Applied Evidence

Thrombocytopenia and neutropenia: A structured approach to evaluation

J Fam Pract. 2018 July;67(7):E1-E8

From The Journal of Family Practice | 2018;67(7):E1-E8.

References

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Is immune thrombocytopenia to blame?

Immune thrombocytopenia (ITP) is an autoimmune disorder resulting in the destruction of normal platelets and may be primary or secondary to processes described previously (HIT, H pylori infection, etc). Consider ITP if, after a thorough work-up, a cause of isolated thrombocytopenia is not identified.¹⁶ Treatment for ITP is outlined in TABLE 4.¹⁶ FIGURE 1 is an algorithm for the complete evaluation of thrombocytopenia in adults.

Treatment: Platelet transfusions

In general, patients who are not actively bleeding are considered stable and do not require platelet transfusions to minimize their risk of bleeding or prevent bleeding during a planned procedure unless their platelet count falls below the levels specified in TABLE 5.¹⁷ For patients who are actively bleeding, a more aggressive approach may be required. Locally-derived transfusion protocols typically guide transfusions for the actively hemorrhaging patient. The American Association of Blood Banks has put forth evidence-based guidelines for platelet transfusions when a patient is given a diagnosis of thrombocytopenia (see TABLE 5).¹⁷ Single-donor platelets have a shelf life of 3 to 5 days, and one unit will raise platelets 30,000 to 50,000/mcL.

Neutropenia: Prevalence varies by ethnicity

An absolute neutrophil count (ANC) of <1500 cells/mcL traditionally defines neutropenia, with an ANC of 1000 to 1500 cells/mcL constituting mild neutropenia; 500 to 999 cells/mcL, moderate; and <500 cells/mcL, severe.¹⁸ Similar to the evaluation of thrombocytopenia, it is important to repeat the CBC prior to initiating a work-up in order to confirm that the neutropenia is not a laboratory error. Additionally, patients with signs or symptoms of infection should be worked up expeditiously.

Heparin-induced thrombocytopenia occurs in <1% of patients in intensive care units and typically is manifested by a ≥50% drop in platelet count within 5 to 14 days of introducing heparin.

The prevalence of neutropenia varies by ethnicity. According to the National Health and Nutrition Examination Survey 1999 to 2004, the prevalence was 4.5%, 0.79%, and 0.38% in black, white, and Mexican-American participants, respectively.¹⁹ FIGURE 2 outlines the outpatient work-up of adult patients with neutropenia not related to chemotherapy.

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