title: Polyuria in childhood.
abstract: Polyuria may result from either a water or a solute diuresis. Although the history and physical examination may provide clues to the cause of the polyuria, the definitive diagnosis requires laboratory tests which focus on the osmolality of the urine and serum in combination with the urine volume and the rate of excretion of osmoles. An isoosmolar or hyperosmolar urine is found in children with a solute diuresis or in normal children, whereas a hypoosmolar urine is found in children with a water diuresis. In the latter case, a low serum osmolality suggests primary polydipsia whereas a high serum osmolality suggests antidiuretic hormone (ADH) deficiency or insensitivity. A water deprivation test is necessary when the initial evaluation fails to establish the cause of polyuria. A vasopressin test enables the differentiation between neurogenic and nephrogenic diabetes insipidus (DI).
authors.affiliation: Department of Pediatrics, University of Calgary, Alberta, Canada.
authors.forename: A K
authors.initials: AK
authors.lastname: Leung
authors.forename: W L
authors.initials: WL
authors.lastname: Robson
authors.forename: M L
authors.initials: ML
authors.lastname: Halperin
mesh_terms: D002648:Child; D003937:Diagnosis, Differential; D006801:Humans; D011141:Polyuria / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy