Serum Creatinine Phosphokinase (CPK) Isoenzyme Analysis (Lactate Dehydrogenase Isoenzyme Type 3, LD-3)

Why This Test Is Done

Your doctor may order this test if you’ve experienced symptoms like chest pain, shortness of breath, or unusual fatigue, which could signal heart-related issues. It’s also used after heart procedures or injuries to monitor recovery. Sometimes, it’s included in broader cardiac tests to evaluate heart function.

What to Expect Before the Test

You’ll typically have a small blood sample drawn from a vein in your arm. No special preparation is needed, but inform your doctor about any medications or recent illnesses, as they may affect results.

What the Results Mean

Elevated levels of this isoenzyme can indicate recent heart damage, such as a heart attack or stress on the heart muscle. However, results alone aren’t diagnostic—they’re usually interpreted alongside other test results and your medical history.

Common Causes of Abnormal Results

High levels may be caused by heart attacks, heart muscle inflammation, or conditions that strain the heart, like severe exercise or certain medications. Low levels are less common but could occur with certain muscle disorders or liver disease.