Which LD isoenzyme is slightly increased in pulmonary conditions and pancreatitis?

Which LD isoenzyme is slightly increased in pulmonary conditions and pancreatitis?

• A. LD1
• B. LD2
• C. LD3
• D. LD4

Answer: (C)

Lactate dehydrogenase has five isoenzymes, each with a characteristic tissue distribution. LD-3 is most abundant in lung tissue, so when the lungs are affected, LD-3 is released into the serum and tends to rise slightly. Pancreatitis mainly involves the pancreas, where LD-4 and LD-5 are more commonly elevated, but some LD-3 can also appear due to broader tissue injury or systemic effects. Because LD-3 is the isoenzyme linked to lung tissue and can show at least a small increase in pulmonary conditions, it best fits the scenario described.

Lactate dehydrogenase has five isoenzymes, each with a characteristic tissue distribution. LD-3 is most abundant in lung tissue, so when the lungs are affected, LD-3 is released into the serum and tends to rise slightly. Pancreatitis mainly involves the pancreas, where LD-4 and LD-5 are more commonly elevated, but some LD-3 can also appear due to broader tissue injury or systemic effects. Because LD-3 is the isoenzyme linked to lung tissue and can show at least a small increase in pulmonary conditions, it best fits the scenario described.