Q. I am a 53-year-old male weighing 80 kg and height 173 cm. I have been diagnosed with diabetic nephropathy and with cardio-myopathy with ejection fraction 40%. In the last three tests, my ESR reading is 106-108. My CBC showed a rise in eosinophil to 10,900. Is chronic kidney disease (CKD) the cause of high ESR? If not, what could be the cause of this?
Erythrocyte sedimentation rate (ESR) is a non-specific screening test for various diseases. It is a simple and inexpensive test that measures the distance that red blood cells have fallen after one hour in a vertical column of anti-coagulated blood under the influence of gravity. The amount of fibrinogen (a blood protein) in the blood directly correlates with the ESR. Although many studies have been done, an increased ESR remains a nonspecific finding. The use of the ESR as a screening test in asymptomatic persons is limited by its low sensitivity and specificity as it is affected by many variables. Women tend to have higher ESR values, as do the elderly. Obese people too tend to have raised ESR for some unknown reason though this is not thought to have any clinical significance.
Any condition that increases fibrinogen levels (e.g., pregnancy, diabetes mellitus, end-stage renal failure, heart disease, collagen vascular diseases, malignancy) may elevate the ESR. In anaemia the ESR rises as the speed of the upward flow of plasma is altered so that red blood cell aggregates fall faster. Macrocytic (larger) red cells with a smaller surface-to-volume ratio also settle more rapidly.
A decreased ESR is associated with a number of blood diseases in which red blood cells have an irregular or smaller shape that causes slower settling. Patients with polycythaemia (increased number of red blood) have a low ESR as the large number of cells present decrease the compactness of the red cell clump. Markedly increased numbers of white blood cells as seen in some leukaemias also lowers the ESR.
Earlier, this test was commonly used as an index of disease activity in patients who had certain disorders. With the development of more specific methods of evaluation, the ESR has remained an appropriate measure of disease activity or response to therapy for only a few diseases like temporal arteritis, polymyalgia rheumatica, rheumatoid arthritis and, possibly, Hodgkins disease. The ESR remains an important diagnostic criterion for only two diseases: polymyalgia rheumatica and temporal arthritis. No obvious cause is apparent in fewer than 2 percent of patients with a markedly elevated ESR. An elevated ESR in the absence of other findings should not prompt an extensive laboratory or radiographic evaluation but a mild to moderately raised one without any obvious cause should be repeated after a few months rather than an expensive search for occult disease.
The raised ESR in your case is likely due to the underlying renal disorder. To rule out an infection, other tests like the total leukocyte count, peripheral smear examination along with a meticulous clinical examination are required.