Blood Test for Biological Age May Predict Dementia Risk

Lactate dehydrogenase, commonly known as LDH, is an enzyme found in nearly all body tissues. It plays a crucial role in converting sugar into energy that cells can use. When tissues are damaged or cells break down, LDH is released into the bloodstream, making it a useful marker for detecting tissue damage. A blood test measuring LDH levels can help healthcare providers identify and monitor various medical conditions affecting different organs, including the heart, liver, kidneys, lungs, muscles, and blood cells.

The LDH test is ordered for several reasons. It may be requested when a person shows symptoms suggesting tissue or cell damage, such as unexplained fatigue, weakness, shortness of breath, abdominal pain, or signs of anemia. Healthcare providers often use this test to help diagnose conditions like hemolytic anemia, where red blood cells are destroyed prematurely, or to detect tissue damage from heart attacks, liver disease, or muscle injury. The test is also valuable in monitoring certain cancers, particularly lymphomas and leukemias, as well as tracking the progression of diseases that affect multiple organs.

Elevated LDH levels indicate that tissue damage has occurred somewhere in the body, though the test itself does not specify the exact location or cause. High levels can result from numerous conditions including heart attack, stroke, liver diseases such as hepatitis or cirrhosis, severe muscle injury, muscular dystrophy, pancreatitis, kidney disease, infectious mononucleosis, meningitis, encephalitis, HIV, certain cancers, and hemolytic or megaloblastic anemia. Very strenuous exercise can also temporarily raise LDH levels. Because LDH is present in so many tissues, additional tests are usually needed to pinpoint the specific source of the elevation.

The LDH blood test requires a simple blood sample drawn from a vein, typically in the arm. No special preparation is usually needed, though patients should inform their healthcare provider about all medications and supplements they are taking, as some substances can affect test results. Normal LDH levels generally range from 140 to 280 units per liter for adults, though reference ranges may vary slightly between laboratories. Results should always be interpreted by a healthcare provider in the context of other test findings, symptoms, and medical history to determine the underlying cause of any abnormality and guide appropriate treatment decisions.