USMLE题库Endocrinology1-10

1、Endocrinology题库Q 1A 50-year-old male presents to the emergency room with a sudden severe headache, double vision, and bitemporal hemianopsia. He says that hes had decreased libido and mild headaches for a few months. As you are presenting to your attending，hedevelops cardiovascular collapse and dies

2、，despite aggressive resuscitation. Autopsy will most likely reveal which of the following?A. Rupture of berry aneurysmB. Pituitary hemorrhage C. Pulmonary embolismD. Ischemic necrosis of pituitary E. Acute congestive glaucoma F. Temporal arteritisA 1: Correct answer: BThe patient described in the vi

3、gnette most likely had pituitary apoplexy, which is acute bleeding in to a preexisting pituitary adenoma. Pituitary apoplexy is a medical emergency; without treatment, prognosis is poor. Symptoms will be bimodal; acute and chronic. The long-standing symptoms of a pituitary tumor will be present for

4、months, as with this mans headache and decreased libido; accompanying these chronic symptoms will be an acute presentation, as with the severe headache and visual disturbances in this patient.Signs of meningeal irritation can also be seen in pituitary apoplexy, mimicking a subarachnoid hemorrhage. A

5、 careful physical exam can differentiate a subarachnoid hemorrhage from a sellar mass with suprasellar extension (pituitary tumor) by the presence of bitemporal hemianopsia, present only in the latter. Patients suffering from pituitary apoplexy develop cardiovascular collapse because ACTH deficiency

6、 leads to adrenocortical insufficiency. An urgent neurosurgical consultation and treatment with glucocorticoids are required.(Choice A) The rupture of berry aneurysm can present similarly to pituitary apoplexy, including signs of meningeal irritation and cranial nerve palsy. As discussed previously,

7、 these conditions can be differentiated by bitemporal hemianopsia, which is specific to pituitary lesions. An MRI of the brain will be very sensitive in diagnosing either condition.(Choice C) Pulmonary emboli usually cause shortness of breath, chest pain, and hypotension. Headache and diplopia are n

8、ot the presenting features of pulmonary embolism.(Choice D) Ischemic necrosis of the pituitary is also known as Sheehan syndrome, which typically affects postpartum women. Acute headaches and visual field defects do not occur; rather, most patients with Sheehan syndrome present indolently with a fai

9、lure to lactate.(Choice E) Acute congestive glaucoma will cause eye pain, periorbital headaches, eye redness, and decreased vision-but not diplopia. Circulatory collapse does not occur.(Choice F) The characteristic presentation of temporal arteritis is headaches, jaw claudication, and-if not treated

10、vision loss due to ischemic optic neuropathy. The presentation is not catastrophic as seen in the patient described in the vignette.Q 2A 60-year-old man comes to the physician with difficulty climbing stairs and dyspnea on exertion. He also complains of gaining 15 kg (33 lb) over the last several mo

11、nths. Physical examination reveals darkening of his skin and proximal muscle weakness. Chest x-ray shows a lung mass. Laboratory studies reveal elevated serum cortisol and adrenocorticotropic hormone levels. Which of the following additional studies would be the most helpful for establishing the dia

12、gnosis?A. Magnetic resonance imaging of the brainB. Dexamethasone suppression testC. Serum thyroid-stimulating hormone levelsD. Adrenocorticotropic hormone stimulation test E. Serum cortisol levels at 8:00 AMA 2Correct answer: BThe workup of endogenous Cushing syndrome involves measuring adrenocorti

13、cotropic hormone (ACTH) and cortisol levels as well as dexamethasone suppression testing. Cortisol levels are elevated in all patients with Cushing syndrome; ACTH levels can be high or low depending on the etiology. Primary adrenal disease presents with suppressed ACTH levels due to intact hypothala

14、mic-pituitary feedback inhibition. However, Cushing syndrome caused by a pituitary adenoma or ectopic ACTH secretion will present with elevated ACTH levels. High-dose dexamethasone suppression testing can help distinguish between these 2 possibilities.Patients with ACTH hypersecretion from a pituita

15、ry adenoma are only relatively resistant to glucocorticoid feedback inhibition. Thus, high-dose dexamethasone suppression testing will cause a reduction in cortisol and ACTH levels in these patients. In contrast, most nonpituitary tumors associated with ectopic ACTH production are completely resista

16、nt to feedback inhibition. Because this patient has elevated ACTH levels, dexamethasone suppression testing would be the best next step to further delineate the cause of his Cushing syndrome.(Choice A) Imaging studies such as MRI or CT scan are not usually performed in the initial evaluation of most

17、 endocrinologic disorders, including Cushing syndrome. Biochemical investigation comes first in the workup before any imaging as brain MRI will show small masslike lesions 5%-10% of the time even in normal subjects (incidentalomas).(Choice C) A diagnosis of hypothyroidism would not explain this pati

18、ents elevated cortisol and ACTH levels.(Choice D) The ACTH stimulation test is used in the evaluation of adrenocortical insufficiency, not adrenocortical excess.(Choice E) In normal individuals, serum cortisol levels are highest early in the morning and drop significantly in the evening hours. Howev

19、er, in Cushing syndrome, this normal circadian rhythm is lost. Thus, measurement of cortisol levels in the evening is more sensitive and specific for Cushing syndrome screening, since levels are normally the lowest at this time.Q 3A 32-year-old Caucasian male comes to your office complaining of visu

20、al problems. He has had several near-misses” in his car lately, being nearly hit by cars coming fyom both the right and the left He also admits to having headaches that respond to acetaminophen. Which of the following hormones is most likely elevated in this patient?A.Growth hormoneB.Adrenocortical-

21、stimulating hormoneC.Thyroid-stimulating hormoneD.ProlactinE.Follicle-stimulating hormoneA 3Correct answer: DThis patients symptoms should immediately make you suspect a pituitary tumor-he has a headache accompanied by loss of peripheral vision. Compression of the optic chiasm by suprasellar extensi

22、on of pituitary tumors causes the characteristic bitemporal hemianopsia. His headache is likely caused by an increase in intracranial pressure, caused by mass effect of the tumor.Pituitary tumors typically arise from one of the five major cell types of the anterior pituitary gland. Approximately 60%

23、 of pituitary tumors are prolactin-secreting adenomas. Prolactin is a 199 amino acid peptide hormone secreted from lactotrophs of the pituitary gland. The primary physiologic action of prolactin is preparation of the breasts for milk production/lactation in the postpartum period. Prolactinomas stimu

24、late inappropriate milk production in nonpostpartum females (galactorrhea). Prolactin also suppresses gonadotrophin-releasing hormone (GnRH) production from the hypothalamus, which causes decreased libido, amenorrhea, and infertility. Pituitary tumors can grow beyond the limits of the sella turcica,

25、 causing compression and erosion of surrounding structures. If the pituitary tumor grows superiorly, it erodes the optic chiasm; laterally, it invades the cavernous sinus; inferiorly, it grows into the sphenoid sinus. A growing pituitary tumor can also compress normal pituitary cells, causing hypopi

26、tuitarism.(Choice A) Somatotroph adenomas increase growth hormone production and cause acromegaly in adults and gigantism in children.(Choice B) Corticotroph adenomas produce adrenocortical-stimulating hormone, (ACTH), which causes Cushing disease.(Choice C) Thyrotroph adenomas produce thyroid-stimu

27、lating hormone (TSH), leading to thyrotoxicosis. Thyrotroph adenomas are very uncommon.(Choice E) Gonadotroph adenomas usually do not produce intact follicle-stimulating hormone (FSH) or luteinizing hormone (LH). These tumors typically over produce alpha subunits of these glycoprotein hormones, and

28、present with mass effects and hypogonadism. Most nonsecretory adenomas arise from the gonadotrophs. These tumors tend to grow slowly.The anterior pituitary gland is composed of five major types of cells. Pituitary tumors typically arise from one of these cell types.Q 4A 53-year-old woman presents to

29、 your office for routine check-up. She has no present complaints. Her past medical history is significant for osteoarthritis of the right knee. Her mother suffered from hypertension and was diagnosed with breast cancer at 68 years old, which caused the womans death four years later. The patients fat

30、her had diabetes mellitus and died in a motor accident. Todays blood pressure is 140/85 mmHg, and heart rate is 80/min. Physical examination, including breast examination, is normal. Laboratory testing is significant for a blood glucose level of 160 mg/dL. This patient will most likely die of which

31、of the following causes?A. StrokeB. Myocardial infarction C. Breast cancerD. Hyperosmolar nonketotic coma E. Renal failureA 4Correct answer: BCardiovascular mortality is increased by two to three-fold in patients with diabetes mellitus. Several studies have shown that diabetes is the strongest risk

32、factor for coronary heart disease. Approximately 40-50% of patients with diabetes mellitus die secondary to coronary artery disease. For a person with diabetes, the risk of dying from ischemic heart disease exceeds the risk of dying from any of the other causes listed. Even in the absence of other m

33、ajor risk factors for ischemic heart diseasehypertension, hypercholesterolemia, and smokingthe relative risk of ischemic heart disease in diabetes is elevated.(Choice A) The risk of stroke is increased in patients with diabetes mellitus. Cerebrovascular accidents contribute to about 10% of mortality

34、 in patients with diabetes versus a 40-50% of mortality from cardiovascular disease.(Choice C) The risk of breast cancer is not increased in patients with diabetes mellitus. Although this patient does have a family history of breast cancer, her mother was at a relatively advanced age when this cance

35、r occurred.(Choice D) Diabetic ketoacidosis (DKA) and hyperosmolar coma are acute complications of diabetes mellitus. Hyperosmolar coma is mainly seen in type 2 diabetes mellitus. It is characterized by very high blood sugar levels without ketoacidosis. The mortality of a hyperosmolar coma is higher

36、 than DKA; however, very few patients with diabetes die due to DKA or hyperosmolar coma.(Choice E) Diabetes mellitus is the leading cause of end stage renal disease (ESRD), followed by hypertension. However, more than 50% of patients with ESRD die due to ischemic heart disease.Q 5A 24-year-old Cauca

37、sian female presents to your office two weeks after delivery. She is concerned because she has not yet lactated. She says that she knew she would lose weight and be tired after the baby was born, but she complains of excessive fatigue and has had significant weight loss. Thorough evaluation of this

38、patient reveals decreased serum T4 level and decreased 24-hour urine cortisol excretion. Which of the following pathologic processes is most likely responsible for this patients symptoms?A. Inflammation B. ApoplexyC.Ischemic necrosis D.Non-malignant infiltrationE. Malignant infiltrationA 5Correct an

39、swer: CThis patients description fits the classical description of Sheehans syndrome. High estrogen levels during pregnancy stimulate growth of the pituitary, causing it to both enlarge and become more vascular If significant hypotension occurs while the pituitary is still enlarged (the most common

40、cause is postpartum hemorrhage), ischemic necrosis of the pituitary occurs. A deficiency of multiple pituitary hormones (panhypopituitarism) follows this ischemia. Prolactin deficiency is one sequelae of the necrosis, which has important symptomatic and diagnostic significance. As prolactin is respo

41、nsible for milk secretion from the breast, its deficiency leads to failure to lactate-which can be emotionally devastating to women planning on breastfeeding. Patients suffering from Sheehan syndrome also commonly have hypothyroidism and hypocortisolism.(Choice A) Autoimmune hypophysitis (an inflamm

42、ation of the hypophysis, or pituitary) is a condition sometimes seen during late pregnancy or the early postpartum period. Both the anterior and posterior pituitary become inflamed. The presentation is acute with headaches, visual field defects and cortisol deficiency. For unknown reasons, cortisol

43、deficiency develops more commonly than other hormonal deficiencies. Failure of lactation due to prolactin deficiency is not common with lymphocytic hypophysitisi.e. when the hypophysis is infiltrated with many lymphocytes. Hypophysitis differs from Sheehan syndrome in the presence of visual field de

44、ficits and the acuity of presentation.(Choice B) Pituitary apoplexy describes hemorrhage into a preexisting pituitary adenoma. It is a medical emergency. The patient usually presents with acute, severe headache, ophthalmoplegia, and altered sensorium. A high index of suspicion is required. The patie

45、nts require urgent neurosurgical consultation and stress doses of glucocorticoids.(Choices D and E) Primary pituitary cancer is extremely rare, although the pituitary is prone to metastases due to its rich vascular supply. Non-malignant infiltrative lesions such as sarcoidosis and histocytosis X can

46、 also occur, mainly in the suprasellar region. These patients typically present with tumor massQ 6A 34-year-old Caucasian female presents to your office complaining of mood swings, difficulty concentrating, and a hand tremor that started only recently. She also admits to having discomfort in her nec

47、k. The discomfort radiates to her ears, particularly on swallowing. She ignored the neck and ear discomfort at first because she thought they might be related to flu-like symptoms that she had few weeks ago. Her blood pressure is 140/80 mmHg，and heart rate is 105/min. You proceed with a thyroid scan

48、 which shows a diffuse decrease in radioactive iodine uptake. Erythrocyte sedimentation rate (ESR) is 105 mm/Hr. Which of the following pathological changes in the thyroid gland is most consistent with the clinical scenario described?A. Follicular hyperplasia with tall cells forming intrafollicular

49、papillary projections B. Mononuclear, parenchymal infiltration with well-developed germinal centers C. Mixed, cellular infiltration with occasional multinucleate giant cells D. Extensive stromal fibrosis extending beyond the thyroid capsule E. Branching papillary structures with interspersed calcifi

50、ed bodiesA 6Correct answer: CThe clinical picture described in this vignette is indicative of subacute thyroiditis. Subacute granulomatous thyroiditis is also known as de Quervains thyroiditis or granulomatous thyroiditis. It is possibly caused by a viral infection. The patient has had a recent illn

51、ess, possibly viral, and also has various features of thyrotoxicosis, tenderness over the thyroid gland, increased ESR? and a markedly reduced radioactive iodine uptake. Thyrotoxicosis in subacute thryoiditis is caused by release of stored thyroid hormones secondary to thyroid inflammation; subacute

52、 thryoiditis does not cause excessive production of thyroid hormone, which is why iodine uptake is decreased.The involvement of thyroid gland in subacute thyroiditis can be patchy. Initial neutrophil infiltration predominance is followed by infiltration of lymphocytes, histiocytes, and multinucleate

53、d giant cells. The thyroid follicles become disrupted, and multinucleated giant cells surround the fragmented colloid. The thyrotoxic phase is followed by a hypothyroid phase for few months. Most patients eventually recover without any residual thyroid dysfunction. An antithyroid peroxidase antibody

54、 titer is not elevated in these patients.Most patients respond to non-steroidal anti-inflammatory drugs for thyroid pain and inflammation.(Choices A and E) Branching papillary structures with concentric calcifications (psammoma bodies) are typical of papillary thyroid cancer. Another characteristic

55、feature of papillary thyroid cancer is the ground-glass nucleus with intranuclear grooving. The tall cell variant of papillary thyroid cancer is characterized by follicular hyperplasia, lined by tall epithelial cells. This variant of papillary thyroid cancer is seen in older individuals and carries

56、a relatively worse prognosis when compared to well-differentiated papillary thyroid cancer.(Choice B) Diffuse mononuclear infiltration with formation of germinal centers is a very characteristic feature of chronic lymphocytic thyroiditis, also called Hashimotos thyroiditis. The infiltrate consists o

57、f lymphocytes and plasma cells. Patients with Hashimotofs thyroiditis present with thyroid enlargement (goiter) and/or hypothyroidism. Usually, the presentation of Hashimotos thyroiditis is chronic, with symptoms gradually worsening over several weeks or months. Hashimoto.s thyroiditis can be differ

58、entiated from other thyroid dysfunction by the following: a relatively normal erythrocyte sedimentation rate, features of hypothyroidism, a nontender thyroid gland with a rubbery texture, and high titers of antithyroid peroxidase autoantibody.(Choice D) Riedel thyroiditis is characterized by extensi

59、ve fibrosis involving the thyroid gland. The fibrosis can extend into surrounding structure.Q 7A 65-year-old man comes to the physician because of a non-healing ulcer on his right foot. His past medical history is significant for recurrent high blood glucose readings for the last several years, beca

60、use he has failed to comply with appropriate treatment. His BMI is 37 kg/m . Physical examination is significant for a bilateral symmetric decrease in vibration sensation over the feet and ankles. Which of the following is most likely to be associated with this patients condition? A.Pancreatic islet