Deck 50: Steroid and Thyroid Hormones

Question 1

A 45-year-old woman was being regularly reviewed in primary and secondary care because of a 5-year history of type 2 diabetes that had required early insulin treatment, refractory hypertension, and subsequent chronic kidney disease. She had previously described other symptoms, including weight gain, bruising, flushes, and low mood, all of which had been attributed to obesity and menopause. She was not taking any glucocorticoids. After presenting to her local emergency department with a Colles' fracture after a low impact fall, she was referred to the endocrinology department for suspected Cushing syndrome. Analysis for which of the following would be most useful in confirming the initial diagnosis?

A) decreased plasma levels of thyroid-stimulating hormone
B) increased levels of plasma ACTH
C) increased urine T₃
D) reduced free plasma testosterone
E) reduced urine cortisol

Answer 1

B
EXPLANATION: The primary symptoms of Cushing syndrome result from the tissues being exposed to high levels of cortisol for too long. The most common cause of Cushing syndrome is a pituitary adenoma that secretes excess amounts of ACTH. ACTH stimulates the adrenal cortex to synthesize the glucocorticoids, primarily cortisol. Therefore, measurement of elevated plasma ACTH levels can indicate Cushing syndrome. Because ACTH induces cortisol production one would expect to see elevated urinary cortisol in addition to the elevated plasma ACTH.

Question 2

A 27-year-old woman presented to the ER complaining of nausea and vomiting for 1 week. She also reported 8 months of progressively worsening fatigue. The patient was previously very active as a ballet student, but for the past 8 months she stopped participating in ballet because of lack of energy and poor concentration. One week prior to admission, she developed nausea and had several episodes of vomiting which provoked her visit to the ER. She also reported a poor appetite for months and had lost 10 lb. Physical examination showed dryness and darkening of the skin in several areas. She repeatedly denied purposefully restricting food intake or binging and purging behaviors. There was no abdominal pain, diarrhea, fevers, dysuria, or headache. As the attending physician you suspect this patient is exhibiting signs of Addison disease. Testing for which of the following would be most useful in your diagnosis?

A) decreased plasma estrogen
B) decreased urinary cortisol
C) increased plasma ACTH
D) increased plasma aldosterone
E) increased plasma cortisol

Answer 2

B
EXPLANATION: Addison disease is characterized by general malaise and debility, irritability of the stomach, and hyperpigmentation. The disease results from a primary failure of the adrenal cortex to synthesize and secrete glucocorticoid (cortisol) and mineralocorticoid (aldosterone) hormones. Currently, 70% to 90% of cases of Addison disease are the result of autoimmune adrenalitis and frequently manifests in patients with other immunological and autoimmune disorders. Addison disease frequency is higher in females than males and is usually diagnosed between 30 and 50 years of age.

Question 3

A 45-year-old woman is being examined by her physician because she is concerned about her weight gain, fatigue, muscle weakness, and thinning hair. Physical examination shows a "buffalo hump," facial hirsutism, and red striae in abdominal and underarm areas. She indicates that she is not on any medication and there is no significant past history or family history. Laboratory studies show an elevated fasting blood glucose (11 mmol/L: 198 mg/dL) and a 24-hour urinary cortisol of 2276 nmol/24 h. These signs and symptoms are most likely the result of which of the following?

A) Addison disease
B) Cushing syndrome
C) Graves disease
D) hyperthyroidism
E) pituitary adenoma

Answer 3

B
EXPLANATION: Cushing syndrome describes the clinical consequences of chronic exposure to excess glucocorticoid irrespective of the underlying cause. Cushing syndrome may mimic common conditions such as obesity, poorly controlled diabetes, and hypertension, which progress over time and often coexist in patients with metabolic syndrome. The characteristic features of Cushing syndrome are psychiatric disturbances (depression, mania, and psychoses), central obesity, hypertension, diabetes, moon-shaped face, thin fragile skin, easy bruising, and purple striae (stretch marks). In addition, Cushing syndrome patients manifest with gonadal dysfunction that is characteristic of hyperandrogenism with excess body and facial hair (hirsutism) and acne. The most common symptoms that lead to a diagnosis of Cushing syndrome are weight gain, depression, subjective muscle weakness, and headache.

Question 4

A 63-year-old woman presented with increasing darkening of the skin, dizziness, easy fatigability, nausea with occasional vomiting, and progressive weight loss over 8 months prior to presentation. Physical examination showed a pulse of 106 bpm, supine blood pressure was 100/60 mm Hg and 70/40 mm Hg on sitting. She could not stand on account of severe postural dizziness. Radiological diagnostic tests included an abdominal ultrasound showing normal liver, spleen, pancreas, and pelvic organs. However, the left kidney was not outlined. A CT scan of the abdomen showed a nonenhancing oval-shaped left suprarenal mass with calcification. The signs and symptom in this patient are most likely the result of which of the following?

A) Addison disease
B) Cushing syndrome
C) Graves disease
D) hyperthyroidism
E) pituitary adenoma

Question 5

Which of the following processes is induced in males in response to the synthesis and release of follicle-stimulating hormone (FSH)?

A) FSH is a female-specific hormone and thus does not exert effects in males
B) growth arrest of spermatogonia to ensure their proper level of maturation
C) stimulation of adrenal steroidogenesis
D) stimulation of spermatogenesis
E) testosterone production and secretion

Question 6

Congenital adrenal hyperplasia, resulting from 21-hydroxylase (CYP21A2) deficiencies, is divided into 3 distinct clinical forms. The most severe enzyme-impairing mutations result in the saltlosing form. Females with this form of the disease present at birth due to ambiguity in the external genitalia. The physiological effect of salt losing is due to which of the following hormone defects?

A) cortisol production is negligible resulting in increased ACTH release from the pituitary
B) cortisol production is negligible due to loss of ACTH control of hypothalamic responses
C) the adrenal cortex compensates for loss of CYP21A2 by producing excess aldosterone
D) the adrenal cortex compensates for loss of CYP21A2 by producing no androstenedione
E) there is an associated dysregulation of androgen synthesis which normally controls aldosterone synthesis

Question 7

Which of the following is true with respect to the actions of the mineralocorticoids?

A) decrease carbohydrate metabolism
B) increase appearance of the secondary sex characteristics
C) increase synthesis of androgens
D) regulate aldosterone secretion
E) regulate sodium retention by the kidneys

Question 8

A 32-year-old woman is diagnosed with hypertension, hypernatremia, hypokalemia, and alkalosis. Measurements of plasma glucocorticoid levels show them to be within the normal range; however, renin and angiotensin II levels are suppressed. Ultrasound indicates the possible existence of an adrenal cortical mass. These symptoms are likely due to excess production of which of the following hormones?

A) aldosterone
B) androstenedione
C) dehydroepiandrosterone (DHEA)
D) estradiol
E) testosterone

Question 9

Steroid hormones interact with specific receptors within target cells. The steroid-receptor complexes then regulate the rate of which of the following intracellular processes?

A) posttranscriptional processing of specific mRNAs
B) posttranslational processing of specific proteins
C) replication of DNA
D) transcription of specific genes
E) translation of specific mRNAs

Question 10

A baby girl is born with ambiguous genitalia and diagnosed with severe classical congenital deficiency of adrenal 21-hydroxylase enzyme. Without any treatment, which of the following would you expect in the girl's future?

A) delayed puberty
B) hypernatremia
C) hypopigmentation
D) salt-wasting crises
E) tall stature

Question 11

High-dose glucocorticoid therapy for treatment
Of rheumatoid arthritis remains highly controversial. It is widely agreed that it is highly effective in controlling acute rheumatoid inflammation, but it may also result in significant adverse effects. Complications of high-dose glucocorticoid therapy include which of the following?

A) excessive growth in children and acromegaly in adults
B) hyperkalemia
C) hyponatremia
D) suppression of the hypothalamic-pituitaryadrenal axis
E) volume depletion

Question 12

A 4-year-old child with signs of precocious (earlyonset) puberty is brought to a clinic for evaluation and found to have a congenital deficiency of 21-hydroxylase. Feedback inhibition of the pituitary gland is lost and excess ACTH is secreted. As
A result, which of the following happens?

A) adrenal cortical atrophy occurs
B) adrenal medullary hypertrophy occurs
C) excess cortisol is released
D) precursors to cortisol synthesis increase
E) serum cholesterol falls dramatically

Question 13

A 35-year-old weightlifter who has been injecting testosterone for muscle mass augmentation is evaluated for sterility and found to have an extremely low sperm count. Which of the following is an effect of testosterone and contributes to the mentioned sterility?

A) activation of inhibin
B) feedback activation of leptin
C) feedback inhibition of GnRH
D) inhibition of seminal prostaglandins
E) lowered core temperature

Question 14

A 40-year-old woman complains of chronic fatigue, aching muscles, and general weakness. Physical examination reveals a modest weight gain, dry skin, and slow reflexes. Laboratory findings include TSH: >10 mU/L (normal range 0.5-5 mU/L), free T4: low to normal. Which of the following is the most likely explanation?

A) hyperthyroidism due to autoimmune thyroid disease
B) hyperthyroidism due to iodine excess
C) hyperthyroidism secondary to a hypothalamicpituitary defect
D) hypothyroidism due to autoimmune thyroid disease
E) hypothyroidism secondary to a hypothalamicpituitary defect

Question 15

A newly wed 23-year-old woman and her 28-yearold husband are evaluated for infertility. They have
Been unable to conceive a child despite regular
Intercourse for the past 12 months. The first step
Of this couple's infertility workup is to determine
Whether ovulation occurs regularly. Which of the
Following hormones is directly responsible for
Ovulation?

A) estradiol
B) estriol
C) follicle-stimulating hormone (FSH)
D) inhibin
E) luteinizing hormone (LH)

Question 16

A baby girl is born with ambiguous genitalia and diagnosed with severe classical congenital deficiency of adrenal 21-hydroxylase enzyme. Without any treatment, which of the following would you expect in the girl's future?

A) delayed puberty
B) hypernatremia
C) hypopigmentation
D) salt-wasting crises
E) tall stature

Question 17

Cushing syndrome is characterized by rapid weight gain, particularly of the trunk and face with sparing of the limbs (central obesity). Another common sign is the growth of fat pads along the collar bone and on the back of the neck (buffalo hump) and a round face often referred to as a "moon face" and excessive "sweating." This disorder results from overproduction of which of the following hormones?

A) ACTH
B) aldosterone
C) growth hormone
D) progesterone
E) thyrotropin-releasing hormone (TRH)

Question 18

You are treating a 37-year-old female patient whose signs and symptoms lead you to suspect she is suffering from an endocrine disorder. You order a series of tests to aid in your diagnosis. A basic metabolic panel showed elevated sodium of 111 mmol/L (normal range 135-145), potassium 4.5 mmol/L, chloride 78 mmol/L, bicarbonate 23 mmol/L, glucose 85 mg/dL, and creatinine 0.7 mg/dL. Further testing showed serum osmolality at 234 mOsm/kg (normal range 275-295) and urine sodium less than 20 mmol/L consistent with severe hypovolemic hyponatremia. A random cortisol level was less than 0.2 μg/dL. The plasma ACTH level was elevated at 882 pg/dL (normal range 5-27). These test results most likely indicate the patient is suffering from which of the following disorders?

A) Addison disease
B) Cushing syndrome
C) Graves disease
D) hyperthyroidism
E) pituitary adenoma

Question 19

You are treating a 29-year-old woman who came to you complaining of a 3-month history of increased sweating and palpitations with weight loss of 15 lb. Physical examination shows she is nervous and agitated with an obvious, diffuse, nontender, smooth enlargement of her thyroid, over which a bruit could be heard. She had a fine tremor of her fingers and a resting pulse rate of 150/min. Laboratory studies indicate the elevated serum T₃ of 4.8 nmol/L (normal: 0.8-2.4) and a T₄ of 48 nmol/L (normal: 9-23). Measurement of her thyroid-stimulating hormone showed that it was low normal, 0.4 mU/L (normal 0.4-5 mU/L). The signs and symptoms exhibited by your patient most likely indicate she is suffering from which of the following?

A) Addison disease
B) Cushing syndrome
C) Graves disease
D) hyperthyroidism
E) pituitary adenoma

Question 20

Cells of the zona fasciculata of the adrenal cortex do not synthesize the potent mineralocorticoids because they lack expression of which of the following enzymes?

A) CYP11B1, 11β-hydroxylase
B) CYP11B2, aldosterone synthase
C) CYP17A1, 17α-hydroxylase, and 17,20-lyase
D) CYP19A1, aromatase
E) CYP21A2, 21-hydroxylase

Question 21

You are treating a patient whose symptoms lead you to suspect that he is suffering from Cushing syndrome. Testing for which of the following would aid in your diagnosis in this patient?

A) decreased plasma T₃
B) decreased urinary cortisol
C) elevated plasma ACTH
D) elevated plasma growth hormone
E) elevated urinary testosterone

Question 22

You are treating a patient whose symptoms lead you to suspect that she is suffering from Addison disease. Testing for which of the following would aid in your diagnosis in this patient?

A) decreased plasma glucose
B) decreased plasma potassium
C) decreased plasma sodium
D) elevated plasma bicarbonate
E) elevated urinary cortisol

Question 23

A 2-month-old infant girl with a history of persistent physiological jaundice following birth is now reported by her parents to sleep excessively and display little activity. Physical examination reveals abnormal deep tendon reflexes, hypothermia, and muscular hypotonia. Based on this information, which of the following would be the best therapy for her condition?

A) antibiotics
B) growth hormone
C) thiamine
D) thyroxine
E) vitamin D

Question 24

During a routine physical examination, a 16-yearold adolescent boy is found to have only minimal secondary sexual development, gynecomastia, and a tall, eunuchoid habitus. A chromosomal determination on this individual would most likely reveal which of the following?

A) 45, XO
B) 45, YO
C) 46, XX
D) 46, XY
E) 47, XXY

Question 25

A 38-year-old woman has experienced the gradual onset of a goiter. Serum T4 and T3 are within the reference range and thyroid-stimulating hormone (TSH) is slightly increased. Serum antithyroid peroxidase (antimicrosomal) antibodies are detected
But there are no TSH receptor antibodies. Which of the following is the most likely diagnosis?

A) chronic autoimmune thyroiditis
B) Graves disease
C) primary atrophy of the thyroid
D) Riedel struma
E) subacute thyroiditis

Question 26

All steroid hormone receptors share several structural similarities including the DNA-binding domain. The DNA-binding domain of the steroid hormones is known as which of the following?

A) cI repressor
B) Cro dimer operator complex
C) kinase
D) phosphotyrosine
E) zinc finger

Question 27

A 20-year-old man with type 2 diabetes awakens at 3:00 am after 5 hours of sleep feeling queasy and light-headed. He tests his serum glucose and finds that it is 49 mg/dL. In response to his hypoglycemia, cortisol is secreted by the adrenal cortex and induces the synthesis of which of the following enzymes in the adrenal medulla?

A) acetyl-CoA carboxylase
B) homocysteine methyltransferase
C) methionine adenosyltransferase
D) methylmalonyl-CoA racemase
E) phenylethanolamineN-methyltransferase, PNMT

Question 28

Glucocorticoids enhance the expression of specific genes by binding to glucocorticoid receptors, resulting in which of the following?

A) activation of GTP-binding protein
B) activation of MYC
C) activation of receptor tyrosine kinase
D) binding of the receptor-steroid complex to DNA
E) formation of a JUN-FOS (AP1) complex

Question 29

Receptors for all of the members of the steroid hormone family share which of the following features?

A) calcium-mediated intracellular effects
B) GTP-binding proteins
C) mitochondrial membrane association
D) plasma membrane association
E) zinc-containing DNA-binding domains

Question 30

The synthetic glucocorticoid, dexamethasone, binds to, and activates the glucocorticoid receptor. Which of the following activities of the glucocorticoid receptor is the most likely even after dexamethasone is eliminated from the body?

A) catalyzes formation of stable tyrosine-phosphate bonds
B) competes with β-arrestin for binding to adrenergic receptors
C) couples to G-proteins with low intrinsic GTPase activity
D) depletes cellular stores of glutathione
E) induces proteins that remain functional after the drug is eliminated

Question 31

A 47-day-old newborn has ambiguous genitalia. Serum sodium concentration is 120 mEq/L and serum potassium concentration is 7 mEq/L. Chromosome analysis shows a 46,XX karyotype. This infant most likely has a defect in the synthesis of which of the following hormones?

A) ACTH
B) cortisol
C) estradiol
D) progesterone
E) testosterone

Question 32

A full-term newborn has ambiguous genitalia. Ultrasonographic examination shows a uterus and bilateral uterine tubes. Chromosomal analysis shows a 46,XX karyotype. Which of the following most likely occurred during development?

A) decreased 5α-reductase activity in cells of the genital tubercle
B) deficient activity of 21-hydroxylase in cells of the adrenal cortex
C) failure of formation of the urogenital folds
D) increased atresia of primordial follicles
E) increased numbers of Sertoli cells

Question 33

After cortisol interacts with its receptor, which of the following events is most likely occur?

A) activation of adenylate cyclase by the receptor
B) autophosphorylation of tyrosine residues in the receptor
C) endocytosis of the hormone-receptor complex
D) interaction of the receptor with a G-protein
E) translocation of the hormone-receptor complex to the nucleus