Dopamine is a monoamine neurotransmitter that belongs to the catecholamine family; the catecholamine family includes dopamine, norepinephrine, and epinephrine. Dopamine is mainly produced in the nervous system and adrenal medulla; it plays a role in many brain functions like behavior and cognition.
The plasma reference ranges for dopamine are as follows  :
Supine adults - < 10 ng/ml (conventional units); < 0.065 nmol/L (SI units)
Ambulatory adults - < 20 ng/mL (conventional units); < 0.13 nmol/L (SI units)
Age 3-15 years - < 60 pg/mL (conventional units); < 0.39 nmol/L (SI units)
Table. Urine Reference Ranges (Open Table in a new window)
|Age||Conventional Units||SI Units|
|3-8 y||80-378 µg/24 h||523-2472 nmol/24 h|
|9-12 y||51-474 µg/24 h||334-3100 nmol/24 h|
|13-17 y||51-645 µg/24 h||334-4218 nmol/24 h|
|>17 y||52-480 µg/24 h||340-3139 nmol/24 h|
Catecholamines including dopamine may be elevated in the following instances:
After a medication withdrawal (eg, clonidine, alcohol)
In acute illness
With medications such as tricyclic antidepressants, buspirone, antipsychotic agents, cocaine, Levodopa, amphetamines, ephedrine, pseudoephedrine 
Collection and Panels
Patient instructions are as follows:
The patient should fast for at least 4 hours and should avoid smoking and caffeinated beverages.
Medication that interfere with catecholamines metabolism should be avoided if possible.
Specimen collection instructions are as follows:
An indwelling intravenous catheter should be used.
After catheter insertion, the patient should rest for 30 minutes in the supine position.
Withdraw the blood specimen afterward.
Collection tube - Lavender-top tube or green-top tube
Specimen preparation - Separate plasma from cells and transfer to transport tube in less than 1 hour and freeze immediately.
Storage/transport temperature - Frozen
Stability - Frozen (14 days)
Unacceptable conditions - Grossly hemolyzed specimens
Panels - Plasma fractionated catecholamines that include plasma dopamine, epinephrine, and norepinephrine
Patient instructions are as follows:
Medication that interfere with catecholamines metabolism should be stopped at least a week prior to the urine collection if possible.
Specimen collection - 24-hour urine collection, creatinine measurement on the same urine sample to assess the specimen adequacy
Collection container - Urine container with 25 mL 6N HCl preservative.
Specimen preparation: Separate plasma from cells and transfer to transport tube in less than 1 hour and freeze immediately.
Storage/transport temperature: Refrigerate during and after collection.
Stability - Room temperature: 3 days, refrigerated: 14 days, frozen: 14 days
Unacceptable conditions - A container with pH greater than 5
Panels - Catecholamines fractionation (free), 24-hour urine including urine dopamine, epinephrine, and norepinephrine
Dopamine is a monoamine neurotransmitter that belongs to the catecholamine family; the catecholamine family includes dopamine, norepinephrine, and epinephrine. Dopamine is mainly produced in the nervous system and adrenal medulla; it plays a role in many brain functions like behavior and cognition. [3, 4]
Tyrosine hydroxylase converts tyrosine to 3,4-dihydroxyphenylalanine (DOPA), which is converted to dopamine under the effect of aromatic l-amino acid decarboxylase, then dopamine β-hydroxylase converts dopamine to norepinephrine and phenylethanolamine N -methyltransferase converts norepinephrine to epinephrine. 
Plasma and/or urine dopamine tests are indicated as part of the work up for the diagnosis of the following conditions:
Plasma and/or urine dopamine can be used in the monitoring of the following conditions:
Neuroblastoma after therapy
Plasma fractionated catecholamines includes plasma dopamine, epinephrine, and norepinephrine, whereas 24-hour urine fractionated catecholamine includes urine dopamine, epinephrine, and norepinephrine.
In cases of pheochromocytoma, adrenal incidentaloma, and paraganglioma, plasma and urine dopamine must not be measured separately; rather, plasma fractionated catecholamines and 24-hour urine fractionated catecholamine should be ordered since rarely will pheochromocytomas and paragangliomas only secrete dopamine.
The most acceptable approach for pheochromocytoma diagnosis is to screen with 24-hour urine collection for fractionated metanephrines and catecholamines; if high clinical suspicion exists, then plasma fractionated metanephrines should then follow as a confirmatory test.
During the work-up for neuroblastoma, dopamine, whether in the urine or the plasma, should be measured in combination with 24-hour urine vanillylmandelic acid (VMA) and homovanillic acid (HVA).