Elevated lactate

at the bedside

is it real → venous is fine for lactate; a long tourniquet, a fist clenched, or a sample left standing raises it; doubt → repeat a free-flowing sample, run at once
then the patient → airway, breathing, circulation; full vitals; perfusion: mental state, capillary refill, skin, urine output
the number → normal < 2 mmol/L; 2–4 look for the cause; ≥ 4 → senior review now and a full perfusion check; fluids follow the assessment, not the number; compare with the last value
drug chart → metformin, salbutamol nebs, epinephrine, linezolid; a seizure in the last hours

escalate now if

hypotension or poor perfusion, at any lactate → hypotension, ICU
septic shock, or probable / definite sepsis → cultures, antibiotics within 1 h → fever; possible sepsis without shock → assess, cultures, monitor closely, antibiotics once infection is likely
lactate ≥ 4, or rising on repeat → senior and ICU now
pain out of proportion to the abdomen, or a cold pale limb → ischemia, surgery now
on metformin with AKI and acidosis → metformin, ICU and nephrology

hypoperfusion → sepsis, bleeding, dehydration, cardiogenic shock, PE
local ischemia → mesenteric ischemia, acute limb ischemia, compartment syndrome; the BP can be normal
no hypoperfusion → salbutamol or epinephrine, after a seizure, heavy work of breathing, liver failure
drugs and toxins → metformin (worse with AKI), linezolid, alcohols, cyanide
rare → thiamine deficiency (alcohol, malnutrition), malignancy

perfusion → capillary refill, mottling, cold peripheries, urine output, confusion
source → chest, urine, abdomen, lines, wounds, skin
abdomen and limbs → tenderness, distension, AF; pulses, a tense painful compartment
hidden bleeding → melena, a post-op site, an anticoagulant

gas → pH, HCO₃, anion gap, glucose, K⁺ → venous blood gas
bloods → CBC, RFT, LFT, coagulation; blood cultures if infection is possible
if indicated → CK (limb pain, long lie); troponin and ECG (chest pain); ketones (diabetes)
imaging → CT angiography if mesenteric or limb ischemia is suspected, decided with surgery

hypoperfusion or sepsis

balanced crystalloid 250–500 mL IV bolus, reassess perfusion, lungs and JVP before the next → hypotension
sepsis-induced hypoperfusion or septic shock → crystalloid 30 mL/kg IV over the first 3 h, individualized and reassessed after each bolus; lactate ≥ 4 alone is not a fluid order; still hypotensive → norepinephrine and ICU
bleeding → hemoglobin drop; massive → massive hemorrhage

suspected ischemia

general surgery or vascular now; nil by mouth, IV access, CT angiography per surgery

no hypoperfusion

salbutamol or epinephrine → perfusion normal: no fluid for the number; review neb frequency with the treating team
after a seizure → repeat in 1–2 h; still high → look again
alcohol or malnutrition → thiamine 200–300 mg IV promptly when indicated, preferably before or alongside glucose if feasible, but never delay emergency dextrose for hypoglycemia
metformin → stop it; lactate > 20, pH ≤ 7.0, shock, falling consciousness, or worse despite support → ICU and nephrology for dialysis

bicarbonate → not to correct the number; an ICU decision
recheck → lactate > 2 → repeat within 2–4 h; aim for a falling trend with better perfusion, not a normal number
hand over → value and trend, presumed cause, fluids and antibiotics given, next lactate due, escalation trigger

source	type
SSC 2026 · Sepsis and septic shock ↗︎	international guideline
SSC 2018 · Hour-1 bundle (remeasure lactate) ↗︎	international guideline
NEJM 2014 · Lactic acidosis ↗︎	review
EXTRIP 2015 · Metformin poisoning ↗︎	consensus recommendations

Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.

free the on-call checklist covers the whole shift on one printable page.

studying for the IM exam? the IM Rapid Review covers this in the same format. see the sample chapter.

updated Oct 2026file lab/lactate