Preguntas y Respuestas 4

Preguntas y Respuestas 4A 33-year-old woman gives birth to a baby girl. The next day, she begins to bleed from her vagina and from venipuncture sites. Laboratory studies demonstrate decreased platelets, prolonged prothrombin time (PT) and partial thromboplastin time (PTT), and increased fibrin split products. These features are most consistent with which of the following?

A. Disseminated intravascular coagulationB. Hemophilia AC. Severe liver diseaseD. Vitamin K deficiencyE. Von Willebrand's disease

The correct answer is A. The patient is experiencing disseminated intravascular coagulation (DIC), a feared, and often life-threatening complication of many other disorders, including amniotic fluid embolism, infections (particularly gram-negative sepsis), malignancy, and major trauma. The diagnosis is suspected when both a decrease in platelets and a prolongation of PT and PTT times are observed. The observed hematologic abnormalities are due to consumption of platelets and clotting factors, caused by extensive microclot formation with accompanying fibrinolysis (reflected by the increased fibrin split products). The D-dimer assay measures cross-linked fibrin derivatives, and is a specific test for fibrin degradation products.

A 40-year old man complains of increasing difficulty in swallowing over the past 3 years. He reports a feeling of pressure in his chest occurring 2-3 seconds after swallowing a solid bolus. He also experiences regurgitation of undigested food eaten hours previously. A radiograph taken after swallowing barium shows a distended esophageal body with a smooth tapering at the lower esophageal sphincter. Manometry shows the absence of esophageal peristalsis with swallowing and a lower esophageal sphincter that fails to relax. What is the most likely diagnosis?

A. AchalasiaB. Diffuse esophageal spasmC. Incompetent lower esophageal sphincterD. Oropharyngeal dysphagiaE. Scleroderma

The correct answer is A. Achalasia is an acquired esophageal motility disorder that slowly develops. The motility is abnormal due to the loss of inhibitory enteric neurons of the esophageal body and lower esophageal sphincter. Both vasoactive intestinal peptide and nitric oxide function as inhibitory neurotransmitters here, and the presence of both is decreased in achalasia. Radiographs typically show a dilated esophagus that tapers at the lower esophageal sphincter, producing a so-called "bird's beak." Because of the poor motility, ingested food is regurgitated and can lead to aspiration symptoms. Heartburn can occur due to production of lactic acid in the esophagus as the retained ingestate is fermented. Manometric demonstration of absent peristalsis in the esophageal body and poor relaxation of the lower esophageal sphincter with a swallow confirm the diagnosis.

A 29-year-old woman with a history of irregular menses becomes amenorrheic. She had no problems conceiving her first child at the age of 23, but she has been trying unsuccessfully to become pregnant for the past two years. She also notes a weight gain of about 3 kg, increasing fatigue, puffy face and marked cold intolerance. A complete blood count (CBC) reveals a Hb of 11.1 and an MCV of 90. Physical exam reveals a moderate-sized diffuse enlargement of the thyroid gland. Which of the following thyroid profiles would most likely be seen in this woman?

A. Low T3, low T4, high TSH B. Low T3, low T4, low TSH C. Low T3, high T4, low TSH D. High T3, low T4, low TSH E. High T3, high T4, low TSH

The correct answer is A. This woman is experiencing signs and symptoms of hypothyroidism, the most common cause of which is chronic thyroiditis, or Hashimoto's thyroiditis. It is an autoimmune disorder, mostly affecting women, in which antithyroid antibodies are produced. The immune response results in autoimmune destruction of the thyroid gland, rendering it less able to produce thyroid hormone, causing hypothyroidism. Some other symptoms of hypothyroidism are weakness, fatigue, coarse hair, constipation, hoarseness, and hearing loss. Since the thyroid cannot produce thyroid hormone, both T3 and T4 would be low. In trying to compensate for low thyroid hormone levels, the pituitary gland releases excess TSH to stimulate the thyroid gland to make more thyroid hormone.A 74-year-old woman, in otherwise good health, tripped and injured her right leg 2 days previously and has been bedridden since the accident. Two hours ago, she became delirious. On physical examination, her temperature is 99 F, blood pressure is 120/70 mm Hg, heart rate is 110, and respiratory rate is 32. Pulse oximetry shows an oxygen saturation of 80%, and a chest x-ray film is normal. Which of the following is the most likely diagnosis?

A. Acute cerebral hemorrhage B. Acute cerebral infarction C. Myocardial infarction D. Pulmonary infarction E. Pulmonary thromboembolism Explanation: The correct answer is E. Hip fracture and prolonged bed rest are classic risk factors for the development of pulmonary thromboemboli (PE). Common clinical manifestations of PE are hypoxia (due to ventilation/perfusion mismatch) despite a normal chest x-ray, tachycardia, and delirium in older patients.

A 65-year-old man with hyperlucent lung fields develops extreme shortness of breath over a period of about 15 minutes. Chest x-ray shows a shift of the mediastinum to the right, and the lung field on the left appears even more hyperlucent than before, with the exception of a white shadow near the heart border. Which of the following is the most probable cause of the patient's current problem?

A. Bronchogenic carcinoma B. Pleural effusion C. Pulmonary embolism D. Rupture of an emphysematous bulla E. Tuberculosis

Explanation: The correct answer is D. The patient's initial hyperlucent lung fields strongly suggest the presence of emphysema. The radiologic findings after the increase in shortness of breath are consistent with free air in the chest, which has collapsed the left lung and caused a shift in the location of the mediastinum. Such air might have been introduced by rupture of a bulla. Small pneumothoraces are usually well tolerated, but larger ones may require decompression (the needle from a syringe is sometimes used), or even surgical correction if bullae continue to leak air.Which of the following conditions would mostly likely be associated with chronic gastritis (Type A) resulting from autoimmune destruction of parietal cells?

A. Decreased growth of luminal bacteria B. Decreased likelihood of developing gastric carcinoma C. Decreased plasma concentration of gastrin D. Increased production of macrocytic red blood cells E. Increased secretion of pancreatic bicarbonate

Explanation: The correct answer is D. Autoimmune destruction of parietal cells would lead to decreased secretion of gastric acid and intrinsic factor. The diminished availability of intrinsic factor would result in poor absorption of dietary vitamin B12. Over time, the vitamin B12 deficiency could lead to pernicious anemia, which is characterized by increased production of macrocytes (megaloblasts) by the bone marrow.

A 55-year-old hypertensive man develops sudden onset of excruciating pain beginning in the anterior chest, and then radiating to the back. Over the next 2 hours, the pain moves downward toward the abdomen. Which of the following is the most probable diagnosis?

A. Aortic dissection B. Aortic valve stenosis C. Atherosclerotic aneurysm D. Myocardial infarction E. Syphilitic aneurysm

Explanation: The correct answer is A. This patient has an aortic dissection (formerly called dissecting aneurysm), a potentially fatal condition that is too often confused clinically with myocardial infarction. The most important clinical clue is that the pain shifts with time. Non-invasive techniques such as transesophageal echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) are increasingly useful in making this diagnosis.

A 30-year old male complains of fatigue and diffuse skeletal pain. He has a history of Crohn's disease, which led to resection of the terminal ileum 3 years previously. Steatorrhea and diarrhea have continued since the surgery. Laboratory tests show that serum calcium is 7.5 mg/dL, serum phosphate is 2.5 mg/dL, and serum parathyroid hormone (N-terminal) is 750 pg/mL. Which of the following is the most likely cause of these findings?

A. Osteoporosis B. Paget's disease C. Primary hypoparathyroidism D. Renal failure E. Vitamin D deficiency

Explanation: The correct answer is E. Whenever serum calcium and phosphate are both decreased, vitamin D deficiency should be considered. In this case, the vitamin D deficiency is due to fat malabsorption, including the fat-soluble vitamin D, subsequent to ileal resection. If more than 100 cm of the ileum are removed, primary bile acid production by the liver cannot keep up with bile salt loss in the stool. The total bile salt pool decreases and fat absorption, including the fat-soluble vitamins is poor.