Specimen Collection and Handling

1. Draw blood in lavender-top (EDTA) tube or green-top (heparin) tube.

2. Invert to mix with preservatives.

3. Centrifuge and transfer the plasma to labeled plastic transport tube.

4. Freeze immediately (within one hour after collection) at -20°C and ship frozen. The time between blood collection and the preparation of plasma is quite critical; if the time exceeds one hour, catecholamine values increase (when blood is kept at 4°C) or decrease (when left at 20°C). To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Patient Preparation:

Patient should not be smoking for four to six hours. Walnuts, bananas, and α-methyldopa (Aldomet®) should be avoided for a week prior to sampling. Other drug interference may occur, including epinephrine and epinephrine-like drugs (eg, nosedrops, sinus and cough preparations, bronchodilators, appetite suppressants). Test is unreliable in subjects on levodopa or methenamine mandelate. Avoid patient stress. See Limitations. An indwelling heparinized venous catheter is advocated, since venipuncture can cause an increase in the substances for which testing is being done. Patient should remain supine in quiet surroundings for at least 30 minutes.