From the Guidelines
Based on the laboratory findings, I recommend ordering a complete blood cell (CBC) count with differential leukocyte count and platelet count, measurement of serum levels of creatinine and blood urea nitrogen, and measurement of electrolytes, hepatic transaminase enzymes, and total bilirubin, as well as at least 2 sets of blood cultures, as suggested by the Infectious Diseases Society of America 1. The patient's elevated white blood cell count (14.9) with increased neutrophils (11.2) suggests an inflammatory or infectious process that should be investigated further. The most recent and highest quality study, published in 2011, recommends laboratory tests, including a CBC count with differential leukocyte count and platelet count, and measurement of serum levels of creatinine and blood urea nitrogen, and measurement of electrolytes, hepatic transaminase enzymes, and total bilirubin 1. Additionally, the study suggests that at least 2 sets of blood cultures should be collected, with a set collected simultaneously from each lumen of an existing central venous catheter (CVC), if present, and from a peripheral vein site 1. Other laboratory tests, such as a urinalysis and urine culture, may also be helpful to rule out urinary tract infection as a source of the elevated white blood cells. The patient's low potassium level (2.9 mEq/L) and mildly elevated glucose level (116 mg/dL) should also be addressed, but the most urgent concern is to investigate the cause of the elevated white blood cell count. Key laboratory tests to order include:
- CBC count with differential leukocyte count and platelet count
- Measurement of serum levels of creatinine and blood urea nitrogen
- Measurement of electrolytes, hepatic transaminase enzymes, and total bilirubin
- At least 2 sets of blood cultures
- Urinalysis and urine culture (if clinically indicated) It is essential to note that the patient's clinical presentation and medical history should guide the selection of laboratory tests and the interpretation of results.
From the Research
Laboratory Test Interpretation
The patient's laboratory results show:
- WBC count: 14.9
- RBC count: 5.46
- Segmented neutrophil count: 11.2
- Monocyte count: 1.7
- Immature granulocyte count: 0.18
- Glucose level: 116
- Sodium level: 134
- Potassium level: 2.9
- Chloride level: 94
Potential Diagnoses and Further Testing
Based on the elevated WBC count and segmented neutrophil count, a bacterial infection may be suspected 2. To further investigate this possibility, the following tests could be ordered:
- Blood cultures to identify potential pathogens 3, 4, 5
- Imaging studies, such as SPECT/CT, to localize the source of infection 6
- Additional laboratory tests, such as electrolyte panels and liver function tests, to assess the patient's overall condition
Considerations for Test Ordering
When ordering laboratory tests, it is essential to consider the patient's clinical presentation and medical history. The results of these tests should be interpreted in conjunction with the patient's symptoms and physical examination findings. Effective communication between healthcare providers, laboratory personnel, and patients is crucial for accurate diagnosis and treatment 4, 5.