Antidiuretic hormone, plasma (ADH)
If serum osmolality > 290 mosm/kg H2O: 2–12 pg/mL
If serum osmolality <290 mosm/kg H2O: <2 pg/mL
Draw in two chilled tubes and deliver to lab on ice. Specimen for serum osmolality must be drawn at same time.
Antidiuretic hormone, also known as arginine vasopressin (AVP), is a hormone secreted from the posterior pituitary that acts on the distal nephron to conserve water and regulate the tonicity of body fluids.
Water deprivation provides both an osmotic and a volume stimulus for ADH release by increasing plasma osmolality and decreasing plasma volume.
Water administration lowers plasma osmolality and expands blood volume, inhibiting the release of ADH by the osmoreceptor and the atrial volume receptor mechanisms.
Increased in: Nephrogenic diabetes insipidus, syndrome of inappropriate antidiuretic hormone (SIADH), brain tumor. Drugs: nicotine, morphine, chlorpropamide, clofibrate, cyclophosphamide.
Normal relative to plasma osmolality in: Primary polydipsia.
Decreased in: Central (neurogenic) diabetes insipidus, water intoxication. Drugs: ethanol, phenytoin.
Test can help to diagnose diabetes insipidus and psychogenic water intoxication. Test very rarely indicated in diagnosis of SIADH: measurement of serum and urine osmolality usually suffices.
Patients with SIADH show decreased plasma sodium and decreased plasma osmolality, usually with high urine osmolality relative to plasma. These findings in a normovolemic patient with normal thyroid and adrenal function are sufficient to make the diagnosis of SIADH without measuring ADH itself.
Devuyst O et al. Physiopathology and diagnosis of nephrogenic diabetes insipidus. Ann Endocrinol (Paris) 2012;73:128. [PMID: 22503803]
Knepper MA et al. Molecular physiology of water balance. N Engl J Med 2015;372:1349. [PMID: 25830425]
Peri A et al. Management of euvolemic hyponatremia attributed to SIADH in the hospital setting. Minerva Endocrinol 2014;39:33. [PMID: 24513602]
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