Epinephrine
Overview
Epinephrine measures the catecholamine hormone and neurotransmitter secreted primarily by the adrenal medulla in response to stress, serving critical roles in the fight-or-flight response through stimulation of alpha and beta adrenergic receptors. It increases heart rate, cardiac output, bronchodilation, and blood glucose while redirecting circulation to vital organs. Elevated levels indicate pheochromocytoma, paraganglioma, stress, or certain drugs, while low levels may reflect adrenal insufficiency. Clinically, epinephrine measurement supports diagnosis of catecholamine-producing tumors when measured in plasma or urine.
Clinical Use Cases
- Diagnosis of pheochromocytoma and paraganglioma.
- Evaluation of neuroblastoma (as part of urine catecholamine metabolites).
- Assessment of autonomic dysfunction or orthostatic hypotension.
- Monitoring during critical care for catecholamine excess states.
Specimen Types
- Plasma (EDTA with or without reduced glutathione).
- 24-hour urine collection.
- Rarely, whole blood for point-of-care.
Measurement Methods
- High-performance liquid chromatography with electrochemical detection (HPLC-ECD).
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS).
- Immunoassays (less common due to cross-reactivity).
Test Preparation and Influencing Factors
- Avoid catecholamine-containing foods (bananas, vanilla, coffee, chocolate) for 48-72 hours.
- Discontinue interfering medications (levodopa, sympathomimetics, MAO inhibitors) if possible.
- Patient should rest supine 30 minutes pre-collection; acute stress elevates levels.
- Smoking, caffeine, and exercise within 24 hours increase results.
Synonyms
- Adrenaline.
- 1-(3,4-Dihydroxyphenyl)-2-methylaminoethanol.