Lactate is a substance produced naturally in the body, primarily as a byproduct of cellular energy production. Under normal circumstances, the body efficiently processes and removes lactate, maintaining healthy levels. However, when lactate accumulates to high levels, it can indicate an underlying health issue, especially in babies, signaling that the body’s cells may not be receiving enough oxygen or are struggling to use it properly. Understanding these reasons is important for addressing potential health concerns in infants.
Understanding Lactate and Its Role
Lactate, often referred to as lactic acid, forms when the body breaks down glucose for energy without sufficient oxygen. This process, known as anaerobic metabolism, occurs when oxygen supply is limited. While lactate is a normal part of metabolism and can even serve as an energy source for tissues like the brain, its accumulation beyond typical levels can signal a metabolic imbalance.
When lactate builds up faster than the liver and kidneys can clear it, it leads to a condition called hyperlactatemia. If severe enough to cause an acidic pH in the blood, it is termed lactic acidosis. This imbalance suggests that cells are either not getting enough oxygen or are unable to effectively use the oxygen they receive, leading to an inefficient energy production. Normal venous lactate levels in healthy children typically range from 0.5 to 2.2 mmol/L, with capillary blood levels for infants 0-2 months old ranging from 1.1–3.5 mmol/L.
Common Causes of High Lactate Levels
Several common conditions can lead to elevated lactate levels in babies, often stemming from issues with oxygen delivery or cellular energy use. A frequent cause is tissue hypoxia, meaning the body’s tissues are not receiving enough oxygen. Conditions like respiratory distress, where a baby struggles to breathe, can significantly reduce oxygen supply. Congenital heart defects that impair blood circulation or severe anemia, which reduces the oxygen-carrying capacity of blood, also lead to insufficient oxygen delivery, forcing cells into anaerobic metabolism and increasing lactate production.
Severe infections, such as sepsis, represent another common cause of elevated lactate in infants. Sepsis can cause widespread inflammation and damage to blood vessels, impairing oxygen delivery and utilization at the cellular level. This cellular dysfunction leads to lactate accumulation. Dehydration or different types of shock can also result in high lactate levels. These conditions cause reduced blood flow and inadequate perfusion of organs, decreasing oxygen delivery to tissues.
Certain medications can interfere with the body’s metabolic processes, leading to lactate buildup. For example, some antiretroviral drugs can affect mitochondrial function, disrupting normal energy production and causing lactic acidosis. Low blood sugar, known as hypoglycemia, can also contribute to elevated lactate. When glucose, the primary energy source, is scarce, the body may shift towards anaerobic metabolism to produce energy, increasing lactate levels.
Less Common and Inherited Causes
Beyond the more common causes, high lactate levels in babies can also point to less frequent but significant underlying conditions, particularly inherited disorders. Inborn errors of metabolism are a group of genetic conditions where the body lacks specific enzymes needed to process nutrients, leading to a buildup of harmful substances, including lactate. These disorders can impair the body’s ability to metabolize energy, often by affecting specific metabolic pathways or the mitochondrial respiratory chain.
Mitochondrial disorders are specific types of inborn errors of metabolism that directly affect the mitochondria, the “powerhouses” of the cells. When mitochondria do not function properly, cells cannot efficiently use oxygen to produce energy, forcing them to produce lactate. Organic acidemias, another category of inherited metabolic disorders, can also lead to elevated lactate as a secondary effect due to interference with metabolic pathways.
Severe liver disease can also contribute to elevated lactate levels. The liver plays a primary role in clearing lactate from the bloodstream by converting it back into glucose. When liver function is severely impaired, it cannot effectively remove lactate, leading to its accumulation. Impaired kidney function can also affect the body’s ability to excrete lactate and maintain proper acid-base balance, contributing to elevated levels.
When to Seek Medical Help
Parents should be aware of certain signs in their baby that warrant prompt medical attention, as they could be associated with elevated lactate levels or other serious health issues. These symptoms include unusual lethargy or excessive sleepiness, poor feeding or a decrease in appetite, and rapid or labored breathing. Other concerning signs might include unusual fussiness or irritability, as well as changes in skin appearance, such as paleness or a mottled look. Parents should seek medical advice immediately if they observe any combination of these symptoms in their baby, as early diagnosis and intervention can improve outcomes.