Platelet disorders — MCQs

A previously healthy 17-year-old boy is brought to the emergency department by his mother for further evaluation after elective removal of his wisdom teeth. During the procedure, the patient had persistent bleeding from the teeth's surrounding gums. Multiple gauze packs were applied with minimal effect. The patient has a history of easy bruising. The mother says her brother had similar problems when his wisdom teeth were removed, and that he also has a history of easy bruising and joint swelling. The patient takes no medications. His temperature is 37°C (98.6°F), pulse is 90/min, and blood pressure is 108/74 mm Hg. Laboratory studies show: Hematocrit 35% Leukocyte count 8,500/mm3 Platelet count 160,000/mm3 Prothrombin time 15 sec Partial thromboplastin time 60 sec Bleeding time 6 min Fibrin split products negative Serum Urea nitrogen 20 mg/dL Creatinine 1.0 mg/dL Bilirubin Total 1.0 mg/dL Direct 0.5 mg/dL Lactate dehydrogenase 90 U/L Peripheral blood smear shows normal-sized platelets. Which of the following is the most likely diagnosis?

A 34-year-old, previously healthy woman is admitted to the hospital with abdominal pain and bloody diarrhea. She reports consuming undercooked beef a day before the onset of her symptoms. Her medical history is unremarkable. Vital signs include: blood pressure 100/70 mm Hg, pulse rate 70/min, respiratory rate 16/min, and temperature 36.6℃ (97.9℉). Physical examination shows paleness, face and leg edema, and abdominal tenderness in the lower right quadrant. Laboratory investigation shows the following findings: Erythrocytes 3 x 106/mm3 Hemoglobin 9.4 g/dL Hematocrit 0.45 (45%) Corrected reticulocyte count 5.5% Platelet count 18,000/mm3 Leukocytes 11,750/mm3 Total bilirubin 2.33 mg/dL (39.8 µmol/L) Direct bilirubin 0.2 mg/dL (3.4 µmol/L) Serum creatinine 4.5 mg/dL (397.8 µmol/L) Blood urea nitrogen 35.4 mg/dL (12.6 mmol/L) E. coli O157: H7 was identified in the patient’s stool. Which toxin is likely responsible for her symptoms?

A 66-year-old woman presents to the emergency department complaining of palpitations. She says that she has been experiencing palpitations and lightheadedness for the past 6 months, but before this morning the episodes usually resolved on their own. The patient's medical history is significant for a transient ischemia attack 2 months ago, hypertension, and diabetes. She takes aspirin, metformin, and lisinopril. She states her grandfather died of a stroke, and her mom has a "blood disorder." An electrocardiogram is obtained that shows an irregularly irregular rhythm with rapid ventricular response, consistent with atrial fibrillation. She is given intravenous metoprolol, which resolves her symptoms. In addition to starting a beta-blocker for long-term management, the patient meets criteria for anticoagulation. Both unfractionated heparin and warfarin are started. Five days later, the patient begins complaining of pain and swelling of her left lower extremity. A Doppler ultrasound reveals thrombosis in her left popliteal and tibial veins. A complete blood count is obtained that shows a decrease in platelet count from 245,000/mm^3 to 90,000/mm^3. Coagulation studies are shown below: Prothrombin time (PT): 15 seconds Partial thromboplastin time (PTT): 37 seconds Bleeding time: 14 minutes Which of the following is the most likely diagnosis?

A 3-year-old girl is brought to her pediatrician because of a nosebleed that will not stop. Her parents say that she started having a nosebleed about 1 hour prior to presentation. Since then they have not been able to stop the bleeding. Her past medical history is remarkable for asthma, and she has a cousin who has been diagnosed with hemophilia. Physical exam reveals diffuse petechiae and purpura. A panel of bleeding tests are obtained with the following results: Bleeding time: 11 minutes Prothrombin time: 14 seconds Partial thromboplastin time: 32 seconds Platelet count: 195,000/mm^3 Peripheral blood smear shows normal cell morphology. Which of the following characteristics is most likely true about this patient?

Seven days after undergoing bilateral total knee arthroplasty, a 65-year-old man comes to the physician with a dark discoloration and blisters on his abdomen. Current medications include simvastatin, aspirin, and low molecular weight heparin. His vital signs are within normal limits. Examination of the skin shows multiple coalescing blisters with areas of necrosis around the umbilicus. Laboratory studies show a platelet count of 32,000/mm3. Which of the following is the most likely underlying cause of this patient's symptoms?

A previously healthy 40-year-old woman comes to the physician because of a 3-day history of fever, headaches, and fatigue. She also reports a persistent tingling sensation in her right hand and numbness in her right arm that started this morning. Physical examination shows pallor, mild scleral icterus, and petechiae on her forearms and legs. On mental status examination, she appears confused and is only oriented to person. Laboratory studies show: Hemoglobin 11.1 g/dL Platelet count 39,500/mm3 Bleeding time 9 minutes Prothrombin time 14 seconds Partial thromboplastin time 35 seconds Serum Creatinine 1.7 mg/dL Total bilirubin 2.1 mg/dL A peripheral blood smear shows fragmented erythrocytes. Which of the following is the most likely underlying cause of this patient's condition?

A 2-year-old boy had increased bleeding during a circumcision. His birth and delivery were uncomplicated, and his mother had no issues with prolonged bleeding during labor. Of note, his maternal grandfather has a history of bleeding complications. The boy's vital signs are stable and physical examination is notable for scattered bruises on his lower extremities. The lab results are as follows: Hemoglobin 12.8 gm % Hematocrit 35.4% WBC 8400/mm3 Platelets 215 x 109/L PT 14 s PTT 78 s What is the most likely diagnosis?

An 8-year-old boy is brought to the pediatric emergency department by his parents with a complaint of abdominal pain and diarrhea for the past week. He states that for the past two days, he has noticed blood in his stool. His parents note that they attended a neighbor’s barbecue last weekend, but otherwise have not eaten any new foods or changed their usual diet. The patient is admitted to the hospital unit for further work-up. The provider team finds that the patient’s blood is positive for Shiga-like toxin and notes the following lab values: creatinine of 4.2 mg/dL, platelet count of 50,000/mm^3, and hemoglobin of 6.0 g/dL. Which of the following additional lab findings would be consistent with the diagnosis?

A 61-year-old man presents to the primary care clinic to establish care. He has not seen a physician for many years. He has no complaints or concerns but, on further questioning, does have some vague abdominal discomfort. He has no known past medical history and takes no medications. His social history is notable for injecting heroin throughout his late-teens and 20s, but he has been clean and sober for over a decade. At the clinic, the vital signs include: heart rate 90/min, respiratory rate 17/min, blood pressure 110/65 mm Hg, and temperature 37.0°C (98.6°F). The physical exam shows a slightly distended abdomen. The laboratory studies are notable for a platelet count of 77,000/uL and an international normalized ratio (INR) of 1.7. Which of the following is the next best step in the diagnosis of this patient?

A 64-year-old man comes to the emergency department complaining of fatigue and abdominal distension. He has a remote history of intravenous drug use. Vital signs include a normal temperature, blood pressure of 120/80 mm Hg, and a pulse of 75/min. Physical examination reveals jaundice and a firm liver. Abdominal ultrasonography shows liver surface nodularity, moderate splenomegaly, and increased diameter of the portal vein. Complete blood count of the patient is shown: Hemoglobin 14 g/dL Mean corpuscular volume 90/μm3 Mean corpuscular hemoglobin 30 pg/cell Mean corpuscular hemoglobin concentration 34% Leukocyte count 7,000/mm3 Platelet count 50,000/mm3 Which of the following best represents the mechanism of low platelet count in this patient?