Labs
Assumptions
Defaults: AST 17 h, ALT 72 h, LDH 24 h; 10 steps of 12 hours. Whole hours.
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Estimated earlier values
Enter at least one enzyme.
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Calculator · Timing of liver injury
Work backward from today’s AST, ALT, and LDH to estimate what they were hours or days ago, using each enzyme’s half-life.
Defaults: AST 17 h, ALT 72 h, LDH 24 h; 10 steps of 12 hours. Whole hours.
Results update as you type. Nothing leaves your browser.
Enter at least one enzyme.
The chart and table fill in as you type.
Enzymes are cleared from the blood at a roughly constant fraction per hour, so each level halves every half-life. Going back in time reverses that: the value h hours earlier is today’s value × 2h / half-life.
AST clears fastest (about 17 hours), so it climbs fastest as you go back. ALT clears slowly (about 72 hours). The estimates assume clearance alone, with no ongoing injury, which is why they are most useful after a single, time-limited insult such as ischemia or a toxic ingestion.