Antidiuretic Hormone (ADH)
|See Also||Lab Tests|
Antidiurectic Hormone, also known as ADH, Vasopression or Arginine Vasopression helps detect, diagnose, and determine the cause of antidiuretic hormone (ADH) deficiency or excess. It is also used to investigate high and low blood sodium levels, and to distinguish the two types of diabetes insipidus. The ADH test is usually conducted when a patient presents with hyponatremia or has persistent thirst, frequent urination, and dehydration., 
- This test measures the amount of antidiuretic hormone in the blood.
- ADH is a hormone produced by the hypothalamus and is stored in the posterior pituitary gland.
- ADH functions to regulate water balance in the body by controlling the amount of water the kidneys reabsorb.
- If there is too little ADH or the kidneys do not properly respond to the ADH, then too much water is lost through the kidneys, the urine produced is more dilute than normal, and the blood becomes more concentrated. This can cause excessive thirst, frequent urination, dehydration, and high blood sodium (hypernatremia). It there is too much ADH, then water is retained, blood volume increases, and the person may experience nausea, headaches, disorientation, lethargy and hyponatremia.
Typically no preparation is needed unless the test is being performed as part of a water deprivation ADH stimulation test or a water loading ADH suppression test.
- Factors which can cause increased levels: standing for long periods of time, levels are naturally higher at night, pain, increased stress and exercise
- Drugs: Barbiturates, desipramine, histamine, morphine, nicotine, amitriptyline, carbamazepine, drugs that promote ADH action which include acetaminophen, metformin, tolbutamide, aspirin, theophylline, and non-steroidal anti-inflammatory drugs.
- Factors which can cause decreased levels: hypertension, lying down
- Drugs: Ethanol, lithium, and phenytoin
High levels indicate:
- Syndromes of Inappropriate ADH production (SIADH)
- Cancers (leukemia, lymphoma, lung cancer, pancreatic, bladder, and brain cancer)
- Guillain-Barre syndrome
- Multiple sclerosis
- Acute intermittent porphyria
- Cystic fibrosis
- Nephrogenic diabetes insipidus
- greatly increased ADH may be seen with systemic cancers that produce ADH
Low levels indicate:
- Central diabetes insipidus
- Compulsive water drinking
- Low serum osmolality
- Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.
- Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain.