Clonidine Suppression Test (One- to Three-hour)

Casandra

Casandra Test Code LC86527Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 123224CPT Code 82384

Clonidine Suppression Test (One- to Three-hour)

Also known as: Adrenaline, Plasma, Epinephrine, Plasma, Noradrenaline, Plasma, Norepinephrine, Plasma, Plasma Catecholamines

Clinical Use

Order Test

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.

Test Details

Methodology

Chromatography (High-pressure liquid chromatography (HPLC) with electrochemical detection)

Biomarkers

Catechol, Plasma, Total (Base)

Analyte

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Epinephrine, Plasma (Base)

Analyte

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Norepinephrine, Plasma (Base)

Analyte

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Result 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

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.