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Lab Safety Alerts

Understanding critical value alerts and when to seek medical care

3 min readUpdated Sep 2, 2026

A result far enough outside its reference range is flagged critical, and a

critical result raises a safety alert.

What counts as critical

The bounds come from the reference range on the result: at or below half of

the lower bound is critically low, at or above one and a half times the

upper bound is critically high. A potassium range of 3.5–5.1 mmol/L, for

instance, makes 1.7 critically low and 7.7 critically high. There is no table

of fixed thresholds — every result is judged against its own range, so a result

with no range can never be critical.

Where an alert appears

  • Dashboard (web) — a banner headed "Critical … level" naming the marker and its value, with the line "Contact your healthcare provider straight away." You can mark it I’ve read this or Dismiss
  • Lab Results (web) — the panel's summary opens with how many values require immediate attention, and the result carries a "Critically low" or "Critically high" flag
  • Lab Summary (phone) — a Safety Alerts section on the home screen's lab summary
  • Medication alerts share the banner. Those come from your medication list and

    conditions rather than from a lab value, and are explained in

    Contraindication Warnings.

    What to do

  • Contact your doctor — or urgent care, if you cannot reach them
  • Do not treat it with food — a critical value is a clinical matter, not a dietary one
  • Keep the panel — your clinician can see the value, its range and the date on the clinician report
  • A result that is merely low or high is not an alert. It is shown with its flag,

    counted in the interpretation, and is the kind of thing the food

    recommendations are for.

    Limits

    An alert is worked out from the number on the report and nothing else. ClapDiet

    does not know your history, your symptoms, or whether the value is expected for

    you. Adding conditions to your profile changes the medication and dietary

    guidance you see; it does not move the critical bounds.

    When in doubt, treat the alert as real and ask a clinician.
    Related Articles:
  • Understanding Lab Interpretations
  • Contraindication Warnings
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