- To determine the half-life of an analyte in the circulation enter two measured results
in the boxes above and the time in hours between the measurements.
- Move between the boxes and perform the calculation with the tab key.
- The result can be compared to the data below to assess whether the change in analyte
concentration is due to clearance alone, or whether other factors are involved.
- If several results are available during the fall in analyte concentration the half-life
calculated from each pair should be similar.
- Both results must be taken from the time when the analyte concentration is falling.
Falsely long half-livers can be seen if the first result is taken prior to the analyte
starting to fall or if the second result is taken after the fall in concentration is
- The data is not stored electronically. All transcriptions must be checked for errors.
Half-life Reference Data.
- AFP: 96-168 hours (4-7 days)
- ALP: 240 hours (10 days)
- ALT: Approx 50 hours
- AST: approx 14 hours
- CA 125: 144 hours (6 days)
- CK (skeletal): 15 - 18 hours
- CK-MB: approx 13 hours
- CRP: 19 hours
- GGT: 96 hours (4 days)
- Lacate: 4 hours (after siezures, physical activity)
- LDH: Between 10 (pure LD1) and 100 hours (pure LD5)
- Lipase: 7-13 hours
- Tri-iodothyronine: 36 hours
- Thyroxine: 169 hours (approx 1 week)
|(with thanks to M R Holland, Knowledge in Capsular Form)