Specimen Collection

Recommendations for patient preparation, diet, drug control and collection procedures described in this Web site should be followed to ensure valid test results. In most cases, specimens should be collected after an overnight fast. An overnight (14h) fast is necessary or highly recommended for some tests - see a table of Tests Requiring Special Collection, Storage and Transportation Conditions.

Separate serum (or plasma) from clot (or cells) as soon as possible. Avoid hemolysis. Highly lipemic specimens may be cleared by ultracentrifugation. It may be advisable to immediately re-collect grossly hemolyzed or lipemic specimens.

Generally, specimens for therapeutic drug monitoring and compliance verification should be collected at trough (or lowest concentration) levels that occur just before the next drug dose is administered. Do not measure drugs levels for therapeutic monitoring until the body reaches a steady state drug concentration. Steady state drug levels are reached after regular dosage for a period equivalent to the clearance rate of 5 half lives (T1/2) for that drug. Specimens collected to investigate toxicity can be collected at peak concentration levels or any time toxic signs and symptoms appear.

Many tests require specimens to be frozen or maintained at ambient temperatures (15 - 20°C) during storage and transportation. A table of Tests Requiring Special Collection, Storage and Transportation Conditions is included.