Thyroid function testing — MCQs

An 18-year-old girl comes to the clinic because she is concerned about her weight. She states that she is on her school’s cheerleading team and is upset because she feels she is the “fattest” girl on the team despite her healthy diet. She says that in the last 2 weeks since practice began, she has lost 2 lbs. The patient has bipolar disorder I. Her medications include lithium and a combined oral contraceptive that was recently started by her gynecologist, because “everyone is on it." Her mother has hypothyroidism and is treated with levothyroxine. The patient’s BMI is 23.2 kg/m2. Thyroid function labs are drawn and shown below: Thyroid-stimulating hormone (TSH): 4.0 mIU/L Serum thyroxine (T4): 18 ug/dL Free thyroxine (Free T4): 1.4 ng/dl (normal range: 0.7-1.9 ng/dL) Serum triiodothyronine (T3): 210 ng/dL Free triiodothyronine (T3): 6.0 pg/mL (normal range: 3.0-7.0 pg/mL) Which of the following is the most likely cause of the patient’s abnormal lab values?

A 35-year-old woman presents to the clinic for a several-month history of heat intolerance. She lives in a small apartment with her husband and reports that she always feels hot and sweaty, even when their air conditioning is on high. On further questioning, she's also had a 4.5 kg (10 lb) unintentional weight loss. The vital signs include: heart rate 102/min and blood pressure 150/80 mm Hg. The physical exam is notable for warm and slightly moist skin. She also exhibits a fine tremor in her hands when her arms are outstretched. Which of the following laboratory values is most likely low in this patient?

A 30-year-old woman presents to her primary care physician for evaluation of irregular and heavy periods. She also complains of recent fatigue, joint pain, and constipation. Physical exam is notable for thinning eyebrows and recent weight gain. Her temperature is 98.0°F (36.7°C), blood pressure is 140/90 mmHg, 51/min, and respirations are 19/min. Laboratory studies reveal the following: Serum: Na+: 141 mEq/L K+: 4.3 mEq/L Cl-: 102 mEq/L BUN: 15 mg/dL Glucose: 115 mg/dL Creatinine: 1.0 mg/dL Thyroid-stimulating hormone: 11.2 µU/mL Total T4: 2 ug/dL Thyroglobulin antibodies: Positive Anti-thyroid peroxidase antibodies: Positive Which of the following is this patient at increased risk of in the future?

A 48-year-old woman is brought to the emergency department by her family at her psychiatrist's recommendation. According to her family, she has been more restless than her baseline over the past week. The patient herself complains that she feels her mind is racing. Her past medical history is significant for bipolar disorder on lithium and type 1 diabetes mellitus. The family and the patient both assert that the patient has been taking her medications. She denies any recent illness or sick contacts. The patient's temperature is 100°F (37.8°C), blood pressure is 100/60 mmHg, pulse is 130/min, and respirations are 20/min. She appears diaphoretic, and her cardiac exam is notable for an irregularly irregular rhythm with a 2/6 early systolic murmur. Blood counts and metabolic panel are within normal limits. The patient's lithium level is within therapeutic range. Which of the following laboratory tests would be the most useful to include in the evaluation of this patient?

A 39-year-old female presents to the clinic with the complaints of dry skin for a few months. She adds that she also has constipation for which she started eating vegetables and fruits but with no improvement. She lives with her husband and children who often complain when she turns the air conditioning to high as she cannot tolerate low temperatures. She has gained 5 kgs (11.2 lb) since her last visit 2 months back although her diet has not changed much. Her past medical history is relevant for cardiac arrhythmias and diabetes. She is on several medications currently. Her temperature is 98.6° F (37° C), respirations are 15/min, pulse is 57/min and blood pressure is 132/98 mm Hg. A physical examination is within normal limits. Thyroid function test results are given below: Serum TSH: 13.0 μU/mL Thyroxine (T4): 3.0 μg/dL Triiodothyronine (T3): 100 ng/dL Which of the following medications is most likely to be responsible for her symptoms?

A 52-year-old male presents to clinic with complaints of anxiety and fatigue for 4 months. He has also been experiencing palpitations, muscle weakness, increased sweating, and an increase in the frequency of defecation. Past medical history is insignificant. He neither consumes alcohol nor smokes cigarettes. His pulse is 104/min and irregular, blood pressure is 140/80 mm Hg. On examination, you notice that he has bilateral exophthalmos. There are fine tremors in both hands. Which of the following results would you expect to see on a thyroid panel?

A 37-year-old woman comes to the physician because of a 2-week history of palpitations and loose stools. She has had a 2.3-kg (5-lb) weight loss over the past month. She has had no change in appetite. She has no history of serious illness. She works in accounting and has been under more stress than usual lately. She takes no medications. She appears pale. Her temperature is 37.8°C (100.1°F), pulse is 110/min, respirations are 20/min, and blood pressure is 126/78 mm Hg. Cardiopulmonary examination shows no abnormalities. The abdomen is soft and nontender. There is a bilateral hand tremor with outstretched arms and a palpable thyroid nodule in the left lobe. Serum laboratory studies show a thyroid stimulating hormone level of 0.03 μU/mL and a thyroxine level of 28 μg/dL. A radioactive iodine uptake scan shows enhancement in a 3-cm encapsulated nodule in the lower left lobe with decreased uptake in the remaining gland. Which of the following is the most likely diagnosis?

A 23-year-old male presents with complaints of polydipsia and frequent, large-volume urination. Laboratory testing does not demonstrate any evidence of diabetes; however, a reduced urine osmolality of 120 mOsm/L is measured. Which of the following findings on a desmopressin test would be most consistent with a diagnosis of central diabetes insipidus?

A 29-year-old woman comes to her primary care physician hoping she is pregnant. She reports that she had been taking oral contraceptive pills, but she stopped when she began trying to get pregnant about 7 months ago. Since then she has not had her period. She took a few home pregnancy tests that were negative, but she feels they could be wrong. She says she has gained 4 lbs in the past month, and her breasts feel full. Today, she expressed milk from her nipples. She complains of fatigue, which she attributes to stress at work, and headaches, to which she says “my sister told me she had headaches when she was pregnant.” She denies spotting or vaginal discharge. Her last menstrual period was at age 22, prior to starting oral contraceptive pills. Her medical and surgical history are non-significant. She has no history of sexually transmitted infections. She reports she and her husband are having intercourse 3-4 times a week. Her family history is significant for breast cancer in her mother and an aunt who died of ovarian cancer at 55. On physical examination, no breast masses are appreciated, but compression of the nipples produces whitish discharge bilaterally. A bimanual pelvic examination is normal. A urine pregnancy test is negative. Which of the following is the best initial step in management for this patient?

A 40-year-old woman with a past medical history significant for pernicious anemia and vitiligo presents to the physician with the chief complaints of heat intolerance and frequent palpitations. The patient does not take birth control and her urine pregnancy test is negative today. Physical exam reveals a patient that is hyper-reflexive with a non-tender symmetrically enlarged thyroid gland. You order thyroid function tests for workup. What thyroid function values are most expected?