The erythrocyte sedimentation rate (ESR) is a common blood test measuring how quickly red blood cells, or erythrocytes, settle in a test tube, typically within one hour. It serves as a non-specific indicator of inflammation or disease activity within the body. A high ESR suggests inflammation but does not identify its precise cause or location.
The Mechanism Behind Elevated ESR
An elevated ESR occurs when inflammation changes blood proteins. During an inflammatory response, the liver produces increased acute phase proteins, such as fibrinogen. These proteins coat red blood cells, reducing their normal negative charge and allowing them to clump into stacks called rouleaux. These heavier, aggregated red blood cells settle more rapidly at the bottom of the test tube, resulting in a higher ESR reading.
Common Inflammatory and Autoimmune Causes
Many inflammatory and autoimmune disorders can lead to a high ESR. Conditions like rheumatoid arthritis involve the immune system attacking its own tissues, leading to chronic inflammation. Systemic lupus erythematosus (SLE) also causes widespread inflammation, contributing to elevated ESR. Other autoimmune conditions, such as giant cell arteritis and polymyalgia rheumatica, show high ESR due to inflammation of blood vessels and muscles. Inflammatory bowel diseases (Crohn’s disease, ulcerative colitis) involve chronic digestive tract inflammation, and this persistent inflammation sustains elevated ESR by continuously producing acute phase proteins.
Infectious Diseases
Infectious diseases trigger the body’s immune response, leading to inflammation and an elevated ESR. Pathogens like bacteria, viruses, or fungi activate the immune system, releasing inflammatory mediators and increasing acute phase proteins, which accelerate red blood cell sedimentation. Common bacterial infections such as pneumonia, urinary tract infections, and osteomyelitis (bone infection) frequently cause a high ESR. Severe systemic infections can result in markedly elevated ESR values, sometimes exceeding 100 mm/hr. Viral and fungal infections may also cause an increase, though the degree of elevation varies by type and severity.
Malignancies and Other Conditions
Certain cancers are associated with elevated ESR due to induced chronic inflammation or abnormal protein production. Lymphomas (cancers of the lymphatic system) and multiple myeloma (a plasma cell cancer) frequently cause significantly high ESR. These cancers can trigger a systemic inflammatory response or produce proteins that promote red blood cell aggregation. Metastatic cancers (cancer spread from their original site) can also increase ESR, often due to widespread inflammation or tissue damage. Beyond cancers, kidney disease can contribute to a high ESR, especially if chronic inflammation is present, and severe tissue damage from trauma or injury also prompts an inflammatory response, elevating the sedimentation rate.
Interpreting Your ESR Results
A high ESR is not a specific diagnostic test and cannot pinpoint a single disease. Instead, it serves as a general indicator of inflammation. Healthcare professionals interpret ESR results in conjunction with a person’s overall symptoms, medical history, and the findings from other diagnostic tests. An elevated ESR suggests further evaluation is needed to determine the underlying cause. If ESR results are high, a healthcare professional will conduct additional investigations for an accurate diagnosis. The ESR provides a valuable clue, guiding further diagnostic steps rather than offering a definitive answer.