Antidiuretic Hormone (ADH, Vasopressin, Arginine Vasopressin Hormone)

Sample
- This test is done on the venous blood sample, (Tube is prechilled).
- Plasma with EDTA is needed.
- Take the blood when a patient is in a sitting position and calm.
- Put the sample on ice.
- Or collect the sample in prechilled vials.
- Separate plasma immediately in the refrigerated centrifuge, and freeze at -20 °C.
Purpose of the test
- ADH is done in patients with diabetes insipidus.
- Advised in a patient with polyuria or polydipsia.
- This is also advised in hyponatremia.
- For the diagnosis of ectopic ADH production.
- This is advised in SIADH.
- This is also advised in psychogenic water intoxication.
Precautions
- Avoid glass syringe or collection tube which causes degradation of the ADH.
- Avoid dehydration, hypovolemia, and stress which may lead to increase ADH levels.
- Avoid overhydration and hypervolemia which may decrease the ADH level.
- Drugs like acetaminophen, cholinergic drugs, barbiturates, nicotine, estrogen, oral hypoglycemic agents, diuretics (thiazide), narcotics, and tricyclic antidepressants will lead to an increase the ADH.
- Drugs like alcohol, morphine antagonists, Dilantin, and beta-adrenergic agents will decrease the ADH level.
- The recent history of radioisotopes gives the wrong result.
Pathophysiology
- ADH is also called Vasopressin produced by the hypothalamus stored in the post. pituitary gland excreted in circulation.
- The osmolarity of the extracellular fluid control ADH release.
- Increased osmolarity stimulates the osmoreceptors in the hypothalamus which stimulates the ADH release.
- The major function of ADH controls:
- When ADH activity is present then a small volume of concentrated urine is excreted.
- When ADH is absent, then a large volume of dilute urine is excreted.
- Maintain water homeostasis.
- There is water reabsorption by the kidney and urine concentrated.
- ADH in sufficient quantity induces generalized vasoconstriction that leads to an increase in the arterial blood pressure.
- When ADH activity is present then a small volume of concentrated urine is excreted.
- ADH increases the release more water is reabsorbed from the distal and collecting tubule, it increases water reabsorption and leads to concentrated urine and more water in the blood circulation.
- ADH decreased level, less water reabsorbed (water is allowed to be excreted), leads to dilute urine and hemoconcentration.
- ADH release is stimulated by:
- The increase in serum osmolality.
- The decrease in intravascular blood volume.
- Higher secretion at night and with erect posture and exercise.
- Physical Stress, surgery, and even anxiety.
- Syndrome of inappropriate ADH secretion (SIADH) associated with high serum ADH levels.
- Paraneoplastic syndrome is seen in the case of ectopic production of the ADH like carcinoma of the lung, thymus, lymphoma, carcinoma of the pancreas, leukemia, urinary system, and intestine.
- This condition may also be seen in pulmonary tuberculosis and pneumonia.
- Other conditions are CNS tumors, infection, and trauma.
- Diagnosis of SIADH:
- The water load test means ADH suppression is used to differentiate the SIADH from the other causes of hyponatremia and or edematous conditions.
- Measure urine and serum osmolarity.
- Patients with SIADH secrete very little or none of the water overload.
- Urine osmolarity will be never <100 mmol/kg
- Urine/serum ratio is >100.
- Measure urine and serum osmolarity.
- The water load test means ADH suppression is used to differentiate the SIADH from the other causes of hyponatremia and or edematous conditions.
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Diabetes Insipidus occurs when:
- ADH is inadequate OR
- Kidneys are not responsive to ADH.
- The patient excretes a large volume of water in the urine.
- There is hemoconcentration and patients feel thirsty.
- Diabetes Insipidus may be:
- Neurogenic Diabetes insipidus. It is caused by:
- Trauma, tumor, or inflammation of the brain (Hypothalamus).
- ADH level is low.
- Surgical ablation of the pituitary gland or mass lesion.
- X linked recessive familial form.
- Nephrogenic diabetes insipidus. It is caused by:
- Renal collecting system unresponsiveness to ADH.
- ADH level is raised.
- Hypercalcemia.
- Hypokalemia.
- A very low protein diet.
- Lithium therapy.
- The release of long-standing obstruction.
- Aging may be associated with partial nephrogenic diabetes inspidus.
- Renal collecting system unresponsiveness to ADH.
- Diabetes insipidus criteria are:
- There are polyuria and polydipsia.
- Low urine osmolarity.
- Hypernatremia.
- Neurogenic Diabetes insipidus. It is caused by:
-
How to diagnose Diabetes inspidus:
- This is confirmed by overnight deprivation of water.
- Record the osmolarity before and after the administration of vasopressin.
- It is followed by the ADH (vasopressin) administration.
- In a healthy person urine osmolarity increases during water deprivation.
- Administration of vasopressin has to additional effect on urine concentration.
- In the case of neurogenic diabetes inspidus:
- No urine concentration in response to water deprivation.
- When vasopressin is given, then urine osmolarity increases.
- THE Serum ADH level is low.
- While in the case of nephrogenic diabetes inspidus:
- Urine cannot be concentrated in either case.
- There is no rise in the urine osmolality after water deprivation or after vasopressin administration.
- THE Serum ADH level is high.
- ADH presence leads to a small volume of concentrated urine.
- ADH absent leads to a large volume of diluted urine.
- ADH release is stimulated by:
- Increase in serum osmolality.
- A decrease in intravascular blood volume.
- Sleep
- At night.
- In erect position.
- with pain.
- In surgery.
- Physical Stress.
- High level of anxiety.
- Exercise.
- Chemical agents like catecholamine, opiates, nicotine, anesthesia drugs, barbiturates, and angiotensin ii.
- ADH release is inhibited by:
- The increase in plasma volume.
- The decrease in plasma osmolality.
- Alcohol.
- Phenytoin.
- Glucocorticoids
Normal
Source 2
- 1 to 5 pg/ mL or 1 to 5 ng/L.
- Or < 2.5 pg/mL.
- ADH suppression test (water load test):
- 65% of the water load is excreted in 4 hours.
- 80% of the water load is excreted in 5 hours.
- Urine osmolality in the second hour = ≤100 mmol/kg
- Urine to serum (U/S) osmolality ratio = >100 mmol/kg
- Urine specific gravity = <1.003
Another source
- 2 to 8 pg/mL
Source 4
- <2.5 pg/mL or <2.3 mmol/L
Increased ADH level is seen in:
- Hyperfunction of ADH state gives rise to Syndrome of inappropriate antidiuretic hormone secretion (SIADH).
- There is sustained release of ADH in the absence of a known cause.
- Central nervous system diseases like tumors or infection.
- Pulmonary tuberculosis or pneumonia.
- Lung cancer (ectopic ADH).
- Nephrogenic diabetes insipidus due to renal diseases.
- Myxedema.
- Physical stress like pain, trauma.
- Hypovolemia.
- Dehydration.
- Acute and intermittent porphyria.
- Guillain-barre syndrome.
Decreased ADH level is seen in:
- Hypofunction ADH gives rise to a polyuric state.
- Urine output is more than 2.5 L/day.
- Nephrogenic diabetes insipidus.
- Nephrotic syndrome.
- water intoxication (psychogenic polydipsia).
- Surgical ablation of the pituitary gland.
- Hypervolemia.
- Decreased serum osmolality.
- This polyuric state is divided into:
- Hypothalamic diabetes inspidus.
- Nephrogenic diabetes inspidus.
- Psychogenic polydipsia.