Lactate dehydrogenase (LDH) is an enzyme found in nearly all body tissues, playing a part in cellular energy production. It helps convert sugar into energy for cells. When cells are damaged due to injury or disease, they can release LDH into the bloodstream, leading to elevated levels. A high LDH level in a child can be unsettling for parents, but it serves as a general indicator that warrants further medical attention rather than a specific diagnosis.
Understanding Lactate Dehydrogenase
LDH is an enzyme present in various tissues throughout the body, including muscles, red blood cells, liver, kidneys, and heart. Its primary function involves the reversible conversion of lactate to pyruvate, a process central to generating cellular energy. While a small amount of LDH is normally present in the bloodstream due to natural cell turnover, elevated levels typically signal cell damage or disease. When cells sustain injury, their contents, including LDH, are released into the bloodstream, providing a measurable marker of tissue damage.
Why LDH Levels May Be High in Children
Elevated LDH levels in children can stem from a variety of causes, ranging from common and often temporary conditions to more serious underlying health issues.
Common Causes
Vigorous physical activity, for instance, can temporarily increase LDH levels due to muscle exertion. Infections, whether viral or bacterial, are a frequent cause, as the body’s immune response can lead to cell breakdown and inflammation. Conditions such as mononucleosis, meningitis, or encephalitis are examples of infections that can result in higher LDH readings. Tissue damage from injuries like bone fractures or muscle trauma can also lead to a rise in LDH levels.
More Serious Conditions
Certain types of anemia, particularly hemolytic anemia where red blood cells are destroyed prematurely, cause LDH to be released into the blood. Liver diseases, such as hepatitis, and kidney diseases can similarly result in elevated LDH due to damage to these organs. Muscle disorders, like muscular dystrophy, are also associated with increased LDH levels as muscle cells break down. In some instances, a high LDH level may be linked to certain cancers, including lymphomas, leukemias, or testicular cancer, where it can reflect increased cell turnover or tumor burden. Pancreatitis can also cause elevated LDH.
Interpreting High LDH Results and Next Steps
A high LDH level is a non-specific indicator, meaning it points to the possibility of tissue damage or disease but does not identify the specific cause or location. Healthcare providers use this information in conjunction with a child’s overall symptoms, medical history, and other diagnostic tests to determine the underlying reason for the elevation. For instance, if a child has symptoms of liver issues, liver function tests might be ordered alongside the LDH test.
The diagnostic process often involves:
Additional blood tests, such as a complete blood count to check for anemia, or specific enzyme tests like alanine aminotransferase (ALT) for liver health.
Imaging studies, including ultrasound or MRI, to visualize internal organs and identify any abnormalities.
An LDH isoenzymes test, performed to pinpoint the specific type of LDH that is elevated, which can help narrow down the affected tissue or organ. For example, LDH-5 is primarily found in the liver and skeletal muscles.
A pediatrician’s thorough assessment is always necessary to accurately interpret the results and guide subsequent steps.
Important Considerations for Parents
Upon learning of a high LDH level in their child, parents should avoid self-diagnosing and instead rely on the guidance of their child’s healthcare provider. Many causes of elevated LDH are treatable or may resolve without specific intervention.
Normal LDH ranges in children are typically higher than in adults and can vary with age; for instance, newborns may have levels between 135-750 U/L, while children aged 2-12 years might have ranges of 110-295 U/L. It is important to remember that only a medical professional can interpret the significance of a child’s specific LDH result within their individual clinical context. Parents should maintain open communication with their doctor and adhere to any recommended follow-up care to ensure their child receives appropriate management.