Approach to Elevated ESR with Normal CRP

Understanding the Discordance

Anemia directly increases ESR independent of inflammation, according to the American College of Physicians, in patients with elevated ESR and normal CRP 1
Renal insufficiency/azotemia is associated with a >3-fold increased risk of this discordance pattern, as reported by the National Kidney Foundation 1

The American Gastroenterological Association recommends confirming CRP threshold used (typically <5-6 mg/L is normal) to verify the CRP is truly normal 2, 3
CRP is the preferred marker for active inflammation because it rises and falls more rapidly with disease activity, according to the American College of Rheumatology 4

The American College of Physicians suggests assessing hemoglobin/hematocrit for anemia in patients with elevated ESR and normal CRP 1
Measuring serum creatinine and calculating GFR is recommended to check renal function, as advised by the National Kidney Foundation 1
Repeat ESR and CRP in 2-4 weeks to determine if elevation is persistent or transitory, according to the American College of Physicians 1

Women have higher baseline ESR values than men, and ESR normally increases with advancing age, as reported by the American Geriatrics Society 1
Consider age-adjusted reference ranges (>20 mm/h in men, >30 mm/h in women for general screening), as recommended by the American College of Physicians 1

Consider targeted evaluation for giant cell arteritis if patient has specific symptoms (new headache, jaw claudication, visual symptoms) and ESR >40 mm/h, which has 93.2% sensitivity, according to the American College of Rheumatology 1
Evaluate for polymyalgia rheumatica if patient has bilateral shoulder/hip girdle pain with morning stiffness >45 minutes, as advised by the American College of Rheumatology 1
Investigate for occult malignancy or infection if patient has constitutional symptoms (fever, weight loss, night sweats), according to the American Cancer Society 1

The American Gastroenterological Association recommends against using ESR to screen for IBD, as both ESR and CRP have poor sensitivity (54-78% for ESR, 73% for CRP) 3, 5