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<< Evidence-Based Management Of Sickle Cell Disease In The Emergency Department

Diagnostic Studies

In all but the simplest cases, laboratory evaluation for ED patients with SCD should include CBC, liver function studies, and reticulocyte count. In patients with worsened scleral icterus, back pain, fever, or signs that suggest hemolysis, additional tests would include alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and bilirubin fractionation. Blood typing and screening is necessary if hemoglobin has dropped more than 1 mg/dL below baseline or if there is concern that the patient may need a transfusion.

Can Laboratory Studies Be Used To Objectively Identify Vaso-Occlusive Crisis?
Laboratory tests are ordered to determine severity of disease and to compare clinical markers of disease with baseline values. Laboratory tests do not assist the clinician in determining whether or not the patient
is having VOC (ie, they cannot help determine whether or not a patient is being untruthful about his pain).

Several studies have explored the patterns of various laboratory markers during VOC, and although there are promising experimental assays, there are no commercially available laboratory tests that can objectively identify VOC. Two small observational cohort studies found no relationship between the presence of VOC and hemoglobin level, white blood cell (WBC) count, reticulocyte count, or change in hemoglobin from baseline.37,38 Larger prospective interventional clinical trials have noted hemoglobin concentrations of 8-10 mg/dL during crisis, which are not significantly different from baseline.34,35,39 Furthermore, there is evidence that reductions in hemoglobin are actually associated with decreased VOC. A before-and-after study of 7 patients found that regular phlebotomy significantly reduced frequency of VOC.40 The presence or absence of sickled RBCs is also unreliable as an objective measure of crisis. Although there have been no formally designed observational studies to test this, it is well known that sickled RBCs will be present in patients with SCD regardless of whether they are in crisis.41,42

Experimental assays for objective identification of VOC have included markers of inflammation such as high-sensitivity c-reactive protein (hs-CRP) and urinary leukotriene E4 (LTE4). In one prospective observational cohort, elevations in hs-CRP were significantly associated with the presence of VOC.43 Standard institutional CRP assays are unreliable because elevations occur days after the onset of crisis. The LTE4 has also shown correlation with presence of VOC in a small prospective cohort,37 but this test is not readily available.

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Last Modified: 07/23/2017
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