Understanding Lactate Dehydrogenase and Heart Attacks

Lactate dehydrogenase, or LDH for short, is an important enzyme. It helps change a substance called pyruvate into lactate while also converting NADH into NAD+. This process is especially important when the body is not getting enough oxygen, such as during a heart attack. Because of this, LDH is very useful for doctors when they need to diagnose heart problems.

What is LDH?

LDH comes in different forms, known as isoforms. The main types are LDH-1 through LDH-5, with LDH-1 being the most common in the heart. The way LDH works shows that it has a strong attraction to pyruvate and NADH. This means it can work well even when there’s not much oxygen available, which is important during heart issues.

How LDH Levels Help Diagnose Heart Attacks

When someone has chest pain or a heart attack, checking their LDH levels can give doctors important information. When the heart is damaged, cells release LDH into the blood. Here are some key points about its role in diagnosis:

1. When Does LDH Rise?

   • LDH levels increase about 1 to 2 days after heart damage.
   • They can go up to 3 to 5 times higher than normal, depending on how bad the heart attack is.
   • These levels can stay high for up to 2 weeks after the heart attack.

2. Understanding LDH Types for Diagnosis:

   • The ratio of LDH-1 to LDH-2 is important for diagnosing heart attacks. Normally, this ratio is about 0.8. If it goes above 1, it suggests that heart cells are damaged.
   • Research shows that using LDH patterns for diagnosis is accurate about 86% of the time.

3. How LDH Compares to Other Tests:

   • Today, specific proteins called troponins are the main tests used to diagnose heart attacks. However, LDH can still provide helpful information, especially if the troponin test is unclear.
   • LDH is particularly helpful for diagnosing heart attacks that happen later on when troponin levels might start to go back to normal.

Why LDH is Important in Research

Studies have shown that looking at LDH along with other tests can improve diagnosis:

• If both LDH and troponin I levels are high, the chance of diagnosing a heart attack correctly goes up.
• For every 100 U/L increase in LDH, the chances of having a heart attack go up by about 10%.

Conclusion

Lactate dehydrogenase plays a key role in helping doctors diagnose heart attacks. By understanding how LDH behaves and what its different forms mean, doctors can make better decisions when treating heart issues. Even though new tests are being developed, LDH remains an important tool for understanding heart damage and providing crucial information about a patient's condition.