How is true diabetes insipidus and nephrogenic diabetes insipidus diagnosed?

What Is Diabetes Insipidus?

Diabetes insipidus is a rare condition that causes you to have an almost unquenchable thirst and your body to make a lot of urine that is colorless and odorless. Most people pee out 1 to 2 quarts a day. People with diabetes insipidus can pass between 3 and 20 quarts a day. The main types of diabetes insipidus include central, nephrogenic, and pregnancy-related.  

Diabetes Insipidus vs. Diabetes Mellitus

Diabetes insipidus is a different disease from diabetes mellitus. Their names are similar, but the only things they have in common is that they make you thirsty and make you pee a lot.

If you have diabetes insipidus, the hormones that help your body balance liquids don’t work. Only one in every 25,000 people gets this condition.

With diabetes mellitus (often shortened to “diabetes”), your body can’t use energy from food like it should. It’s far more common. Around 100 million Americans have type 1 or type 2 diabetes.

Symptoms of Diabetes Insipidus

Symptoms include:

• Severe thirst
• Peeing more than 3 liters a day (your doctor might call this polyuria)
• Getting up to go a lot at night
• Peeing during sleep (bed-wetting)
• Pale, colorless urine
• Low measured concentration of urine
• Preference for cold drinks
• Dehydration
• Weakness
• Muscle pains
• Crankiness

With dehydration, you might notice:

• Extreme thirst: often drinking more than 1 gallon of liquid per day
• Fatigue
• Feeling sluggish
• Dizziness
• Confusion
• Nausea
• Loss of consciousness

Symptoms in Infants and Children

Many of the symptoms are similar in younger people. In infants, watch for:

• Crankiness
• Slow growth
• Poor feeding
• Weight loss
• Fever
• Vomiting

In children, signs include:

• Drinking a lot of water
• Peeing often, sometimes every hour
• New bed-wetting or waking during the night to pee
• Dehydration
• Low energy

Diabetes Insipidus Causes

Your body makes a hormone called vasopressin in a part of your brain called the hypothalamus. It’s stored in your pituitary gland. Vasopressin tells your kidneys to hold on to water, which makes your urine more concentrated. (Vasopressin is also called antidiuretic hormone or ADH.)

When you’re thirsty or a little dehydrated, your vasopressin levels go up. Your kidneys absorb more water and put out concentrated urine. If you’ve had enough to drink, vasopressin levels fall, and what comes out is clear and diluted.

When your body doesn’t make enough vasopressin, the condition is called central diabetes insipidus. Anyone can get central DI, but it's not common. Only about 1 in every 25,000 people gets it.

If you make enough but your kidneys don’t respond to it the way they should, you have nephrogenic diabetes insipidus.

In either form, the result is the same. Your kidneys can't keep water, so even if you’re dehydrated, they'll put out a lot of pale urine.

Diabetes Insipidus Risk Factors

Changes in the genes that you inherit from your parents can make you more likely to get diabetes insipidus. This happens in 1% to 2% of cases.

Types of Diabetes Insipidus

• Central diabetes insipidus. You get this when damage to your hypothalamus or pituitary gland affects how your body makes or puts out vasopressin. Your kidneys remove too much fluid from your body, and you pee more. This damage can result from:
  • A tumor
  • A head injury
  • A blocked or bulging artery (aneurysm)
  • Diseases such as Langerhans cell histiocytosis
  • Infection
  • Inflammation
  • Surgery
• Nephrogenic diabetes insipidus. You get this when your kidneys don’t respond to vasopressin and take too much fluid from your bloodstream. Doctors don’t always know why it happens, but some causes include:
  • A blocked urinary tract
  • Chronic kidney disease
  • High levels of calcium in your blood
  • Low levels of potassium in your blood
  • Some medications, like lithium
• Gestational diabetes insipidus. This is very rare. You get this type only during pregnancy. Sometimes, a woman’s placenta -- the organ that gives oxygen and nutrients to your baby -- makes an enzyme that breaks down vasopressin. Other pregnant women make more prostaglandin, a hormone-like chemical that makes their kidneys less sensitive to vasopressin. Most cases of gestational diabetes insipidus are mild and don’t cause clear symptoms. The condition usually goes away after birth, but it might come back in another pregnancy.

How Is Diabetes Insipidus Diagnosed?

Your doctor will do a physical exam. A checkup may not show any signs of central DI, except maybe an enlarged bladder or symptoms of dehydration.

They’ll ask questions about your health history, including your family’s health. You might get a series of tests that include:

• Urinalysis. You’ll give a sample of your pee, and your doctor will send it to a lab to see whether it’s dilute or concentrated. They can also check for glucose, which can help them decide if you have diabetes insipidus or diabetes mellitus. You might need to collect your pee over a 24-hour period to see how much you’re putting out.
• Blood test. This will measure the electrolytes and glucose in your blood. This lets your doctor know if you have diabetes mellitus or diabetes insipidus. It may help them figure out which type.
• Fluid deprivation test. This measures the changes in your body weight, blood sodium, and urine concentration after you don’t drink anything for a while. There are two types:
  • Short-form fluid deprivation test. You stop drinking for a short time. You collect a sample and take it back to your doctor, who sends it to a lab.
  • Formal fluid deprivation test. You’ll have this done in a hospital so doctors can make sure you don’t get dehydrated. You’ll be weighed and give a sample every hour or two until:
    • Your blood pressure drops too low or you have a rapid heartbeat when you stand
    • You lose 5% or more of your starting body weight
    • Your urine concentration goes up a little bit over two or three measurements
• MRI. This test takes detailed pictures of your internal organs and soft tissues. The doctor uses it to see if there’s a problem with your hypothalamus or pituitary gland.
• Genetic screening. Your doctor may suggest this test if your family members have had problems with making too much urine.

Complications of Diabetes Insipidus

Diabetes insipidus that isn’t under control can make you more likely to have complications like:

• Dehydration. Diabetes insipidus makes it hard for your body to hold on to water. It’s easy to get dehydrated.
• Electrolyte imbalance. Electrolytes are minerals in your body with a tiny electric charge. When you lose too much water, your electrolyte levels can be abnormal. This might cause:
  • A headache
  • Feeling tired all the time (fatigue)
  • Irritability
  • Muscle pain
• Less sleep. Diabetes insipidus can lead to nocturia, a medical name for waking up in the night to pee. The result: a less restful night.

Diabetes Insipidus Treatment

First, your doctor will tell you to drink plenty of fluids. That will replace the constant loss of water. Other treatments depend on which type you have:

• Central diabetes insipidus. You’ll take medications like desmopressin (DDAVP). Desmopressin controls urine output, maintains fluid balance, and prevents dehydration. You take it two or three times a day. It usually comes as a nasal spray, tablets, or injections. There are also treatments to help these drugs work better.
• Nephrogenic diabetes insipidus can be harder to treat. If it’s caused by a drug, stopping the medicine helps. Other medicines may ease symptoms. These include indomethacin (Indocin) and diuretics like amiloride (Moduretic 5-50) or hydrochlorothiazide (Microzide). Though diuretics typically make you pee more, in this case, they help you make less urine. Sometimes, this condition goes away if you treat the cause.
• Gestational diabetes insipidus. You can take desmopressin while you’re pregnant. Your problems should go away after you have the baby.

Diabetes Insipidus Outlook

Diabetes insipidus doesn’t cause kidney failure or lead to dialysis. Your kidneys still do their main job, which is to filter your blood.

But you will be more prone to dehydration. Make sure you always have something to drink close by, especially when it’s hot or when you exercise. Carry your medication with you, and avoid situations where you can't get water. It's also a good idea to wear "medic alert" jewelry, or keep a note with you about your condition, so that health care workers know about it.