Specialized Collections   Grey Top Tubes (Sodium Fluoride) This tube stabilizes the specimen’s glucose component during transport. It must be at least 50% filled or the high concentration of sodium fluoride will interfere with glucose testing methods. The preferred method to stabilize a specimen for glucose and other chemistry assays is to collect a serum separator tube (SST), and centrifuge it after it clots to separate the serum from the blood cells. Alternately, draw a plain red top tube (RTT), centrifuge it, and transfer the serum to another RTT.   Therapeutics Drugs such as digoxin and phenobarbitol are most stable in blood samples drawn into a RTT, as the silicone gel of SST will absorb many drugs. Vitamin B12 and folate levels also may be affected by the SST gel, although elemental therapies such as bromides do not appear to be altered.   Blood Culture Specimens for blood culture require collection into a specialized vacuum culture bottle containing growth medium. The venipuncture site should be shaved, scrubbed clean with soap and water, and disinfected twice with an iodine preparation. Allow the site to dry. The rubber stopper of the culture bottle should be disinfected with alcohol. Obtain 1-3 mL blood using a needle and syringe, and transfer immediately into the culture bottle. Multiple blood cultures increase the chance of detecting bacteremia. Draw 2-4 bottles taken 1-2 hrs. apart with the animal off all antibiotics for at least 2 days. Leave culture bottles at room temp during transport.   Coagulation Testing Blood samples for coagulation testing must be drawn into a blue top tube (BTT). The BTT should be filled to at least 75%, but preferably 90% or more capacity, as results will be affected by excess citrate anticoagulant. Centrifugation and separation of plasma from cells is preferred if transportation to the laboratory takes more than 12 hours. Use a plastic pipette or small syringe to transfer the plasma to a clean plastic tube. Cap the plasma tube and keep cold or freeze at -20°C or lower. Freezing the plasma is not necessary unless testing will be delayed for more than 24 hours, but it should always stay cold. Repeated freezing and thawing of plasma denatures coagulation proteins. The Antech drivers have coolers to transport local samples. Samples being mailed should be shipped overnight with frozen cold packs. Plasma von Willebrand factor can be measured in samples collected in either BTT (preferred) or lavender top tube (LTT), following the guidelines above.   Urine Collection A RTT is the preferred collection tube for urinalysis and urine culture. A Copan swab can also be used for urine culture, but it precludes quantitation of results. Urine for culture is best collected by cystocentesis and transported with a cold pack to prevent bacterial overgrowth.   Endogenous ACTH Aprotonin (protease inhibitor) is added to a LTT to stabilize ACTH so freezing the sample is not needed. [Tubes are available from Antech.] The treated plasma should be separated immediately by centrifugation, transferred to a plastic tube, capped and refrigerated. Transport sample to the lab with cold packs.       Please send comments to the webmaster. ©1997-2008 Antech Diagnostics, Inc. Site design and maintenance by amesDesign.