1. Disturbance 4, bitemporal hemianopsia Correct. 2. Increased pigmentation, decreased levels of adrenal glucocorticoids and mineralocorticoids, what condition is he suffering from? Answer: A, primary adrenocortical insufficiency (Addison’s disease) • In Addison’s disease, there are increased levels of ACTH. ACTH contains a MSH-α fragment, which increases pigmentation • The treatment for Addison’s disease is the administration of glucocorticoids and mineralocorticoids since the destroyed adrenal cortex can no longer produce them Correct. Nice explanation (although, I’m assuming you know why ACTH is increased in this disease). Note that leading theories for increased pigmentation is ACTH itself acting on the melanocyte receptor and/or POMC derivatives of MSH. 3. Patient X suffering from galactorrhea, secondary to excessive prolactin levels Answer: C is the thyroid As the flowchart shows, the pituitary gland and subsequent prolactin release is stimulated by TRH. Therefore, if a patient were suffering from a condition such as hypothyroidism, we would expect levels of T3 and T4 to be low in the body. Since the thyroid and hypothalamus as controlled by negative feedback loops from T3 and T4, the low levels would stimulate an increase in TRH from the hypothalamus and an increase in prolactin. The high levels of prolactin can cause galactorrhea in a patient. Chart and information from:

http://www.aafp.org/afp/20010501/1763.html

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Try again. You do have the correct answer choice … however, I would like a clearer explanation on the link between thyroid and increased prolactin secretion. 4. Haane has to use the bathroom constantly. Blood and urine samples were taken and gave the following results: • Plasma osmolarity: increased • Urine osmolarity: decreased • Urine osmolarity after water deprivation: no change • Plasma ADH: high Haane’s laboratory results are consistent with nephrogenic diabetes insipidus. Her kidneys are unresponsive to ADH. • Her plasma osmolarity is increased because she is excreting excess water in her urine which concentrates her plasma • Her urine osmolarity is decreased even after water deprivation (which normally would concentrate the urine) because her kidneys are unresponsive to ADH and therefore cannot concentrate urine. • Her plasma ADH is high because her high plasma osmolarity stimulates the posterior pituitary to secrete ADH despite the unresponsive nature of her kidneys. Correct. Excellent explanation. 5. Millie’s neural stalk was severed during surgery. She soon notices a milky discharge from her nipples. Hypothalamus

Dopamine (-) Anterior Pituitary

Prolactin

Breast

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The production of milk is a positive feedback loop is inhibited by dopamine. If Millie’s neural stalk was injured, then she no longer has the dopamine suppression of milk production; hence the discharge from her nipples. Correct. Very good. 6. If a person was given glucocorticoid drugs, which zones of the adrenal gland would atrophy? Zona fasciculata and zona reticularis. The thicker middle zona fasciculata and the compact innermost zona reticularis produce cortisol and androgens. They are regulated by ACTH. (Endocrine pathophysiology, p. 85) Correct. 7. CRH decreased, ACTH increased, cortisol increased, adrenal androgen increased by patient still experiences impotency and decreased libido. Diagnosis? Cushing’s disease / Pituitary adenoma. • CRH is decreased because high levels of cortisol feedback on the hypothalamus and prevent CRH secretion • ACTH levels remain high because cortisol levels are not high enough to inhibit the secretion by the tumor • High ACTH  high cortisol levels Endocrine Pathophysiology, p. 85-87 Correct. (Would you happen to know another cause of Cushing’s syndrome that could explain these clues?) 8. CRH decreased, ACTH decreased, Cortisol increased, no clinical manifestations of androgen or mineralocorticoid excess Adrenal adenoma • CRH and ACTH are decreased show that the high levels of cortisol are exhibiting negative feed back on the hypothalamus and pituitary. • The high level of cortisol implies that there is an inherent problem with the adrenal glands, such as a tumor that is independently releasing high levels of cortisol. Correct. (Again, would you happen to know another cause of Cushing’s syndrome that could explain these clues?) 9. Timmy the turtle moves slowly because of his hypothyroidism, how will his condition affect his calcitonin levels? His condition will probably not affect his calcitonin levels. Even though calcitonin is regulated by the thyroid gland, its release is governed by the level of extracellular calcium levels. Correct.

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10. E Correct. 11. C Correct. 12. A Correct. 13. D Correct. 14. E Correct.

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