What does osmotic diuresis mean? In osmotic diuresis, certain solutes in the renal tubular fluid remain in the tubules because they are not re-collected, which can increase the concentration of solutes in the tubular fluid, and due to the effect of osmosis, some of the water is retained in the tubules, resulting in a decrease in the concentration of sodium in the tubules due to dilution, and a decrease in sodium reabsorption due to a decrease in the concentration gradient of sodium in the tubules and epithelial cells, and a decrease in the tubular more sodium ions in the tubular fluid, which in turn has to retain more water in the renal tubules, resulting in a water shock and an increase in urine volume and sodium chloride excretion. This is the factor of osmotic diuresis, in short, osmotic diuresis, which is an increase in urine volume due to the formation of high osmotic pressure in the plasma, glomerular filtrate, and tubular luminal fluid, which prevents the reabsorption of primary urine by the renal tubules.