Clonidine Suppression Test (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

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.

Test Details

Methodology

Chromosomal / Cytogenetics (HPLC with electrochemical detection)

Biomarkers

Epinephrine

Analyte

Epinephrine, Plasma (Baseline, 2-hour, 3-hour)

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

Norepinephrine

Analyte

Norepinephrine, Plasma (Baseline, 2-hour, 3-hour)

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

Total Catecholamines

Analyte

Catecholamines, Plasma Total (Baseline, 2-hour, 3-hour)

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

LOINC Codes

Order Codes

1464-7 - Epineph pre 300 ug CLN PO Plas-mCnc
1606-3 - Norepineph pre 300 ug CLN PO Plas-mCnc
1388-8 - FCA Fract pre 300 ug CLN PO Plas-mCnc
1462-1 - Epineph 2h p 300 ug CLN PO Plas-mCnc
1604-8 - Norepineph 2h p 300 ug CLN PO Plas-mCnc
16558-9 - Catechols 2h p chal Plas-mCnc
1463-9 - Epineph 3h p 300 ug CLN PO Plas-mCnc
1605-5 - Norepineph 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, 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.