A solid phase colorimetric assay to detect very low levels of albumin, the major blood plasma protein which is responsible for much of the plasma colloidal osmotic pressure and serves as a transport protein for large organic anions such as fatty acids and bilirubin, in a specified sample of urine, in which a strip of paper, or of plastic with one or more attached pads of paper, impregnated with a reagent that reacts with albumin is dipped into the urine sample, allowed to react for a specified period of time and then the results are assessed by a visual comparison with a standard chromatic/color scale.