Sepsis laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Parth Vikram Singh, MBBS [3]

Synonyms and keywords: sepsis syndrome; septic shock; septicemia

Overview

The international guideline committee for diagnosis of septic shock recommends obtaining appropriate cultures that may include at least two blood cultures, urine, cerebrospinal fluid, wounds, respiratory secretions, or other body fluid cultures before antimicrobial therapy is initiated. If such cultures do not cause significant delay in antibiotic administration, then other tests that may be done include blood gases, kidney function tests, platelet count, white blood cell count, blood differential, fibrin degradation products, and peripheral smear.^[1]^[2]

2016 Surviving Sepsis Campaign International Guidelines for Diagnosis of Severe Sepsis and Septic Shock (DO NOT EDIT)^[3]

“

1. The guideline committee recommends obtaining appropriate cultures before antimicrobial therapy is initiated if such cultures do not cause significant delay in antibiotic administration. To optimize identification of causative organisms, the committee recommends at least two blood cultures be obtained prior to antibiotics with at least one drawn percutaneously and one drawn through each vascular access device, unless the device was recently (less than 48 hours) inserted. Cultures of other sites (preferably quantitative where appropriate) such as urine, cerebrospinal fluid, wounds, respiratory secretions, or other body fluids that may be the source of infection should also be obtained before antibiotic therapy if not associated with significant delay in antibiotic administration. (Grade 1C)

2. The guideline committee recommends that imaging studies be performed promptly in attempts to confirm a potential source of infection. Sampling of potential sources of infection should occur as they are identified; however, some patients may be too unstable to warrant certain invasive procedures or transport outside of the ICU. Bedside studies, such as ultrasound, are useful in these circumstances. (Grade 1C)

”

Laboratory Findings

The laboratory findings of sepsis include:^[1]^[2]

Complete blood count

WBC count is elevated
Fever without localizing signs of infection and a WBC count higher than 15,000/µL is suggestive of bacterial infection
WBC counts higher than 50,000/µL is associated with poor outcome.
Platelets number may be elevated
The monocyte distribution width may help diagnose sepsis^[4].

Coagulation studies

Sepsis can activate complement system and initiate disseminated intravascular coagulation. In such cases, the following findings may be seen:

The prothrombin time and the aPTT are elevated
Fibrinogen levels are decreased
Fibrin split products are increased

Complete metabolic profile

Electrolytes
- Sodium and chloride levels are abnormal in severe dehydration.
- Decreased bicarbonate can result in acidosis
Hyperglycemia is associated with higher mortality.
Serum lactate is an indicator of tissue perfusion. Lactate levels higher than 2.5 mmol/L are associated with an increase in mortality.
Increased BUN and creatinine levels can point to severe dehydration or renal failure.
Liver function tests (LFTs) and levels of bilirubin, ALP, and lipase are important in evaluating multiorgan dysfunction or a potential causative source (eg, biliary disease, pancreatitis, or hepatitis)

Microbiological studies

Traditional culture-based methods remain central to sepsis diagnosis; however, improved detection using molecular tools (e.g., plasma metagenomics) is increasingly enhancing pathogen identification rates. In addition, transcriptome- and proteome-based diagnostic tools have been approved, though their clinical impact is still untested.^[5]

Type of Test	Findings
Blood culture	Sample must be collected prior to initiating antibiotic therapy The Surviving Sepsis Campaign recommends obtaining at least 2 blood cultures before antibiotics are administered Susceptibility testing for organisms that have a high risk for resistance (eg, Pseudomonas, Proteus, Acinetobacter, Staphylococcus aureus, and predominant [moderate to heavy growth] Enterobacteriaceae) should be performed Based on the result appropriate antibiotics should be started, delay in treatment is associated with poor outcomes
Urinalysis and urine culture	Indicated for every patient with sepsis Urinary tract infection is a common source of sepsis especially in elderly
Gram stain of specimens	Immediately available test 1 mL of fluid or tissue is needed Cerebrospinal fluid [CSF], wound tissue, respiratory secretions are some of the fluids employed for staining. Sputum sample in patients with a productive cough Any abscess should be drained promptly and purulent material sent for analysis

References

↑ ^1.0 ^1.1 Darmon M, Ostermann M, Cerda J, Dimopoulos MA, Forni L, Hoste E, Legrand M, Lerolle N, Rondeau E, Schneider A, Souweine B, Schetz M (2017). “Diagnostic work-up and specific causes of acute kidney injury”. Intensive Care Med. doi:10.1007/s00134-017-4799-8. PMID 28444409.
↑ ^2.0 ^2.1 Karnatovskaia LV, Festic E (2012). “Sepsis: a review for the neurohospitalist”. Neurohospitalist. 2 (4): 144–53. doi:10.1177/1941874412453338. PMC 3726110. PMID 23983879.
↑ Dellinger RP, Levy MM, Carlet JM, Bion J, Parker MM, Jaeschke R, Reinhart K, Angus DC, Brun-Buisson C, Beale R, Calandra T, Dhainaut JF, Gerlach H, Harvey M, Marini JJ, Marshall J, Ranieri M, Ramsay G, Sevransky J, Thompson BT, Townsend S, Vender JS, Zimmerman JL, Vincent JL. “Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008”. Critical Care Medicine. 36 (1): 296–327. doi:10.1097/01.CCM.0000298158.12101.41. PMID 18158437. Retrieved 2012-09-16.
↑ Huang YH, Chen CJ, Shao SC, Li CH, Hsiao CH, Niu KY; et al. (2023). “Comparison of the Diagnostic Accuracies of Monocyte Distribution Width, Procalcitonin, and C-Reactive Protein for Sepsis: A Systematic Review and Meta-Analysis”. Crit Care Med. doi:10.1097/CCM.0000000000005820. PMID 36877030 Check |pmid= value (help).
↑ Meyer NJ, Prescott HC (December 2024). “Sepsis and Septic Shock”. N Engl J Med. 391 (22): 2133–2146. doi:10.1056/NEJMra2403213. PMID 39774315 Check |pmid= value (help).

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[pmid28444409-1] 1.0 ^1.1 Darmon M, Ostermann M, Cerda J, Dimopoulos MA, Forni L, Hoste E, Legrand M, Lerolle N, Rondeau E, Schneider A, Souweine B, Schetz M (2017). “Diagnostic work-up and specific causes of acute kidney injury”. Intensive Care Med. doi:10.1007/s00134-017-4799-8. PMID 28444409.

[pmid23983879-2] 2.0 ^2.1 Karnatovskaia LV, Festic E (2012). “Sepsis: a review for the neurohospitalist”. Neurohospitalist. 2 (4): 144–53. doi:10.1177/1941874412453338. PMC 3726110. PMID 23983879.

[pmid18158437-3] Dellinger RP, Levy MM, Carlet JM, Bion J, Parker MM, Jaeschke R, Reinhart K, Angus DC, Brun-Buisson C, Beale R, Calandra T, Dhainaut JF, Gerlach H, Harvey M, Marini JJ, Marshall J, Ranieri M, Ramsay G, Sevransky J, Thompson BT, Townsend S, Vender JS, Zimmerman JL, Vincent JL. “Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008”. Critical Care Medicine. 36 (1): 296–327. doi:10.1097/01.CCM.0000298158.12101.41. PMID 18158437. Retrieved 2012-09-16.

[pmid36877030-4] Huang YH, Chen CJ, Shao SC, Li CH, Hsiao CH, Niu KY; et al. (2023). “Comparison of the Diagnostic Accuracies of Monocyte Distribution Width, Procalcitonin, and C-Reactive Protein for Sepsis: A Systematic Review and Meta-Analysis”. Crit Care Med. doi:10.1097/CCM.0000000000005820. PMID 36877030 Check |pmid= value (help).

[pmid39774315-5] Meyer NJ, Prescott HC (December 2024). “Sepsis and Septic Shock”. N Engl J Med. 391 (22): 2133–2146. doi:10.1056/NEJMra2403213. PMID 39774315 Check |pmid= value (help).

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