Diabetes Insipidus: Role of the Kidneys

Diabetes mellitus' less well-known cousin could stem from kidney problems

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Unlike its better known cousin, diabetes mellitus, diabetes insipidus (DI) is far less understood. The term insipidus comes from the word insipid, which means "bland or tasteless" (as opposed to the word mellitus derived from "honey").  Hence the term diabetes insipidus refers to certain clinical findings that one would typically see in diabetes mellitus: like increased urination or increased thirst, but not where the urine has a sweet taste. 

DI therefore is an entirely different disease


In order to understand DI and its development, it is essential to understand how does our body handle water. One of the ways this happens is by the action of hormone called the antidiuretic hormone, or ADH. It is a hormone produced by the pituitary gland and acts on the kidneys. ADH is a hormone which determines how much water gets dumped out into your urine, and how much is retained in the body. When ADH levels are high, more water gets reabsorbed back into the body and very little is excreted into the urine. This leads to the urine looking dark and concentrated.  You might have noted this when you pass urine on a hot day (especially if you have not had enough water to drink).  Hence ADH is the body's protective mechanism against life-threatening dehydration.  Conversely, when the body has enough water, ADH production is minimized and hence the excess water in blood gets dumped into urine, thus making it clear and dilute.

Diabetes insipidus can therefore develop in two situations:

  • When the body does not make enough ADH, or
  • When enough ADH is made but it for some reason does not act appropriately on the kidneys (essentially the kidneys become resistant to ADH's action)

Regardless of the reasons, DI leads to a reduction in the body's ability to conserve water.

 Hence, it can lead to an inappropriate amount of water being lost in the urine, causing and worsening dehydration. This can become life-threatening in the worst case situation.


  1. As mentioned above, ADH is produced by the pituitary gland.  Hence any damage or disease of the pituitary gland can lead to diabetes insipidus as one of its features.This damage can be genetic, or occur from trauma or neurosurgery as well.
  2. However, the cause of the problem might also lie at the level of the kidneys.  Certain other diseases can damage the kidney and make it resistant to the actions of ADH.  These diseases include entities like polycystic kidney disease. Diseases that block the flow of urine from the kidney could do it, as can kidney damage that often occurs from long-term use of lithium for bipolar disease.
  3. Another entity called gestational diabetes insipidus can develop in pregnant women. In this case ADH is broken down by the placenta and can induce a temporary state of diabetes insipidus.


    The most common symptom seen in DI is increased thirst.  This again is very appropriate and is the reason why most patients with diabetes insipidus either do not see a life-threatening state of dehydration or sometimes don't even know they have diabetes insipidus.  Hence all the excess water that is being lost in the urine continues to get replaced because of the patient's ability to replace that by increased intake. Because of this, patient will also report increased urination.

    As long as water loss can be balanced by increased water intake, things should be fine.The real trouble however arises when the patient loses access to water for whatever reason or cannot sense thirst appropriately.  In this case, the body continues to lose water in the urine leading to a dangerous reduction in water content of the body as well as abnormal changes in the electrolyte levels in the blood (extremely high sodium level, for instance).


    Clinical features and lab tests including electrolyte levels, urine testing, and imaging studies help diagnose diabetes insipidus.  Disorders of the pituitary might be apparent on imaging of the brain.  A special test called the fluid deprivation test is often used to confirm the diagnosis.


    Depends on the cause.  Diabetes insipidus that occurs because of inadequate production of ADH from the pituitary can often be treated by replacement of ADH using a synthetic version of the hormone. The drug is called desmopressin and is similar to ADH and replaces lost function. However if the issue is ADH resistance, then replacing desmopressin might not be as helpful. In this case other medications including hydrochlorothiazide have been shown to help.

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