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Health condition

Diabetes insipidus (AVP deficiency)

Diabetes insipidus - now called AVP deficiency - is a failure of the water-conserving hormone vasopressin, causing extreme thirst and the passing of large volumes of dilute urine. It is unrelated to diabetes mellitus.

Key points

What matters most, at a glance.

The essentials in plain English - symptoms, when to seek help, who to see and what treatment looks like.

  • Hallmarks: passing very large volumes of pale urine day and night, with relentless thirst

  • Completely different from sugar diabetes despite the shared historical name

  • Causes include pituitary surgery, head injury, tumours and inflammation; a kidney-resistant form also exists

  • Diagnosed with paired blood and urine tests, a water deprivation test or copeptin measurement

  • Treated effectively with desmopressin; managed by an endocrinologist

Understanding it

About Diabetes insipidus (AVP deficiency), and what to do next.

Vasopressin (AVP) tells the kidneys to conserve water; without it, they cannot, and the body pours out litres of dilute urine - often 5 to 15 litres a day - with thirst so severe that people wake repeatedly at night to drink. The renamed condition, AVP deficiency, usually stems from damage to the pituitary region; a separate form, AVP resistance, arises when the kidneys stop responding, sometimes due to lithium therapy.

Testing distinguishes it from the far more common habitual excessive drinking, and desmopressin - a synthetic replacement as a tablet, melt or spray - restores normal life. Patients also carry alerts, because being denied water (for example when unwell in hospital) is genuinely dangerous. Most people start with their GP, who can refer to an endocrinologist. NHS routine referrals often take 20-45+ weeks depending on where you live, while a private consultation is typically available within about two weeks.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If in doubt, see them.

Frequently asked

Common questions about Diabetes insipidus (AVP deficiency).

Quick, plain-English answers to what people ask us most.

  • What is diabetes insipidus (AVP deficiency)?

    Diabetes insipidus, now increasingly called AVP (arginine vasopressin) deficiency, is a failure of the water-conserving hormone vasopressin, causing extreme thirst and the production of large volumes of dilute urine.

  • What causes AVP deficiency?

    It's caused by insufficient production of vasopressin by the pituitary gland (central AVP deficiency), often due to pituitary or hypothalamic damage from tumours, surgery, injury, or other causes, though sometimes no clear cause is found.

  • What are the symptoms of AVP deficiency?

    The hallmark symptoms are excessive thirst (polydipsia) and passing large volumes of very dilute urine (polyuria), often disrupting sleep due to the need to urinate frequently through the night.

  • Is AVP deficiency dangerous?

    If untreated, it can lead to dehydration and dangerous electrolyte imbalances, particularly if fluid access is restricted for any reason, so proper diagnosis and treatment matter significantly for safety.

  • How is AVP deficiency treated?

    Treatment typically involves desmopressin, a synthetic form of vasopressin, which effectively replaces the missing hormone and allows the kidneys to concentrate urine normally, controlling both thirst and excessive urination.

  • Can AVP deficiency be cured?

    This depends on the underlying cause - if caused by a treatable pituitary problem, addressing that may resolve the issue, but many cases are managed long-term with desmopressin replacement rather than being fully cured.

  • AVP deficiency vs AVP resistance - what's the difference?

    AVP deficiency (central diabetes insipidus) means the body doesn't produce enough vasopressin, while AVP resistance (nephrogenic diabetes insipidus) means vasopressin is produced normally but the kidneys don't respond to it properly - the distinction determines whether desmopressin will be effective.

  • How is AVP deficiency diagnosed?

    Diagnosis typically involves specific tests such as a water deprivation test, alongside blood and urine testing, and sometimes pituitary imaging to identify an underlying cause, performed by an endocrinologist.

  • How long does desmopressin treatment need to continue?

    Treatment is often needed long-term or lifelong for central AVP deficiency, since the underlying hormone production doesn't typically recover, though the specific dose and formulation may be adjusted over time.

  • When should I see a specialist about possible AVP deficiency?

    See an endocrinologist if you have persistent excessive thirst and very frequent urination, particularly if disrupting sleep. A private endocrinology consultation is often available within about two weeks.