Urinary excretion of aquaporin-2 in pathological states of water metabolism

Ann Med. 2000 Mar;32(2):90-3. doi: 10.3109/07853890009011757.


Aquaporin-2 (AQP-2) is an arginine vasopressin (AVP)-regulated water channel in renal collecting duct cells. Approximately 3 % of AQP-2 in collecting duct cells is excreted into urine. Urinary excretion of AQP-2 varies widely in different physiological conditions, and it has a positive correlation with plasma AVP levels. Urinary excretion of AQP-2 was significantly increased by the single injection of AVP in patients with central diabetes insipidus. The urinary excretion of AQP-2 was one-eighth over in patients with central diabetes insipidus and three times greater in patients with impaired water excretion than that in normal subjects. In a hypertonic saline test, the urinary excretion of AQP-2 promptly increased 6-12-fold in normal subjects, but remained low in patients with central diabetes insipidus. In addition, exaggerated urinary excretion of AQP-2 persisted after an acute water load in patients with impaired water excretion. These results indicate that urinary excretion of AQP-2 is a potent marker for the diagnosis of water metabolism disorders dependent on AVP.

Publication types

  • Comparative Study
  • Editorial
  • Review

MeSH terms

  • Animals
  • Aquaporin 2
  • Aquaporin 6
  • Aquaporins / administration & dosage
  • Aquaporins / genetics
  • Aquaporins / urine*
  • Biomarkers / analysis
  • Controlled Clinical Trials as Topic
  • Diabetes Insipidus / complications
  • Diabetes Insipidus / urine
  • Female
  • Heart Failure / complications
  • Heart Failure / urine
  • Humans
  • Liver Cirrhosis / complications
  • Liver Cirrhosis / urine
  • Male
  • Radioimmunoassay
  • Reference Values
  • Sensitivity and Specificity
  • Up-Regulation
  • Water / metabolism
  • Water-Electrolyte Imbalance / diagnosis*
  • Water-Electrolyte Imbalance / etiology
  • Water-Electrolyte Imbalance / urine*


  • AQP2 protein, human
  • Aquaporin 2
  • Aquaporin 6
  • Aquaporins
  • Biomarkers
  • Water