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

Not provided.

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

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

Epinephrine, Plasma (Base)

Analyte

Concentration / Level

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

Norepinephrine, Plasma (Base)

Analyte

Concentration / Level

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

LOINC Codes

Result Codes

1606-3 - Norepineph pre 300 ug CLN PO Plas-mCnc
1464-7 - Epineph pre 300 ug CLN PO Plas-mCnc
1388-8 - FCA Fract pre 300 ug CLN PO Plas-mCnc
1603-0 - Norepineph 1h p 300 ug CLN PO Plas-mCnc
1461-3 - Epineph 1h p 300 ug CLN PO Plas-mCnc
1385-4 - FCA Fract 1h p 300 ug CLN PO Plas-mCnc
1604-8 - Norepineph 2h p 300 ug CLN PO Plas-mCnc
1462-1 - Epineph 2h p 300 ug CLN PO Plas-mCnc
16558-9 - Catechols 2h p chal Plas-mCnc
1605-5 - Norepineph 3h p 300 ug CLN PO Plas-mCnc
1463-9 - Epineph 3h p 300 ug CLN PO Plas-mCnc
16559-7 - Catechols 3h p chal Plas-mCnc

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.