Diabetes insipidusBMJ 2019; 364 doi: https://doi.org/10.1136/bmj.l321 (Published 28 February 2019) Cite this as: BMJ 2019;364:l321
- Miles Levy, consultant endocrinologist1,
- Malcolm Prentice, consultant endocrinologist2,
- John Wass, consultant endocrinologist3
- 1Department of Endocrinology, University Hospitals of Leicester, Leicester, UK
- 2Department of Endocrinology, Croydon University Hospital, London, UK
- 3Department of Endocrinology, Oxford University Hospital NHS Foundation Trust, Oxford, UK
- Correspondence to M Levy firstname.lastname@example.org
What you need to know
In patients with polyuria, diabetes insipidus is very unlikely if urine osmolality is >700 mOsmol/kg
Patients with central diabetes insipidus who are admitted to hospital should have specialist input and safeguards in place to ensure that desmopressin is not omitted
Intercurrent illness with hypernatraemia in a patient with diabetes insipidus should be managed as a medical emergency
Diabetes insipidus is a rare but treatable condition that typically presents with extreme thirst (polydipsia) together with the passing of large amounts of dilute urine (polyuria). Distinguishing these symptoms from those of primary polydipsia, diabetes mellitus, and causes of urinary frequency without polyuria can be challenging. Diabetes insipidus is caused by a problem with vasopressin production in the pituitary gland (central diabetes insipidus), or action of vasopressin in the kidneys (nephrogenic diabetes insipidus). Desmopressin, an analogue of vasopressin, is an effective treatment for cranial diabetes insipidus. Between 2009 and 2016 there were four reported deaths in England resulting from omission of desmopressin, and a further 56 reported incidents where dosing errors resulted in harm.1 This Practice Pointer offers an approach to diagnosing suspected diabetes insipidus, and guidance on managing people with diabetes insipidus who have intercurrent illness or require hospital admission.
What is diabetes insipidus?
Diabetes insipidus is rare, with a prevalence of 1 in 25 000.2 Central diabetes insipidus usually results from pituitary pathology,3 either as a result of infiltrative or inflammatory pathology, or following surgery for a pituitary tumour, but may also be due to a congenital defect in the production of arginine vasopressin.3 Nephrogenic diabetes insipidus is usually caused by electrolyte disturbance, renal disease, or drug toxicity (commonly lithium2).
Arginine vasopressin causes water reabsorption at the collecting ducts of the kidney (fig 1). Deficiency of or resistance to the hormone, as seen in diabetes insipidus, leads to excessive water …