diagnostic biomarkers in sepsis in a secondary care setting

Overview

• diagnostic biomarkers in secondary care settings assist in evaluating sepsis severity, guiding rapid antimicrobial decisions, monitoring resuscitation efficacy, and supporting antimicrobial stewardship (1)
• guidance in NICE NG253 emphasizes routine point-of-care lactate measurement and formally introduces procalcitonin (PCT) testing alongside standard inflammatory panels in hospital settings (1)

Venous Blood Lactate

• obtain a venous blood gas (VBG) with lactate immediately upon arrival in secondary care for all adults presenting with suspected moderate-to-high risk sepsis (1)
• initial lactate > 2 mmol/L indicates systemic tissue hypoperfusion and necessitates immediate fluid resuscitation (250 ml isotonic crystalloid boluses) (1)
• serial lactate measurements every 30–60 minutes serve as an objective marker of resuscitation efficacy and restoration of organ perfusion (1)

Procalcitonin (PCT)

• consider procalcitonin (PCT) testing alongside routine venous bloods (FBC, CRP, U&Es, LFTs) in adults with suspected moderate- or high-risk sepsis in secondary care (1)
• PCT rises rapidly (within 2–4 hours) in response to systemic bacterial infections, providing significantly higher specificity for bacterial infection than C-reactive protein (CRP) (1)
• utility: supports clinical decision-making regarding initiation, continuation, or early de-escalation of empiric broad-spectrum antibiotics, particularly in moderate-risk patients where antibiotics may be deferred up to 3 hours for diagnostic workup (1)
• operational rule: do not delay first-dose empiric antibiotics while awaiting PCT or blood culture results in high-risk patients (1)

Standard Laboratory Investigation Panel secondary care clinicians should order the following core diagnostic panel during initial acute evaluation (1):

• full blood count (FBC): evaluates leukocytosis, leukopenia, or severe neutropenia (neutrophil count <= 0.5 x 10^9/L)
• C-reactive protein (CRP): baseline inflammatory marker to monitor clinical trajectory over 24–48 hours
• blood cultures: two sets of peripheral blood cultures (plus central line cultures if an indwelling device is present) obtained prior to antibiotic administration where feasible
• organ function panels: U&Es, LFTs (including albumin), and clotting screen to identify acute end-organ dysfunction

References

1. National Institute for Health and Care Excellence (NICE). Suspected sepsis in people aged 16 or over: recognition, assessment and early management (NG253). Published Nov 2025, updated Sep 2026.