Definition
- Antidiuretic hormone (ADH), also known as vasopressin or arginine vasopressin, is a hormone secreted by the posterior pituitary. It regulates the water permeability of renal collecting ducts and urine concentrating ability by increasing water reabsorption, which is mediated by transcellular water channels (aquaporins).
- Normal range: <1.5 pg/mL (see Table 16.9 for effect of plasma osmolality on ADH levels).
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TABLE 16 " “9Plasma Osmolality Influences on ADH LevelsView LargeTABLE 16 " “9Plasma Osmolality Influences on ADH Levels Values in mOsm/kg Values in pg/mL 270 " “280 <1.5 280 " “285 <2.5 285 " “290 1 " “5 290 " “295 2 " “7 295 " “300 4 " “12
Use
- Diagnosis and differential diagnosis of DI and psychogenic polyuria
- Diagnosis of SIADH
- Differential diagnosis of hyponatremias
Interpretation
Increased In
- Nephrogenic DI (partial or complete): high ADH and low osmolality
- Primary psychogenic polydipsia
- SIADH inappropriately increased for degree of plasma osmolality (i.e., normal ADH relative to osmolality)
- Ectopic ADH syndrome
- Certain drugs (e.g., chlorpropamide, phenothiazine, Tegretol)
Decreased In
- Central DI (partial or complete): decreased for level of plasma osmolality
- Psychogenic polydipsia
- Nephrotic syndrome
Limitations
- Higher secretion occurs at night; in erect posture; with pain, stress, or exercise; and with increased plasma osmolality.
- Lower secretion occurs in recumbency, hypoosmolality, volume expansion, and hypertension.
- Plasma sample should not be left at room temperature.