WHY IS ESR MORE INFORMATIVE THANASO TITRE, ANA LEVELS AND PRESENCE OF RHEUMATOID FACTOR IN A PATIENTWHO COMPLAINS OF JOINT PAINS?
Ex. Hon. Physician, Jaslok Hospital and Bombay Hospital, Mumbai, Ex. Hon. Prof. of Medicine, Grant Medical College and JJ Hospital, Mumbai 400 008.
If ESR is raised significantly, more than 35-40 mm, then the joint pains are definitely due to connective tissue disorder.
Rheumatoid factor if not done by nephilometry method is often negative and even if done properly is negative in patients having sero-negative rheumatoid arthritis.
ANA test done by ELISA method is often falsely positive and should ideally be done by WIL2-Hep2 method. Not only that, if ANA is reported abnormal but the ESR is not markedly raised, the test is likely to be falsely positive.
ASO titre is very often high, — though the patient has no rheumatic fever. This is a very common observation. A rising titre of ASO should be given importance if there is a history of fleeting or flitting joint pains with present or a past history of tonsillitis. Otherwise, it is a "non-specific" rise of the titre.
Till the pathologists start doing plasmo-viscosity levels which give much more information (but the test will be much more costly), ESR will remain as one of the best investigations in the differential diagnosis of poly-arthralgia or polyarthritis.
I am thankful to Dr. Sanjeev Amin for his comments.