Davis's Lab & Diagnostic Tests
Antidiuretic Hormone
General
Synonym/Acronym:
Vasopressin, arginine vasopressin hormone, ADH.
Rationale
To evaluate disorders that affect urine concentration related to fluctuations of ADH secretion, such as diabetes insipidus and syndrome of inappropriate ADH secretion.
Patient Preparation
There are no food, fluid, or medication restrictions unless by medical direction. The patient should be encouraged to be calm and in a sitting position for specimen collection.
Normal Findings
Method: Radioimmunoassay.
| Age | Antidiuretic Hormone* | SI Units (Conventional Units × 0.923) | |||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Newborn | Less than 1.5 pg/mL | Less than 1.4 pmol/L | |||||||||||||||||||||||||||||||||||||||
| Child (normally hydrated) | 0.5–1.7 pg/mL | Less than 0.5–1.6 pmol/L | |||||||||||||||||||||||||||||||||||||||
| Adult (normally hydrated) | 1–5 pg/mL | 0.9–4.6 pmol/L | |||||||||||||||||||||||||||||||||||||||
| *Conventional units. | |||||||||||||||||||||||||||||||||||||||||
Recommendation
This test should be ordered and interpreted with results of a serum osmolality.
| Serum Osmolality* | Antidiuretic Hormone | SI Units (Conventional Units × 0.923) | |||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 270–280 mOsm/kg | Less than 1.5 pg/mL | Less than 1.4 pmol/L | |||||||||||||||||||||||||||||||||||||||
| 280–285 mOsm/kg | Less than 2.5 pg/mL | Less than 2.3 pmol/L | |||||||||||||||||||||||||||||||||||||||
| 285–290 mOsm/kg | 1–5 pg/mL | 0.9–4.6 pmol/L | |||||||||||||||||||||||||||||||||||||||
| 290–295 mOsm/kg | 2–7 pg/mL | 1.8–6.5 pmol/L | |||||||||||||||||||||||||||||||||||||||
| 295–300 mOsm/kg | 4–12 pg/mL | 3.7–11.1 pmol/L | |||||||||||||||||||||||||||||||||||||||
| *Conventional units. | |||||||||||||||||||||||||||||||||||||||||
Critical Findings and Potential Interventions
Effective treatment of the syndrome of inappropriate antidiuretic hormone production (SIADH) depends on identifying and resolving the cause of increased ADH production. Signs and symptoms of SIADH are the same as those for hyponatremia, including irritability, tremors, muscle spasms, convulsions, and neurological changes. The patient has enough sodium, but it is diluted in excess retained water. Failure to treat can be life threatening as water intoxication with sodium deficit leads to free water movement to cerebral cells, cerebral edema, coma, and death.
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