Does positive RF factor interfere with TSH value ?

Created/Updated: #dec2024

Research by : Shaikh N. Nayeemuddin, Akash Panigrahi et al.
Summary by: GPT-4o
Edited and Curated by : Dr. Om J Lakhani

  1. Title: Heterophilic Interference of Rheumatoid Factor in TSH Immunometric Assay: A Cross-Sectional Observational Study

  2. Authors: Shaikh N. Nayeemuddin, Akash Panigrahi et al.

  3. One-line summary: This study aimed to investigate whether rheumatoid factor (RF) causes heterophilic interference in thyroid-stimulating hormone (TSH) immunoassays in patients with rheumatoid arthritis (RA).

  4. Six key points:

i. 84 newly diagnosed RF-positive RA patients underwent TSH, free T4, anti-TPO, and four tests to screen for TSH interference (chemiluminescence technique (CLIA) on Siemens Immulite 1000 platform)
ii. 10 samples showed loss of linearity on dilution studies, indicating potential interference.
iii. 5 cases exhibited interference after heterophile blocker treatment.
iv. 1 patient had diagnostic interpretation discordance on a second assay platform.
v. No sample on polyethylene glycol (PEG) precipitation suggested antibody interference. vi. In most cases, the suspected interference did not affect clinical decision-making.

  1. Practical take-home message: RF can cause heterophilic interference in commercial TSH immunoassays, which can be identified through dilution studies or heterophile blocker treatment. However, this interference does not significantly impact clinical decision-making in most situations.

  2. Citation (Vancouver format): Nayeemuddin SN, Panigrahi A, Bhattacharjee R, Chowdhury S. Heterophilic interference of rheumatoid factor in TSH immunometric assay: A cross-sectional observational study. Indian J Endocr Metab 2024;28:29-34.