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A B C D E F G H I J K L M N O P Q

Test Identifier Information

 
Registration CodeCATP
Method

Extraction plus HPLC-EC

Diagnostic Use / Indications

NOTE: THIS IS NOT A STANDARD TEST FOR PHAEOCHROMOCYTOMA

The measurement of plasma catecholamines lacks both sensitivity (84%) and specificity (81%) for the diagnosis of Phaeochromocytoma. Accumulating evidence suggests that measurements of plasma free metanephrines or urinary fractionated metanephrines (normetanephrine and metanephrines separately) are the most sensitive tests for the diagnosis of Phaeochromocytoma. Plasma metanephrines have a high sensitivity (99%), but lack specificity (89%). Therefore the suggested approach to diagnosis is to screen with 24 hour urinary fractionated metanephrines and catecholamines. Plasma metanephrines are useful in equivocal cases and particularly in syndromic forms of phaeo (MEN2 and Von Hippel Lindau) where elevation in plasma metanephrines may precede any other biochemical abnormality.

Plasma catecholamines will be performed only after prior consultation with the laboratory. Contact the on-call chemical pathologist via switchboard or core laboratory after hours. Unless there has been prior consultation plasma metanephrines will be performed instead of catecholamines.

External PriceContact Canterbury Health Laboratories on +64 3 364 0484 or email Labinfo.
  

Specimen Collection

 
Pre-Testing Requirements

Since many factors alter plasma catecholamine levels, patient preparation is important. Avoid smoking and caffeine intake 12 hours before blood sampling. Ideally the patient should fast overnight prior to venous sampling in the morning.

Insert a venous line (butterfly is satisfactory), and flush with a heparin-saline solution (10 U/ml), and occlude.

When the line for blood drawing is secured, the patient is left recumbent in non-stimulating surroundings for 30 minutes.

At 30 minutes, clear the venous line then withdraw the sample (Supine) of 5ml blood for catecholamine measurement.

Note: Blood samples taken during or soon after a hypertensive crisis (or similar suspicious event) may be helpful for diagnosis of phaeochromocytoma.

Specimen Collection Protocols

2.1ml plasma preferred; however absolute minimum volumes for a non-repeatable result are:

Adrenaline & Noradrenaline = 1.1ml

Noradrenaline only = 0.2ml

Take blood into a 5ml vacutainer tube containing EDTA anticoagulant, which should be chilled in crushed ice & water prior to blood sampling.

Invert the tube several times to mix blood with anticoagulant. DO NOT SHAKE.

Immediately place the tube in an ice & water bath.

Centrifuge at +4ºC within 15 minutes of collection. Aspirate the plasma taking care to avoid the buffy coat of cells at the interface (platelets contain high levels of catecholamines).

Store and transport the plasma frozen (ideally at –80ºC).

Patient Specimen5 mL EDTA(Lavender) blood, see Reference.
Paediatric SpecimenSee minimum aliquot below
Sample Delivery to LabSeparated and frozen immediately
  

Instructions for Referral to CHLabs

 
Aliquot InstructionsMinimum 1.1 mL EDTA plasma, preferably >2mL, see Reference. Store at -80C.
Aliquot Transport to CHLDeep frozen (must be for cats only, no share samples)
  

CHLabs Laboratory

 
DepartmentEndocrinology Laboratory
Contact Details Email Email
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Contact Phone Number(03) 3640886 | x80886
Test AvailabilityMonthly
Turnaround TimeUp to 30 days
Reference Interval

Adrenaline <570pmol/L

Noradrenaline 470-3800pmol/L

Dopamine (when requested) <510pmol/L

Interpretation

Many medications alter circulating catecholamines therefore PLEASE NOTE DRUG THERAPY on the request form to assist interpretation of the result.

Most phaeochromocytoma cases will exhibit plasma catecholamine levels at least several-fold normal.

Borderline or modest elevation can reflect anxiety or other stimuli, including volume depletion, sepsis, posttrauma response etc. Modest elevations should be interpreted with great caution and if the clinical picture remains suggestive repeat sampling plus or minus a clonidine suppression test should be considered.

Uncertainty of Measurement

Adrenaline

+/- 100 pmol/L for <565.6 pmol/L

+/- 17.7% for >565.6 pmol/L

Noradrenaline

+/- 100 pmolL for < 1099 pmol/L

+/- 9.1% for >1099 pmol/L

Delphic Number Test Number6540

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