Delta check (change from the last result)
Reports how far a result has moved from the last one on the same patient, three ways: the absolute difference, that difference as a percent of the previous result, and the rate per 24 hours of elapsed time.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Previous result
- 1.0
- Current result, in the same units
- 2.4
- Hours between the two results
- 12
- Absolute delta threshold, if the laboratory has one
- 0.5
Result: flagged on the absolute delta, which is a reason to look and not a specimen problem
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Absolute delta
- The current result minus the previous one.
- Percent delta
- That difference over the previous result. Undefined when the previous result was zero.
- Rate
- That difference per 24 hours. The same difference over six hours and over six days are not the same finding.
- The thresholds
- Local. There is no published universal set, and nothing here supplies one; with none entered, nothing is flagged.
- A flag
- A change, not an error. The check was invented to catch mislabeled specimens, and most of what it flags is real clinical change.
- A better threshold
- Where the biological variation of the analyte is known, the reference change value is the principled one.
What you enter
- Previous result
- Current result, in the same units
- Hours between the two results
- Absolute delta threshold, if the laboratory has one
- Percent delta threshold, if the laboratory has one
- Rate threshold per 24 hours, if the laboratory has one
How this is calculated
Ladenson JH. Patients as their own controls: use of the computer to identify "laboratory error". Clin Chem. 1975;21(11):1648-1653. Randell EW, Yenice S. Delta checks in the clinical laboratory. Crit Rev Clin Lab Sci. 2019;56(2):75-97. Read the sources: Ladenson 1975 ↗, Randell 2019 ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.