The isoenzymes LD-4 and LD-5 are elevated in

The isoenzymes LD-4 and LD-5 are elevated in

• A. Liver disease
• B. Pulmonary embolism
• C. Renal disease
• D. Myocardial infarction

Answer: (A)

LDH has five isoenzymes, and where they come from in the body helps tell where tissue injury is. LD-4 and LD-5 are most abundant in liver (and to some extent in skeletal muscle). When liver cells are damaged, these two isoenzymes are released into the blood, so their levels rise. That pattern is why liver disease best fits the scenario. In contrast, myocardial infarction tends to raise LD-1 and LD-2 (the heart/red blood cell–rich isoenzymes), not the LD-4 and LD-5 pair. Pulmonary conditions can affect LD levels but don’t specifically point to LD-4 and LD-5. Renal disease doesn’t selectively elevate these two isoenzymes.

LDH has five isoenzymes, and where they come from in the body helps tell where tissue injury is. LD-4 and LD-5 are most abundant in liver (and to some extent in skeletal muscle). When liver cells are damaged, these two isoenzymes are released into the blood, so their levels rise. That pattern is why liver disease best fits the scenario.

In contrast, myocardial infarction tends to raise LD-1 and LD-2 (the heart/red blood cell–rich isoenzymes), not the LD-4 and LD-5 pair. Pulmonary conditions can affect LD levels but don’t specifically point to LD-4 and LD-5. Renal disease doesn’t selectively elevate these two isoenzymes.