Understanding Lactate Levels for Student Nurses
Learn what lactate is, why levels may rise and how to connect a lactate result with circulation, infection, tissue perfusion and the patient's overall clinical condition.
What is lactate?
Lactate is produced during normal metabolism. Blood lactate can rise in several clinical situations, including circumstances involving impaired tissue perfusion or increased metabolic demand. Its meaning depends on the patient, the cause and the trend over time.
One number
A lactate measurement provides useful information but should never be interpreted separately from the patient.
Clinical context
Observations, circulation, consciousness, infection and other findings determine how concerning the result may be.
Direction matters
Repeat results can help the clinical team assess whether the patient's physiological disturbance is improving or worsening.
Why might lactate rise?
| Context | What may be happening | What to connect it with |
|---|---|---|
| Circulatory compromise | Tissue perfusion may be inadequate. | Blood pressure, pulse, perfusion, urine output and consciousness. |
| Severe infection | Significant physiological stress may be present. | Temperature, observations, infection signs and overall deterioration. |
| Hypoxia | Oxygen delivery to tissues may be impaired. | Respiratory assessment, oxygen saturation and the wider ABCDE picture. |
| Seizure | Intense muscular activity can temporarily increase lactate. | Recent events, neurological status and repeat clinical assessment. |
| Severe physiological stress | Metabolic demand may be increased. | The patient's underlying illness and overall physiological state. |
| Other causes | Medication, metabolic and organ-related factors may contribute. | History, medicines, blood results and clinical-team assessment. |
Think beyond the number
The useful question is not simply βIs the lactate raised?β It is βWhat is happening to this patient that might explain this result?β
What should you look for alongside an elevated lactate?
Perfusion
Look at pulse, blood pressure, peripheral perfusion and the overall cardiovascular pattern.
Urine output
Falling urine output may contribute to a wider picture of impaired organ perfusion or acute illness.
Consciousness
New confusion, agitation, drowsiness or reduced responsiveness requires prompt attention.
Respiratory rate
Tachypnoea may be an important early sign of physiological disturbance.
Look for context
Consider temperature, known infection, wounds, respiratory symptoms and other relevant findings.
Compare observations
A changing lactate becomes more meaningful when connected with improving or deteriorating observations.
Use ABCDE to assess the patient
Airway
Confirm airway patency and identify any immediate threat.
Breathing
Assess respiratory rate, effort, oxygen saturation and the patient's prescribed oxygen target where relevant.
Circulation
Assess pulse, blood pressure, peripheral perfusion, fluid balance and urine output.
Disability
Assess consciousness and identify new confusion or reduced responsiveness.
Exposure
Look for temperature change, infection, bleeding, fluid loss and other clinical clues.
Escalate
Significant deterioration or concerning lactate results require appropriate registered and medical review.
Why does the lactate trend matter?
A repeat lactate may be requested as part of ongoing clinical assessment. The direction of change can provide additional information when interpreted alongside the patient's response and observations.
May support improvement
A falling result may be reassuring when the patient's wider clinical condition is also improving.
Needs context
Persistent elevation may prompt further assessment depending on the underlying cause and clinical picture.
May increase concern
A rising result alongside deteriorating observations can indicate a worsening physiological problem.
Trend + patient = meaning
Never interpret the direction of lactate change without considering what is simultaneously happening to the patient.
When should a raised lactate increase your concern?
- A rising lactate alongside worsening observations.
- Hypotension or other evidence of circulatory compromise.
- Tachycardia with deteriorating peripheral perfusion.
- Reduced urine output.
- New confusion, drowsiness or reduced responsiveness.
- Increasing respiratory rate or respiratory distress.
- Suspected serious infection with physiological deterioration.
- Evidence of significant bleeding or fluid loss.
- A patient who simply looks substantially more unwell than earlier.
Putting lactate into context
Example
A patient being treated for an infection appears noticeably more unwell than earlier in the shift.
Their respiratory rate and pulse have increased, their blood pressure has fallen and their urine output has reduced.
They are now mildly confused and a blood gas shows an elevated lactate.
The important finding is not the lactate alone. It is the combined pattern of physiological deterioration, impaired circulation, altered consciousness and an abnormal laboratory result.
As a student nurse, continue an appropriate ABCDE assessment within your competence and promptly communicate and escalate your concerns.
Lactate interpretation mistakes to avoid
- Assuming every raised lactate means sepsis.
- Looking at the laboratory result without looking at the patient.
- Ignoring the direction of change on repeat results.
- Missing hypotension, poor perfusion or reduced urine output.
- Waiting for blood results before escalating obvious deterioration.
- Trying to diagnose the exact cause independently.
- Ignoring clinical concern because one observation appears normal.
Communicate the result with the clinical picture
Example escalation
βI'm concerned about Mrs Green. She looks more unwell than earlier. Her respiratory rate and pulse have increased, her blood pressure has fallen and her urine output is reduced. She is now mildly confused and her latest lactate is elevated.β
This communicates the patient's deterioration, circulation, neurological change and laboratory finding rather than simply reporting a number.
Recognise β assess β communicate β escalate
Notice the result
Understand that an elevated or changing lactate may provide an important clue to physiological disturbance.
Look at the patient
Connect lactate with ABCDE, circulation, consciousness, urine output and the wider clinical context.
Report the pattern
Communicate the lactate result together with what has changed clinically and whether the patient is deteriorating.
Build your acute-assessment skills
Continue learning how blood results, observations and bedside assessment fit together within the NurseNet Clinical Confidence pathway.
Explore Clinical Confidence β