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  • imageThe most common drug-induced hematologic disorders are aplastic anemia, agranulocytosis, megaloblastic anemia, hemolytic anemia, and thrombocytopenia.

  • imageDrug-induced hematologic disorders are rare adverse effects associated with drug therapy.

  • imageThe incidence of rare adverse drug reactions (ADRs) is usually established by postmarketing surveillance and reporting.

  • imageRe-challenging a patient with an agent suspected of inducing a blood disorder is not generally recommended.

  • imageDrug-induced hematologic disorders can occur by two mechanisms: direct drug or metabolite toxicity or an immune reaction.

  • imageThe primary treatment of drug-induced hematologic disorders is the removal of the drug in question and symptomatic support of the patient.


Preclass Engaged Learning Activity

Watch the video entitled “Part 1: Anemia: Pathophysiology and Diagnostic Approach” in AccessMedicine by Scott Stern, MD. This can be found by clicking on Multimedia, Lectures, Diagnostic Reasoning, then Anemia. This 21-minute video provides an overview of the foundational knowledge of anemia, the approach to evaluate a patient with anemia, common causes of anemias, and differential diagnosis for different types of anemias. This video increases student understanding regarding the COLLECT and ASSESS steps in the patient care process.


image Hematologic disorders have long been a potential risk of modern pharmacotherapy. Granulocytopenia (agranulocytosis) was reported in association with one of medicine’s early therapeutic agents, sulfanilamide, in 1938.1 Some agents cause predictable hematologic disease (eg, antineoplastics), but others induce idiosyncratic reactions not directly related to the drugs’ pharmacology. The most common drug-induced hematologic disorders are aplastic anemia, agranulocytosis, megaloblastic anemia, hemolytic anemia, and thrombocytopenia.

image The incidence of idiosyncratic drug-induced hematologic disorders varies depending on the condition and the associated drug. Few epidemiologic studies have evaluated the actual incidence of these adverse reactions, but these reactions appear to be rare. Women are generally more susceptible than men to the hematologic effects of drugs. The incidence varies based on geography, which suggests that genetic differences may be important determinants of susceptibility. Drug-induced thrombocytopenia is the most common drug-induced hematologic disorder, with reports suggesting that between 0.1% and 5% of patients who receive heparin develop heparin-induced thrombocytopenia (HIT).2,3 The Berlin Case-Control Surveillance Study was conducted from 2000 to 2009 to assess the incidence and risks of drug-induced hematologic disorders and found that almost 30% of all cases of blood dyscrasias were “possibly” attributable to drug therapy.4

Although drug-induced hematologic disorders are less common than other types of adverse reactions, they are associated with significant morbidity and mortality. Aplastic anemia is the leading cause of death followed by thrombocytopenia, agranulocytosis, and hemolytic anemia.5 Similar to most other adverse drug reactions (ADRs), drug-induced hematologic disorders are more common in elderly adults than in the young; the risk of death also appears to be greater with increasing age.

image The MedWatch program supported by the Food and Drug Administration6 is the most common avenue ...

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