A vasopressin level test measures the blood concentration of vasopressin (antidiuretic hormone) to evaluate water balance and fluid disorders. It helps diagnose conditions like diabetes insipidus, SIADH, unexplained hyponatremia, or circulatory shock. Blood is drawn for direct vasopressin or its stable surrogate, copeptin. Results guide diagnosis and treatment of abnormal urine output, sodium levels, or blood pressure.

A serum ADH (antidiuretic hormone) level test measures the amount of vasopressin in the blood to evaluate the body’s water balance. It helps investigate abnormal sodium levels, excessive urination or thirst, and conditions like SIADH or diabetes insipidus. Samples need prompt handling because ADH fluctuates; results are interpreted alongside clinical signs and other tests such as serum sodium and urine osmolality.

High vasopressin increases kidney water reabsorption, producing concentrated urine and reduced urine output, which raises blood volume and can elevate blood pressure. Excess levels cause dilutional hyponatremia, leading to nausea, headache, confusion, seizures or even coma in severe cases. Laboratory findings include low plasma osmolality with inappropriately high urine osmolality, as seen in SIADH.

ADH (antidiuretic hormone/vasopressin) blood test costs vary by country and provider. In the US, expect roughly $50–300 out‑of‑pocket; in the UK it’s usually free on the NHS when clinically ordered, private labs charge about £40–150. In India prices range about ₹400–2,000. Final cost depends on the lab, location, and whether insurance covers testing—check with your provider.

Vasopressin deficiency (central diabetes insipidus) causes large volumes of very dilute urine (polyuria), intense thirst (polydipsia) and frequent nighttime urination (nocturia). Other signs include dehydration with dry mouth and skin, lightheadedness, weakness and fatigue. Severe cases may develop hypernatremia leading to confusion, irritability, headache or seizures.

The blood test that checks ADH is a plasma antidiuretic hormone (ADH) or plasma vasopressin level. It’s typically measured with plasma and urine osmolality and sodium to assess conditions like SIADH or diabetes insipidus. ADH is labile, so samples need special collection (chilled EDTA tube, rapid processing) and results are interpreted in the clinical context.