Medication Interference with Rheumatoid Factor (RF) Testing – Evidence Summary

1. Absence of Drug‑Induced False‑Positive RF Results

• Current guidelines and high‑quality studies do not identify any medication that produces a false‑positive rheumatoid factor test in patients being evaluated for rheumatoid arthritis. 1

2. Drugs That Interfere With Other Laboratory Assays (Not RF)

• β‑blockers, ACE inhibitors, diuretics, and oral contraceptives have been shown to alter the aldosterone‑renin ratio used for primary aldosteronism screening, but these agents have no documented effect on RF immunoassays. 1, 2, 3

3. Demographic and Clinical Factors Not Affecting RF Results

• Age ≥ 65 years can modify autoimmune marker levels and influence aldosterone‑renin testing, yet there is no evidence that advanced age changes RF test outcomes. 3
• Chronic kidney disease may impact a variety of laboratory measurements, but studies have not reported any specific interference with RF testing. 1, 3