Polyuria: A physiological and illustrated point of view

Abstract

The magnitude of polyuria is tightly dependent on the amount of water and osmole intakes as well as the impairment of kidneys to concentrate urine. Thus, we can identify primary polydipsia and potomania, osmotic polyuria related to urinary increased excretion of endogenous or exogenous osmoles, concentrating defects due to corticopapillary impairment or a decreased plasma vasopressin concentration. Interpretation of fasting (i.e. after water restriction) blood and urine samples followed by a desmopressin administration allows a rapid diagnosis in most cases. Plasma vasopressin measurement during water restriction altogether with brain CT-scan may represent additional useful tools in complex cases.