Which LD isoenzyme is known as LD 3?

The correct answer is that LD isoenzyme LD 3 is associated with the lung. Lactate dehydrogenase (LD) is an enzyme that exists in various isoenzymes, each of which differs slightly in structure and function. These isoenzymes are categorized based on the tissues they predominantly originate from and are often used in clinical diagnostics to identify tissue damage or specific conditions.

LD 3 is primarily found in the lungs and lymphoid tissues, making it an important biomarker for lung-related pathologies. When lung tissue is damaged or diseased, levels of LD 3 in the bloodstream may rise, indicating potential health issues such as pneumonia or pulmonary infarction.

Each of the other isoenzymes corresponds to different tissues: LD 1 is predominantly found in the heart, LD 2 is found in the heart and red blood cells, LD 4 is associated with the liver, and LD 5 is primarily in the liver and skeletal muscles. This tissue specificity is crucial in analyzing patient serum samples for diagnosing various conditions, allowing healthcare providers to infer the likely location of tissue damage based on the isoenzyme patterns present.