What Lab Tests Are Used to Diagnose Diabetes Insipidus?

Lab tests that measure urine concentration and hormonal levels can help diagnose diabetes insipidus, a condition that causes excessive urination.

Diabetes insipidus is a condition that causes the body to produce too much urine. People with this condition can pass up to 20 quarts of urine each day, leading to dehydration.

To diagnose the condition, your doctor may order tests like water deprivation and vasopressin. These can determine the cause of your high amounts of urination.

Read on to learn more about lab tests for diabetes insipidus.

Water deprivation test

Also called a urine gravity test, a water deprivation test can help doctors find the cause of diabetes insipidus and confirm a diagnosis.

During this test, you’ll need to go several hours without drinking any liquids. Then they’ll measure how much urine you pass, changes in your weight, the composition of your urine, and differences in your blood markers.

Vasopressin test

People with diabetes insipidus often have too little of a hormone called vasopressin . This hormone is also sometimes called antidiuretic hormone, which means it helps your kidneys balance out the amount of fluid in your body.

During a vasopressin test, you’ll receive a medication that causes your body to produce vasopressin. Doctors will then be able to measure how your body responds.

They’ll also measure how much of a hormone called copeptin your body produces. Copeptin levels typically rise when vasopressin levels rise, so it can be useful in determining vasopressin levels.

The results of this test can help determine whether diabetes insipidus or another condition is causing your polyuria.

Other tests

Doctors can order several other tests to help diagnose diabetes insipidus. These might include:

• Urinalysis: A urinalysis can measure the glucose (sugar) and other substances present in your urine. It can help doctors differentiate diabetes insipidus from diabetes mellitus.
• Blood tests: Blood tests can look for substances, such as antidiuretic hormone, in your blood that might indicate diabetes insipidus.
• Magnetic resonance imaging (MRI): An MRI is an imaging test that can give a closer look at your pituitary and hypothalamus glands. If either of your glands have damage, it may indicate diabetes insipidus.

Types of diabetes insipidus

There are multiple types of diabetes insipidus, and testing can help doctors determine which type you have.

Some of the types include:

• Central diabetes insipidus: A lack of vasopressin causes this.
• Nephrogenic diabetes insipidus: This form happens when your kidneys can’t use the vasopressin your body makes.
• Dipsogenic diabetes insipidus: This is a result of an error that happens in your hypothalamus, the part of your brain that links the endocrine and nervous systems.
• Gestational diabetes insipidus: This type develops during pregnancy and resolves shortly after.

Read more about the different forms of diabetes insipidus .

What lab values indicate diabetes insipidus?

Specific lab results can’t indicate diabetes insipidus — instead, healthcare professionals use a range of tests and biomarkers to diagnose it.

Other values that indicate you may have the condition include:

• low levels of antidiuretic hormone
• low levels of copeptin
• low urine osmolality (how concentrated your urine is)

When to contact your doctor

Diabetes insipidus causes symptoms such as the need to urinate throughout the day, passing large amounts of urine, and extreme thirst. These can all lead to dehydration, which can become a medical emergency.

Symptoms of dehydration can include:

• dry mouth
• thirst
• fatigue
• lightheadedness
• nausea
• fainting
• difficulty with everyday tasks

Symptoms of severe dehydration can include:

• sluggishness
• confusion
• dizziness

It’s important to seek urgent medical care if you’re experiencing symptoms of severe dehydration. This can lead to seizures, brain damage, and even death.

Learn more about dehydration .

Treatment for diabetes insipidus

The primary treatment for diabetes insipidus is staying hydrated. Drinking enough liquid to prevent dehydration can prevent serious complications.

Still, this can be difficult and can disrupt sleep or work. Your doctor may suggest additional measures you can take to keep yourself hydrated, such as:

• sucking on ice throughout the day
• taking a medication called desmopressin
• taking diuretic medications
• balancing calcium or potassium in the body with electrolytes

The bottom line

Diabetes insipidus causes excessive urine production and can lead to dehydration.

To help diagnose it, doctors can order tests such as water deprivation and vasopressin tests along with a urinalysis, blood work, and an MRI. Once diabetes insipidus is diagnosed, they can recommend a course of treatment.

If you think you have symptoms of diabetes insipidus, it’s a good idea to contact your doctor.