C-reactive protein, known as CRP, is a protein produced by the liver. Its level in the bloodstream rises in response to inflammation. It indicates inflammatory processes, signaling the body’s reaction to injury, infection, or other conditions. CRP is a general marker, indicating inflammation without revealing its specific cause or location.
Understanding CRP Test Results in Children
Interpreting CRP test results in children involves understanding specific numerical ranges, measured in milligrams per liter (mg/L). Normal CRP levels in children are typically very low, often below 3 mg/L, and sometimes even less than 1 mg/L, indicating no significant inflammation. For newborns, a normal range is often between 0 and 5 mg/L, while for children 4 weeks and older, it can range from 0 to 10 mg/L.
Mild to moderate CRP elevation in children generally falls within 3 to 10 mg/L, or slightly higher, indicating some inflammation. Levels between 10 and 50 mg/L often suggest mild inflammation, possibly from a minor viral infection. Significantly high CRP levels rise above 50 mg/L, sometimes exceeding 100 mg/L, often pointing towards substantial inflammation associated with bacterial infections. Laboratory reference ranges can differ slightly, so results are always interpreted within the specific lab’s guidelines.
Common Causes of Elevated CRP in Children
Elevated CRP levels in children can stem from various conditions that trigger inflammation. Infections are a frequent cause, with bacterial infections typically leading to higher CRP levels than viral infections. Common bacterial illnesses like strep throat, pneumonia, or urinary tract infections often cause noticeable CRP increases.
Viral infections generally cause milder CRP elevations, though values can still reach 20-40 mg/L. Some viral infections, like adenovirus or influenza, can even push CRP levels above 100 mg/L. Beyond infections, autoimmune and inflammatory conditions also elevate CRP.
Conditions like juvenile idiopathic arthritis (JIA), which causes joint inflammation, or inflammatory bowel disease (IBD), affecting the intestines, can lead to chronically elevated CRP. Physical injury, trauma, burns, or surgical procedures can also cause a temporary CRP rise as the body initiates healing.
When High CRP Levels Indicate a Serious Condition
When CRP levels in a child reach very high concentrations, often exceeding 100 mg/L, it can indicate a serious underlying condition requiring prompt medical attention. Levels between 150 and 350 mg/L are often observed with invasive acute bacterial infections. Such pronounced elevations strongly indicate a significant, often systemic, bacterial infection rather than a localized or mild inflammatory process.
Extremely elevated CRP levels, particularly at or above 300 mg/L, have been associated with severe infections, autoimmune diseases, or certain cancers. These high levels can signal life-threatening conditions such as sepsis, a severe bloodstream infection affecting multiple organs. Other serious conditions linked to very high CRP include osteomyelitis (a bone infection) or severe pneumonia. Studies indicate that extremely elevated CRP levels in hospitalized children correlate with unfavorable outcomes, including increased mortality, particularly in those with underlying conditions like cancer.
The Role of CRP in Medical Diagnosis
A CRP test result is one piece of information within a broader medical evaluation and is not a standalone diagnostic tool. A healthcare provider combines the CRP level with a thorough physical examination, a detailed review of symptoms, and medical history.
Other diagnostic tests are routinely performed alongside CRP measurements to understand the child’s condition. These may include a complete blood count (CBC) or blood cultures to identify specific bacterial infections. Imaging scans, such as X-rays or ultrasounds, might also pinpoint the source of inflammation or infection.
CRP levels are also valuable for monitoring treatment effectiveness. A decrease in CRP levels over time can indicate that the chosen therapy, such as antibiotics, is working and inflammation is resolving. Conversely, persistent or rising CRP levels might signal that treatment needs adjustment or further investigation is necessary.