Precaution |
Guideline for Specimen
Collection
- Obtain acid-preserved urine containers (U3 bottles) for collection of 24 Hr urine. The containers should be stored in cool place during collection.
- Female patients should avoid urine collection during menstrual period.
- Patients on certain drugs may have potential physiological interferences with the test. Please refer to the List of Interfering Drugs for Catecholamines and Metanephrines for more details. Patient should NOT stop or change any prescribed drugs without prior approval from the attending doctors.
- Patients should avoid coffee, tea, bananas, chocolate, cocoa and vanilla for at least 24 hours before, and during specimen collection.
- Stress period like acute illness, malignant hypertension or recent myocardial infarction, and also vigorous or prolonged exercise prior to urine collection may increase the endogenous secretion of adrenaline affecting the results.
- At the beginning of the urine collection, empty the urinary bladder and discard this urine. This time represents the beginning of the 24 hour period (e.g. 08:30 a.m. on Day 1). Collect all urine passed over the next 24 hours and add the urine to the urine containers and mix. At the end of the 24 hour period (i.e. 08:30 a.m. on Day 2), empty the urinary bladder and add this sample to the urine containers.
- Record the date and time of commencement and completion of urine collection.
- Return the urine sample and request form together, as soon as possible after the completion of the collection.
List of Interfering Drugs for Catecholamines and Metanephrines
The drugs listed below may adversely affect the test results of catecholamines and metanephrines. If possible, discontinue these drugs for at least 1 week before and till the end of urine collection. (Source of reference: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6e, 2017)
|
Catecholamines |
Metanephrines |
NE |
EPI |
NMN |
MN |
Tricyclic Antidepressants |
Amitriptyline, imipramine, nortriptyline |
+++ |
↔ |
+++ |
↔ |
Alpha-Blocker (Nonselective) |
Phenoxybenzamine |
+++ |
↔ |
+++ |
↔ |
Alpha-Blockers (α1-selective) |
Doxazosin, terazosin, prazosin |
+ |
↔ |
↔ |
↔ |
Beta-Blockers |
Atenolol, metoprolol, propranolol, labetalol |
+ |
+ |
+ |
+ |
Calcium Channel Antagonists |
Nifedipine, amlodipine, diltiazem, verapamil |
+ |
+ |
↔ |
↔ |
Vasodilators |
Hydralazine, isosorbide, minoxidil |
+ |
↔ |
Unknown |
Monoamine Oxidase Inhibitors |
Phenelzine, tranylcypromine, selegiline |
↔ |
↔ |
+++ |
+++ |
Sympathomimetics |
Ephedrine, pseudoephedrine, amphetamines, albuterol |
++ |
++ |
++ |
++ |
Stimulants |
Caffeine (coffee, tea), nicotine (tobacco), theophylline |
++ |
++ |
Unknown |
Miscellaneous |
Levodopa, carbidopa |
++ |
↔ |
Unknown |
Cocaine |
++ |
++ |
Unknown |
+, Mild ↑ if any; ↔, little or no ↑; ++, moderate ↑; +++, substantial ↑
EPI, epinephrine; MN, metanephrine;
NE, norepinephrine; NMN,normetanephrine.
|
|
Reference interval |
Adult:
Noradrenaline |
Adrenaline |
Dopamine |
63 - 416 nmol/day |
19 - 113 nmol/day |
221 - 2,410 nmol/day |
(Source: J Chromatogr 1988;459:251-260)
Children (nmol/mmol creatinine):
Age |
Noradrenaline |
Adrenaline |
Dopamine |
0 - < 0.25 year |
< 140 |
< 26 |
< 1,150 |
0.25 - < 2 years |
< 120 |
< 26 |
< 1,350 |
2 - < 10 years |
< 60 |
< 15 |
< 650 |
10 - < 18 years |
< 40 |
< 10 |
< 480 |
(Source: established using samples from local population) |
Result interpretation |
Excretion of adrenaline and noradrenaline is usually increased in phaeochromocytoma, particularly after a hypertensive paroxysm.
Excretion may also be increased in malignant hypertension and with severe stress.
Interpretation of clonidine suppression
test for phaeochromocytoma:
Phaeochromocytoma is unlikely if:
-
Urine noradrenaline (nmol) / Urine Cr (mmol) ratio is < 40, based on local data; but < 60, based on Western data
-
Urine adrenaline (nmol) / Urine Cr (mmol) ratio is < 20
-
Diurnal rhythm of catecholamines production is maintained.
See also urine free metanephrines and vanillylmandelic acid (VMA). |