Arginine vasopressin deficiency or resistance (Diabetes insipidus)

Arginine vasopressin deficiency (AVP-D; previously known as central diabetes insipidus) or resistance (AVP-R; previously known as nephrogenic diabetes insipidus) are disorders characterised by polydipsia, polyuria, and formation of inappropriately hypotonic (dilute) urine due to renal water loss.

AVP-D occurs due to reduced synthesis or release of AVP from the hypothalamo-pituitary axis. AVP-R occurs due to renal insensitivity to AVP.

Recognised risk factors for AVP-D include pituitary surgery, craniopharyngioma, infiltrative pituitary stalk lesions, traumatic brain injury, subarachnoid haemorrhage, congenital hypothalamo-pituitary defects, autoimmune disorders, and Wolfram syndrome. Risk factors for AVP-R include lithium therapy, chronic kidney disease, and chronic hypercalcaemia or hypokalaemia. Genetic mutations are responsible for inherited forms of both types.

Both AVP-D and AVP-R may be associated with hypernatraemia, and this may present as a medical emergency. Significant hypernatraemia usually only occurs in these conditions in association with adipsia or impaired access to free water.

Treatment goals are correction and stabilisation of water deficit and electrolyte balance, together with reduction in symptoms of excessive urinary water loss and thirst. In AVP-D, the synthetic AVP analogue desmopressin (also known as DDAVP) is the treatment of choice. AVP-R is treated with an adequate fluid intake; salt restriction and diuretics may help reduce polyuria.

The regulation of water is tightly controlled by the hormone arginine vasopressin (AVP), also known as antidiuretic hormone (ADH), which is produced by the hypothalamus and secreted via the posterior pituitary. AVP-D occurs due to an absolute or relative deficiency of AVP, while AVP-R arises from resistance to the action of AVP within the renal collecting ducts. Clinically they manifest as polydipsia, polyuria, and hypotonic urine due to renal water loss.[1]Christ-Crain M, Bichet DG, Fenske WK, et al. Diabetes insipidus. Nat Rev Dis Primers. 2019 Aug 8;5(1):54. http://www.ncbi.nlm.nih.gov/pubmed/31395885?tool=bestpractice.com ​ This was previously referred to as diabetes insipidus; however, due to the confusion with diabetes mellitus, the terms AVP-D and AVP-R are preferred.​[2]Arima H, Cheetham T, Christ-Crain M, et al. Changing the name of diabetes insipidus: a position statement of the working group for renaming diabetes insipidus. J Clin Endocrinol Metab. 2022 Dec 17;108(1):1-3. https://www.doi.org/10.1210/clinem/dgac547 http://www.ncbi.nlm.nih.gov/pubmed/36355385?tool=bestpractice.com