Clonidine Suppression Test (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
Several medications can prevent clonidine suppression and should be discontinued 48 hours before collection if possible. These include β-adrenergic blockers, tricyclic antidepressants, and thiazide diuretics. α-adrenergic blocking agents do not interfere with clonidine suppression. The patient should abstain from smoking and avoid certain foods and medications prior to the test. An indwelling heparinized catheter is preferred to avoid stress-induced catecholamine elevation during venipuncture.
Limitations
Plasma levels are useful if elevated during or immediately following a hypertensive episode, but false-negatives can occur if the specimen is drawn during an uneventful period. Normotensive pheochromocytoma has been reported. False-positive results are common and can be influenced by various factors including certain drugs and extrinsic conditions such as cold or hypoglycemia.
Methodology
Chromosomal / Cytogenetics (HPLC with electrochemical detection)
Biomarkers
LOINC Codes
- 1464-7
- 1606-3
- 1388-8
- 1462-1
- 1604-8
- 16558-9
- 1463-9
- 1605-5
- 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, two-hour, and three-hour specimens
Minimum Volume
2.2 mL each for baseline, two-hour, and three-hour specimens
Container
Chilled lavender-top (EDTA) tube
Collection Instructions
Draw blood in chilled lavender-top (EDTA) tube. Invert tube for thorough mixing with preservatives. Centrifuge at 4°C. Transfer plasma to labeled plastic transport tubes and freeze immediately at -20°C. Ship frozen. Tubes should be prelabeled 'Baseline', 'Two-hour', 'Three-hour'. Separate frozen specimens for additional tests.
Patient Preparation
Abstain from smoking, walnuts, bananas, and certain medications. Use of an indwelling heparinized catheter is recommended. The patient should remain recumbent during the collection process.
Storage Instructions
Freeze
Causes for Rejection
Specimen not drawn in the correct tube, plasma not received frozen, thawed specimen, inadequate patient preparation