Hematology 103
duction. Treat with prophylactic penicillin until at least 10 years of age, beginning as soon as the
diagnosis is made. Proper vaccination includes the pneumococcal and H. influenzae vaccines
(given to all children anyway). Other strategies include folate supplementation, early treatment
of infections, and proper hydration.
A sickle cell crisis involves severe pain in various sites due to red blood cell sickling. Treat
with oxygen, lots of intravenous fluids, and analgesics (do not be afraid to use narcotics). Con-
sider transfusions if symptoms and/or findings are severe.
25. What findings help you in the setting of acute blood loss as a cause of anemia?
The important point is that immediately after blood loss the hemoglobin may be normal; it
takes at least 3-4 hours, often more, for reequilibration. Look for obvious bleeding, pale, cold
skin, tachycardia, and hypotension (signs of hypovolemic shock). Transfuse if indicated, even
with a normal hemoglobin in the acute setting. Consider internal hemorrhage in the setting of
trauma and abdominal aortic aneurysm in patients with a pulsatile abdominal mass.
26. What are the commonly tested causes of autoimmune hemolytic anemia?
• Lupus erythematosus (or medications that cause lupus-like syndromes, such as pro-
cainamide, hydralazine, and isoniazid) and other autoimmune disorders
• Drugs (the classic example is methyldopa, but penicillins, cephalosporins, sulfa drugs, and
quinidine also have been implicated)
• Leukemia or lymphoma
• Infection (the classic examples are mycoplasmosis, Epstein-Barr virus, and syphilis)
27. What lab test is often positive in patients with autoimmune anemia?
The Coombs test is positive in most autoimmune anemias. You also may see spherocytes on
peripheral smear because of incomplete macrophage destruction (extravascular hemolysis) of red
blood cells.
28. What clues point to lead poisoning as a cause of anemia?
Lead poisoning causes a hypochromic, microcytic anemia, almost always in a child. With
acute lead poisoning, look for vomiting, ataxia, colicky abdominal pain, irritability (aggressive,
behavioral regression), and encephalopathy, cerebral edema, or seizures. Usually, however, poi-
soning is chronic and low-level with minimal nonspecific symptoms. Watch for basophilic stip-
pling on peripheral smear, elevated free erythrocyte protoporphyrin or lead level, and consider
risk factors for lead exposure (a child who eats paint chips or lives in an old, run-down building).
29. True or false: Children with risk factors should be screened for lead poisoning.
True. Screening all asymptomatic children with a serum lead level at 1 and 2 years old regard-
less of risk is becoming controversial. In children with risk factors, screening is very important
because chronic low-level exposure may lead to permanent neurologic sequelae. Screening should
start at 6 months in children with risk factors, such as pica (especially paint chips and dust in old
buildings that may have lead paint), residence in an old or neglected building, and/or residence
near or family members who work at a lead-smelting or battery-recycling plant. Screen and meas-
ure symptomatic exposure with serum lead levels (normal value: < 10 ug/dl).
30. How is lead poisoning treated?
Treat initially with decreased exposure (best strategy) as well as lead chelation therapy, if
needed. Use succimer in children and dimercaprol in adults; in severe cases, use dimercaprol plus
ethylenediamine tetraacetic acid (EDTA) for children or adults.
31. How can sideroblastic anemia be recognized on the Step 2 exam? Should the presence
of sideroblastic anemia raise concern about other conditions?
The typical description is a microcytic, hypochromic anemia with increased or normal iron, fer-
ritin, and total iron-binding capacity (transferrin). This description should immediately steer you
