: Background : Serum albumin concentration (SAC) is a prognostic factor that is affected by many factors such as postural change, liver function and food intake. Chronic kidney disease (CKD) patients excrete proteinuria, have low-protein diet, and receive glucocorticoid therapy. No one has evaluated the most influential factors on SAC in CKD patients. Methods : A retrospective study. Hospitalized CKD patients with less than 1 g/ gCreatinine proteinuria receiving glucocorticoid therapy (n=28), with 1 or more g/gCreatinine proteinuria not receiving glucocorticoid therapy (n=36), and with 1 or more g/gCreatinine proteinuria receiving glucocorticoid therapy (n =39) were enrolled. SAC, hemoglobin, proteinuria and blood pressure at the last outpatient check-up before hospitalization, on the second day of hospitalization, at the last laboratory examination before discharge, as well as at the first outpatient follow-up after discharge were analyzed. Results : SAC decreased on the second day of hospitalization and increased at the first outpatient follow-up significantly in all groups. Unexpectedly, the change of SAC was irrelevant to the amount of proteinuria. Conclusions : SAC was affected by not only proteinuria, but also postural change, physical activity, and food in CKD patients. SAC should be analyzed by standardizing a patient's condition during phlebotomy.