Arginine-Vasopressin Deficiency

Synonyms

central diabetes insipidus, neurogenic diabetes insipidus, cranial diabetes insipidus, neurohypophyseal diabetes insipidus,

Overview

Arginine-vasopressin (AVP) deficiency is a disorder where the body doesn’t produce enough of the hormone vasopressin, leading to the production of excessive, dilute urine and intense thirst. Also known as central diabetes insipidus, it results from the hypothalamus not making enough AVP or the body being unable to use it, disrupting the body’s water balance. Causes can be acquired (from head trauma, tumors, or surgery) or familial (inherited genetic changes), and in some cases, the cause remains unknown.  

Symptoms

The main symptoms of arginine-vasopressin (AVP) deficiency are excessive thirst (polydipsiap o l y d i p s i a) and frequent urination (polyuriap o l y u r i a), which can produce a large volume of very dilute urine. This leads to dehydration, which can cause dizziness, fatigue, confusion, low blood pressure, and headaches. In children, symptoms can include constipation, vomiting, and failure to thrive. 

Causes

Arginine-vasopressin (AVP) deficiency is most commonly caused by damage to the hypothalamus or pituitary gland from head injuries, brain tumors, or surgery. Other causes include infections (like meningitis or encephalitis), autoimmune diseases, and genetic disorders, while in about one-third of cases, the cause is unknown (idiopathic) and may involve the immune system attacking the body’s own cells. Less common causes include cancers that have spread to the brain or certain medications.  

Prevention

Preventing arginine-vasopressin deficiency (AVP-D) is difficult because many causes, such as genetic disorders or head injuries, cannot be prevented. However, some acquired forms of AVP-D and related conditions like arginine-vasopressin resistance (AVP-R) can be managed by addressing underlying causes, such as carefully monitoring and adjusting certain medications, treating high calcium or low potassium levels, and preventing or treating infections or obstructions that could damage the kidneys.  

Diagnosis

Diagnosis of arginine-vasopressin (AVP) deficiency involves a combination of physical exams, blood and urine tests, and a water deprivation test, with an MRI sometimes used to investigate the cause. A doctor will assess symptoms like excessive thirst and large volumes of dilute urine, then perform blood tests to check sodium and electrolyte levels, and a urinalysis to measure urine concentration. The definitive diagnostic step is often a water deprivation test, which shows the body’s inability to concentrate urine without adequate AVP. Newer, less uncomfortable tests like the copeptin test, which measures a marker for AVP, are also used.  

Prognosis

The prognosis for arginine-vasopressin deficiency (AVP-D) is generally good with proper treatment, allowing most people to lead normal lives, but the long-term outlook depends on the underlying cause and consistent management. Untreated AVP-D can lead to severe dehydration, electrolyte imbalances, and complications, while effective treatment helps control excessive urination and thirst. For certain causes, such as those related to cancer or other severe underlying diseases, the prognosis is tied to the outcome of the primary condition. 

Treatment

The main treatment for arginine-vasopressin (AVP) deficiency is desmopressin (DDAVP), a synthetic version of AVP, which can be administered as a nasal spray, tablet, or injection. Other treatments include thiazide diuretics and NSAIDs (like indomethacin) which may be used in combination with desmopressin to help reduce urine output, especially in cases of severe deficiency. Individuals with AVP deficiency also need to stay hydrated, but care must be taken not to overhydrate, as this can lead to low sodium levels (hyponatremia).