Hyposthenuria

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Sections available in full article Introduction, Presenting signs, Acute presentation, Special risks (e.g. anesthetic), Pathogenesis, Etiology, Predisposing factors, Pathophysiology, Diagnosis, Presenting problems, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Initial symptomatic treatment, Standard treatment, Monitoring, Subsequent management, Sources, Publications, Vetstream contributor(s),
Contributors Mr Daniel H Lewis MA VetMB CertVA MRCVS
Dr Jana Gordon DVM DACVIM

Introduction

  • Definition : urine Specific Gravity <1.008; Urine Osmolality <300 mOsm/kg.
  • Hyposthenuria implies urine with an osmolality less than that of plasma and indicates decreased reabsorption of water by the kidneys and a normal renal ability to dilute urine.
  • Urine concentration is determined by the action of antidiuretic hormone (ADH) upon the principal cells of the cortical and medullary collecting ducts, and is dependent upon the presence of a hyperosmotic medullary interstitium.

Diagnosis

Clinical signs

  • Polyuria/polydipsia.
  • Dependent upon underlying cause (see Differential Diagnosis).

Diagnosis

Differential diagnosis

  • Pyometra Pyometra.
  • Pyelonephritis Pyelonephritis.
  • Hyperadrenocorticism Hyperadrenocorticism.
  • Hypoadrenocorticism Hypoadrenocorticism.
  • Diabetes insipidus Diabetes insipidus (central or nephrogenic).
  • Renal tubular injury/early renal failure.
  • Hepatic failure.
  • Primary polydipsia.
  • Hyperthyroidism.
  • Hypercalcemia (of malignancy, hyperparathyroidism, renal failure, hypoadrenocorticism, hypervitaminosis D, granulomatous disease, physiological in young animals).
  • Fanconis syndrome Fanconis syndrome /primary renal glycosuria Urinalysis: glucose.
  • Renal medullary washout (following intravenous fluid therapy or urinary outflow obstruction relief).

Sources

Publications

Refereed papers

  • Recent references from PubMed.

Other sources of information

  • DiBartola S (2006) Disorders of Sodium and Water: Hypernatraemia and Hyponatraemia. In: Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice.pp 47-79. Ed S. DiBartola, Saunders Elsevier.
  • Archer J (2005) Urine analysis. In: BSAVA Manual of Canine and Feline Clinical Pathology. pp 149-168. Eds E.Villiers & L.Blackwood, BSAVA Publications.
  • Eaton D C, Pooler J P (2004) Vanders Renal Physiology. Lange Medical Books/McGraw-Hill.

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