Endocrine Disorders Flashcards
L.S.is a 32-year-old, 50-kg woman recently given a diagnosis of secondary hypothyroid disease caused by idiopathic panhypopituitarism. She began treatment with levothyroxine 75 mcg orally once daily 2 weeks ago. The results of today’s thyroid function tests are as follows: total thyroxine (TT4) 4 mcg/dL (normal level 5 to 12), total triiodothyronine (TT3) 75 ng/dL (normal level 80–180), and thyroid-stimulating hormone (TSH) less than 0.1 mIU/mL (normal level 0.4–4.0).
Given these laboratory tests, which one of the following is the best thyroxine (T4) dose adjustment for L.S.?
A. Increased because triiodothyronine (T3) and T4 levels are low.
B. Decreased because TSH levels are low.
C. Unchanged because free T4 levels are not available.
D. Unchanged because she has not yet reached steady state on this dose.
The half-life of T4 in a euthyroid patient is about 1 week. This patient has been receiving therapy for 2 weeks, or about 2 half-lives. Steady state is reached in about 5 half-lives (5 weeks) (Answer D is correct). Levels of FT4 and TT3 should be repeated after 3 to 4 additional weeks of therapy, with goal levels in the upper limits of the normal ranges (Answers A and C are incorrect).
Because this patient has secondary HoTR, her TSH level will always be low (Answer B is incorrect); this does not represent overreplacement, as would be the case in primary HoTR.
Correct Answer D
- T.R. is a 68-year-old white woman with a history of
angina and hypertension (HTN) who recently received
a diagnosis of hyperthyroidism (HTR) and is markedly
symptomatic. She is to undergo radioactive iodine
therapy in 6 weeks. Which one of the following is the
best initial pharmacologic therapy for T.R. to relieve
her symptoms?
A. Propranolol 40 mg orally 4 times/day.
B. Methimazole 10 mg orally 2 times/day.
C. Potassium iodide and iodine solution 5 drops
orally 3 times/day.
D. Propylthiouracil 100 mg orally 3 times/day.
- This patient with hyperthyroidism is markedly symptomatic and has a history of angina. Prompt symptom reduction that will not interfere with the planned RAI therapy is indicated.
β-Blockers take effect within hours of administration and do not interfere with the efficacy of RAI (Answer A is correct).
Lugol solution has a much quicker onset of action than thioamides, but it still takes days to work. In addition, iodides taken before RAI uptake therapy will prevent uptake of RAI by the thyroid gland, rendering its use ineffective (Answer C is incorrect). Thioamides inhibit organification and coupling, but they do nothing to stored thyroid hormone levels; thus, several weeks are required before a reduction is seen
in hyperthyroid symptoms (Answers B and D are incorrect).
Correct Answer: A
- L.R. is a 25-year-old obese woman given a diagnosis of polycystic ovary syndrome (PCOS) 4 years ago after presenting to her primary care physician with oily skin, acne, and excessive facial hair. She has managed these symptoms through weight loss and use of spironolactone 100 mg twice daily. She presents today with acanthosis nigricans and elevated blood pressure (BP) (142/90 mm Hg). Which one of the following choices is best for L.R.?
A. Clomiphene.
B. Metformin.
C. Finasteride.
D. Flutamide.
- The patient is showing signs of insulin resistance (acanthosis nigricans) and HTN. In addition to reducing blood glucose, metformin might allow her to lose weight, which will also decrease her insulin resistance and BP (Answer B is correct). Clomiphene is used to induce ovulation, thereby treating infertility (Answer A is incorrect). Finasteride is a 5-α-reductase inhibitor used to treat acne and hirsutism by inhibiting the conversion of T to its active metabolite in the hair follicle (Answer C is incorrect). Like spironolactone, flutamide is an antiandrogen, but potential hepatotoxicity limits its use (Answer D is incorrect).
Correct Answer: B
- Compared with women, how do men with prolactinomas most commonly present?
A. With fewer symptoms.
B. With a microprolactinoma.
C. At an earlier age.
D. With higher prolactin levels.
- Men usually present at an older age, with more symptoms, with macroprolactinomas versus microprolactinomas (Answers A, B, and C are incorrect) and with higher prolactin levels than in women (Answer D is correct), because women are typically identified much earlier during the disease because of changes in menstruation.
Correct Answer: D
- D.V. is a 64-year-old man who has been receiving
octreotide therapy for almost a year for the treatment
of acromegaly after transsphenoidal pituitary surgery.
Because of continued elevated growth hormone (GH)
and insulin-like growth factor (IGF)-1 levels, pegvisomant was initiated 2 months ago. His current IGF-1 level is normal, but his GH level is twice as high as it was before starting pegvisomant. Which one of the following explanations is most likely?
A. Recurrence of the GH-producing pituitary tumor.
B. Too low a dose of pegvisomant.
C. Too low a dose of octreotide.
D. Normal response to pegvisomant treatment.
- Unlike somatostatin analogs that directly inhibit GH secretion, pegvisomant is a GH receptor antagonist. It blocks the binding of endogenous GH to its receptor sites, leading to decreased IGF-1 levels. However, because it is a modified GH molecule, it is detected by commercial GH assays, thereby interfering with GH level measurements and causing falsely elevated GH levels (Answer D is correct). Because IGF-1 levels have decreased, Answers A, B and C are incorrect.
Correct Answer: D
- In the above case, if D.V. subsequently develops weakness, fatigue, anorexia, dizziness, and hypotension (BP 88/50 mm Hg), with which one of the following would be best to treat empirically?
A. Octreotide LAR.
B. Levothyroxine.
C. Hydrocortisone.
D. Testosterone.
- Patients after pituitary surgery are at an increased risk of pituitary failure, with subsequent decreases in GH, LH/ FSH, TSH, ACTH, and antidiuretic hormone secretion caused by pituitary injury because of the surgery. If this patient exhibits symptoms of adrenal deficiency, he should empirically be initiated on adrenal hormone replacement therapy even
before a definitive diagnosis is made (Answer C is correct). Levothyroxine (Answer B is incorrect) is used to treat HoTR and testosterone (Answer D is incorrect) is used to treat hypogonadism, not adrenal insufficiency. Octreotide LAR is a long-acting somatostatin preparation (Answer A is incorrect) used to treat acromegaly, not adrenal insufficiency.
Correct Answer: C
- A 20-year-old woman presents to your clinic for an
initial visit. She has always been heavy, but she has
gained almost 18.2 kg since starting college 3 years
ago. She has a diet rich in convenience and snack
foods. She has several alcoholic beverages on most
weekends and does not smoke. She played soccer competitively before college, but she now finds little time for regular physical activity. Her father is overweight and has type 2 diabetes mellitus (DM) and HTN. The patient denies polyuria, polydipsia, blurred vision, changes in her skin or hair, changes in her menses, or cold intolerance. On physical examination, she is 66 inches tall and weighs 99.5 kg; her body mass index (BMI) is 35 kg/m2. Her BP is 148/92 mm Hg. Which one of the following would be the most appropriate management of obesity in this patient?
A. Phentermine 8 mg three times per day with meals,
plus a low-carbohydrate diet.
B. Phentermine topiramate 15/92 mg every morning
plus a calorie-restricted diet with a calorie deficit
of 500 kcal/day, less than 10% calories from saturated fat, and limited refined sugars.
C. A diet with a calorie deficit of 500 kcal/day, less
than 30% calories from fat, and limited refined
sugars, combined with a progressive exercise
program.
D. An exercise prescription for 60 minutes of soccer five times per week with a plan to increase to
every day.
- In general, lifestyle changes need to be attempted before initiating drug therapy for weight loss (Answers A and B are incorrect) In addition, the poorly controlled BP makes these poor choices. A multifaceted approach is the most effective means to treat obesity; therefore, Answer C is correct. Answer D is somewhat reasonable, but relying totally on exercise for weight reduction in a patient who “finds little time for regular physical activity” is unrealistic (Answer D is incorrect).
Correct Answer: C
- N.M. is a 67-year-old man with significant heart disease who recently received a diagnosis of Cushing
syndrome caused by an adrenal tumor. He also
receives twice-daily high-dose lansoprazole for severe
gastroesophageal reflux disease. Given that he is not
a surgical candidate because of his heart disease,
which one of the following treatments would be best
to initiate?
A. Ketoconazole.
B. Metyrapone.
C. Eplerenone.
D. Spironolactone.
- Eplerenone and spironolactone are aldosterone antagonists used to treat hyperaldosteronism, not Cushing syndrome (Answers C and D are incorrect). Ketoconazole and metyrapone are used to treat Cushing syndrome, but ketoconazole requires an acidic stomach pH for absorption. Because this patient is receiving high-dose proton pump inhibitor therapy (Answer A is incorrect), metyrapone would be the
better choice (Answer B is correct).
Correct Answer: B
