Q: I am a 44-year-old woman. I have a blood test done every six weeks as I take 10 mg methotrexate for psoriatic arthritis, which at present is extremely well controlled. I have had my Hb, LFT, Urine R&ME and ESR done. My ESR over the last few months has been 5 mm/hour. My last ESR reading was 1 mm/hour. The doctor marked my results as satisfactory and said he doesn't need to examine me further, but I am a little concerned as I think it is low. Is my ESR value normal?

A:The Erythrocyte Sedimentation Rate (ESR) is a simple and inexpensive laboratory test that clinicians have used for decision making for over fifty years. However, the usefulness of this test has decreased as new methods of evaluating disease have been developed. Raised ESR remains helpful in the specific diagnosis of a few conditions, including temporal arteritis, polymyalgia rheumatica and, possibly, rheumatoid arthritis. It is useful in monitoring these conditions and may predict relapse in patients with Hodgkin's disease. Normal ESR value for women under 50 years old is less than 20 mm/hour and women more than 50 years old is less than 30 mm/hour. As the ESR is 1 in your case, it falls within the normal range. Hence, I would reassure you not to worry about this low level ESR.