Laboratory investigations and assessment of illness severity

General principles

Laboratory investigations are requested to answer specific questions: Is infection present? Is kidney function impaired? Is there a systemic inflammatory response?

Minimum workup

• CBC.
• Creatinine, urea, electrolytes.
• Urinalysis.
• Urine culture (before antibiotics).

In a systemic inflammatory response

• Lactate.
• Blood cultures.
• Markers of organ dysfunction (bilirubin, platelets, blood gases, coagulation profile).

Assessment of severity

• qSOFA, SIRS, and NEWS may be used to assess risk and changes in the patient's condition. qSOFA must not be used as the sole screening test, and a low score does not exclude sepsis.
• Trends in laboratory values (creatinine, white blood cell count, CRP, lactate) have prognostic significance.

Algorithm