Multiple clinical, laboratory, radiologic, and microbiological data are required for the diagnosis of sepsis and septic shock. Sepsis cannot be diagnosed on the basis of a single abnormality. However, the diagnosis is often made empirically at the bedside upon presentation or retrospectively when follow-up data are returned (eg, a positive blood culture result) or a response to antibiotics is evident.
A complete blood cell count is usually not specific. Leukocytosis with a left shift is also a nonspecific diagnostic finding and can be seen in noninfectious conditions. Leukopenia, anemia, and thrombocytopenia may be observed in sepsis.
Obtain blood cultures in all patients upon admission. Organism identification via culture in a patient who fulfills the definition of sepsis is highly supportive but unnecessary for a diagnosis of sepsis. The rationale behind its lack of inclusion in the diagnostic criteria for sepsis is that a culprit organism goes unidentified in as many as half of patients who present with sepsis, and a positive culture result is not required to make a decision regarding treatment with empirical antibiotics.
Laboratory and clinical features that may suggest an underlying etiology of sepsis are as follows:
Leukocytosis (white blood cell [WBC] count > 12,000 cells/µL) or leukopenia (WBC count < 4000 cells/µL)
Normal WBC count with > 10% immature forms (left shift with bandemia)
Hyperglycemia (plasma glucose level > 140 mg/dL [> 7.7 mmol/L]) in the absence of diabetes
Plasma C-reactive protein level more than two standard deviations above the reference value
Arterial hypoxemia (PaO2/FiO2 ratio < 300 mm Hg)
Acute oliguria (urine output < 0.5 mL/kg/hr for at least 2 hours despite adequate fluid resuscitation)
Creatinine increase > 0.5 mg/dL or 44.2 mmol/L
Coagulation abnormalities (international normalized ratio > 1.5 or partial thromboplastin time > 60 sec)
Thrombocytopenia (platelet count < 100,000 cells/µL)
Hyperbilirubinemia (plasma total bilirubin > 4 mg/dL [> 70 mmol/L])
Adrenal insufficiency (eg, hyponatremia, hyperkalemia) and euthyroid sick syndrome can also be found in sepsis. Hyperlactatemia (serum lactate level > 2 mmol/L) can result from organ hypoperfusion in the presence or absence of hypotension and indicates a poor prognosis. A serum lactate level ≥ 4 mmol/L (especially arterial lactate) indicates septic shock. Plasma procalcitonin level and presepsin level elevation are associated with bacterial infection and sepsis.
Read more about the workup of sepsis.
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Richard H. Sinert. Fast Five Quiz: Sepsis Key Aspects - Medscape - Jun 17, 2020.
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