A 67-year-old man is evaluated for exertional dyspnea. He recalls that 3 years ago he was told that he had anemia. In reviewing his records, you note that at that time his hemoglobin level was 9.5 g/dL and his hematocrit was 33% with an increased mean corpuscular volume (MCV); the remainder of his complete blood cell count was normal. On physical examination, he had conjunctival pallor, normal heart and lung findings, no lymphadenopathy, no hepatomegaly or splenomegaly, and no petechiae or ecchymoses. Diagnostic testing results are shown in Table 9.Q1. Which of the following is the most likely explanation for these findings?

A 67-year-old man is evaluated for exertional dyspnea. He recalls that 3 years ago he was told that he had anemia. In reviewing his records, you note that at that time his hemoglobin level was 9.5 g/dL and his hematocrit was 33% with an increased mean corpuscular volume (MCV); the remainder of his complete blood cell count was normal. On physical examination, he had conjunctival pallor, normal heart and lung findings, no lymphadenopathy, no hepatomegaly or splenomegaly, and no petechiae or ecchymoses. Diagnostic testing results are shown in Table 9.Q1. Which of the following is the most likely explanation for these findings?

A 62-year-old man with chronic atrial fibrillation has been treated with warfarin. He has no other chronic illnesses and is receiving no other medications long-term except for lipid-lowering agents. Results of his complete blood cell count and tests of renal and kidney function are normal. He checks his prothrombin time monthly and has kept the international normalized ratio (INR) within the therapeutic range (2-3) for the duration of his therapy with warfarin. He has heard about recent US Food and Drug Administration (FDA) approval of dabigatran, which requires no monitoring, and he would like a prescription for this new drug. Which of the following statements is true about the use of dabigatran in atrial fibrillation compared with the well-managed use of warfarin?

An 80-year-old man is admitted to the hospital after falling on an icy sidewalk and fracturing his hip. He undergoes open reduction and internal fixation of the fracture. At surgery, there does not appear to be any bone disease at the fracture site. The patient was previously asymptomatic. Physical examination findings are otherwise unremarkable. Serum protein electrophoresis and immunofixation show an IgM κ monoclonal protein (0.3 g/dL). The complete blood cell count and serum creatinine levels are normal. Skeletal survey shows no additional bone defects. Which of the following statements is true for this patient?

A 5-year-old white female has multiple bruises on her lower extremities and oral mucosal bleeding of 3 days' duration. Two weeks before these signs, she had a mild respiratory tract infection. Physical examination reveals multiple ecchymoses and petechiae; no lymphadenopathy or hepatosplenomegaly is noted. The next diagnostic step is

A 5-day-old full-term male presents with intense cyanosis, tachypnea, and tachycardia. Physical examination reveals cyanosis of the skin and mucous membranes; the lungs, heart, pulses, and general examination show no abnormalities. Arterial blood gas determination reveals a PaOâ‚‚ of 95 while the patient is breathing room air and an oxygen saturation of 40%. The most likely diagnosis is