Clonidine Suppression Test (One- to Three-hour)
Also known as: Adrenaline, Plasma, Epinephrine, Plasma, Noradrenaline, Plasma, Norepinephrine, Plasma, Plasma Catecholamines
Use
Diagnose pheochromocytoma and those paragangliomas that may secrete epinephrine, norepinephrine, or both. Such tumors may cause paroxysmal or persistent hypertension. Investigation of hypertensive patients, especially younger individuals, particularly when hypertension is paroxysmal, suggesting pheochromocytoma.2
Special Instructions
Patients should abstain from smoking and avoid walnuts, bananas, and certain interfering medications for a week prior to specimen collection. An indwelling heparinized catheter is recommended, and the patient should remain recumbent during collection. Clonidine hydrochloride is administered to assess plasma catecholamines at specific time intervals.
Limitations
False-negative results may occur when specimens are drawn during an uneventful period. Normotensive pheochromocytoma can also cause false negatives. False-positive results are common and can be influenced by cold, hypoglycemia, and certain medications including adrenergic blockers and tricyclic antidepressants, which may pose interference with the Clonidine Suppression Test results.
Methodology
Chromatography (High-pressure liquid chromatography (HPLC) with electrochemical detection)
Biomarkers
LOINC Codes
- 1606-3
- 1464-7
- 1388-8
- 1603-0
- 1461-3
- 1385-4
- 1604-8
- 1462-1
- 16558-9
- 1605-5
- 1463-9
- 16559-7
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
3 mL each for baseline, one-hour, two-hour, and three-hour specimens
Minimum Volume
2.2 mL each for baseline, one-hour, two-hour, and three-hour specimens
Container
Chilled lavender-top (EDTA) tube
Collection Instructions
Draw blood in chilled lavender-top (EDTA) tube, invert to mix preservatives. Centrifuge at 4°C, transfer plasma to labeled plastic transport tubes, freeze immediately at -20°C, and ship frozen. Ensure tubes are prelabeled with 'Baseline', 'One-hour', 'Two-hour', and 'Three-hour'.
Patient Preparation
Avoid smoking, walnuts, bananas, and certain interfering medications. Use an indwelling heparinized catheter and remain recumbent. Collect baseline blood 30 minutes after catheter insertion, administer clonidine hydrochloride orally, then collect plasma samples at one-hour, two-hour, and three-hour intervals.
Storage Instructions
Freeze.
Causes for Rejection
Specimen not drawn in correct tube, plasma not received frozen, thawed specimen, inadequate patient preparation.