Blood Test

What it is: An ESR (erythrocyte sedimentation rate) test, or "sed rate," measures how quickly red blood cells settle to the bottom of a test tube over one hour as a general marker of inflammation.

Why it's ordered: Ordered to help detect or monitor inflammatory conditions such as rheumatoid arthritis, other autoimmune diseases, or infections, often alongside CRP.

What it detects: Inflammation increases certain blood proteins that cause red blood cells to clump and settle faster. ESR doesn't identify where or why inflammation is occurring — it's a nonspecific signal used to screen for or track inflammatory activity over time.

Collection & prep: A standard blood draw from a vein in the arm. No special preparation is required.

Results:

• High – suggests inflammation somewhere in the body; can also rise with age, infection, or other non-inflammatory conditions
• Normal – roughly 0–20 mm/hr in men and 0–30 mm/hr in women, varying by age and lab

Possible complications: ESR can't confirm or rule out a specific condition on its own; it's most useful for tracking inflammation over time and is typically interpreted alongside symptoms and other tests like CRP.