<prompt> Which of the following promotes rouleaux formation?Zeta potential on RBC membraneFibrinogenAlbuminBiconcave shape of RBC  <response>: When in circulation, the negative charge on the RBC membrane or zeta potential does not allow RBCs to clump. When blood is made to stand in a veical tube, the asymmetric macromolecules in the plasma overcome the zeta potential, so as to form the rouleaux and settling down of the RBC clumps. Fibrinogen and gamma-globulins are the examples of such asymmetric macromolecules. Plasma albumin retards the rouleaux formation. Hence, in nephrotic syndrome, in which the albumin levels fall, there is a rise in ESR. 