Antidiuretic hormone (ADH) is a hormone that helps kidneys manage the amount of water in the body. The ADH test measures how much ADH is in blood. This test is often combined with other tests to find out what is causing too much or too little of this hormone to be present in the blood.
ADH level testing
The normal range for ADH is 1-5 picograms per milliliter (pg/mL). Normal ranges can vary slightly among different laboratories. ADH levels that are too low or too high can be caused by a number of different problems.
Too little ADH in your blood may be caused by compulsive water drinking or low blood serum osmolality, which is the concentration of particles in your blood.
A rare water metabolism disorder called central diabetes insipidus is sometimes the cause of ADH deficiency. Central diabetes insipidus is marked by a decrease in either the production of ADH by your hypothalamus or the release of ADH from your pituitary gland.
Common symptoms include excessive urination, which is called polyuria, followed by extreme thirst, which is called polydipsia.
People with central diabetes insipidus are often extremely tired because their sleep is frequently interrupted by the need to urinate. Their urine is clear, odorless, and has an abnormally low concentration of particles.
Central diabetes insipidus can lead to severe dehydration if it’s left untreated. Your body won’t have enough water to function.
This disorder is not related to the more common diabetes, which affects the level of the hormone insulin in your blood.
When there’s too much ADH in your blood, syndrome of inappropriate ADH (SIADH) may be the cause. If the condition is acute, you may have a headache, nausea, or vomiting. In severe cases, coma and convulsions can occur. Increased ADH is associated with: leukemia and other cancers Guillain-Barré syndrome multiple sclerosis epilepsy acute intermittent porphyria, which is a genetic disorder that affects your production of heme, an important component of blood cystic fibrosisemphysema tuberculosis HIV AIDS Dehydration, brain trauma, and surgery can also cause excess ADH.
Nephrogenic diabetes insipidus is another very rare disorder that may affect ADH levels. If you have this condition, there’s enough ADH in your blood, but your kidney can’t respond to it, resulting in very dilute urine. The signs and symptoms are similar to central diabetes insipidus. They include excessive urination, which is called polyuria, followed by extreme thirst, which is called polydipsia. Testing for this disorder will likely reveal normal or high ADH levels, which will help distinguish it from central diabetes insipidus.
Nephrogenic diabetes insipidus is not related to the more common diabetes mellitus, which affects the level of insulin hormone in the blood.
Abnormally high levels of ADH may mean you have:
- a brain injury or trauma
- a brain tumor
- a brain infection
- a central nervous system infection or tumor
- a lung infection
- small cell carcinoma lung cancer
- fluid imbalance after surgery
- syndrome of inappropriate ADH (SIADH)
- a stroke
- nephrogenic diabetes insipidus, which is very rare
- acute porphyria, which is very rare
Abnormally low levels of ADH may mean:
- pituitary damage
- primary polydipsia
- central diabetes insipidus, which is rare
An ADH test alone is usually not enough to make a diagnosis. Your doctor will probably need to perform a combination of tests. Some tests that may be performed with an ADH test include the following:
- An osmolality test is a blood or urine test that measures the concentration of dissolved particles in your blood serum and urine.
- An electrolyte screening is a blood test that’s used to measure the amount of electrolytes, usually sodium or potassium, in your body.
- A water deprivation test examines how frequently you urinate if you stop drinking water for several hours.
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