Tips, Tricks, and Frequently Asked Questions

Sample Preparation:

Can I send an EDTA tube?
We will run samples in EDTA, but the reference ranges we have established were done using lithium-heparin tubes. We do not expect much of a difference, but we do not currently have data that verifies this.
What size tubes and how much sample do you need?
We will accept any size lithium-heparin tube, please be aware, DO NOT overfill the small (micro) tubes. Tubes that are overfilled will clot easily and affect our ability to process the sample. If sending small tubes, we recommend sending several in case one breaks in transit. The minimum amount of total sample needed is 0.5 ml for any fluid sample (plasma, urine, whole blood). Ideally, send 1-2 ml if possible.
Can I use a lithium-heparin separator tube?
No! Please do not use a separator tube! Even if you do not spin the tube down, the gel/liquid that allows the separation of the red cells and plasma will interfere with processing the sample. This can negatively impact the results.
Can I use an expired tube?
No. Please use one that is not expired.
How long can samples stay in the fridge/freezer?
For taurine samples in the refrigerator the maximum we recommend is 1 week. For taurine samples in the freezer the maximum we recommend 2 months.
Do I need to submit a fasted sample?
No, the sample does not need to be from a fasted animal. When taurine status is adequate, there is little influence on timing of meals relative to sampling; however, in depleted animals the meal impact may be significant depending on the composition of the recent meal(s) relative to the longer-term diet. In cats, fasting can lower plasma concentrations artificially, but in healthy dogs, fasting does not have a significant impact.

Our current reference ranges were established based on blood collection 3 hours to 5 hours after a typical meal in animals eating a consistent diet. If the patient is a dog and has been on consistent diet (+/- consistent taurine supplementation), sampling time is not crucial. If the patient is a cat and you plan to have plasma tested, then sticking to the 3-5 hour post-meal sampling window is recommended.
The plasma was very hemolyzed after we spun down the sample, can I still send it?
No, we do not recommend sending a hemolyzed plasma sample. Hemolysis can falsely elevate the level of taurine detected in plasma since taurine is more concentrated in red blood cells. The most accurate plasma sample is straw-colored. We will still run hemolyzed samples, but if we receive a severely hemolyzed sample we will contact you and request a clean sample be sent.
Do you only run samples for cats and dogs?
We will run samples in other species as well, but be aware that in many cases we will not have reference ranges available. If you want to run samples on animals other than dogs, cats, or horses, please contact the lab to discuss your submission.
Do you run amino acid analysis on whole blood?
We do not recommend this as we do not have reference ranges for all amino acids in whole blood.
Do you run urine nitroprusside tests?
No.
Should I send plasma or whole blood for taurine analysis?
Although blood taurine concentration is only a fraction of the concentration in the tissues, whole blood and plasma taurine concentrations change in proportion with tissue concentrations in cats. Whole blood taurine concentrations may be used to substantiate a diagnosis of taurine deficiency when plasma concentrations are equivocal. A substantial increase in plasma or serum taurine concentration can occur secondary to taurine leakage from granulocytes and platelets, as occurs with clotting or hemolysis, but analysis of whole blood taurine concentration is not confounded by these effects.

Our recommendation is to prepare and submit both plasma and whole blood; simultaneously as this helps in cases where results are equivocal.
Do you analyze serum for taurine analysis?
We can analyze amino acids in serum; however, we do not have normal reference ranges for serum samples. In addition, serum taurine concentrations are of questionable clinical value because of the variations in clotting times and methods of serum separation. In our experience, the variability in serum taurine concentrations is greater than the variability in plasma taurine concentrations.

Shipping:

What shipping carrier can I use?
There is no preference, but be aware that USPS delivers to a central receiving facility on the university campus, so there is a delay before packages arrive to us. FedEx and UPS deliver directly to our building.
Why doesn’t the post office show your address?
USPS delivers to a central receiving facility on the university campus, and our specific address does not always come up in their automated system. Please hand-fill out the address label and the package should get to us.
Why does it take so long for you to get samples from the post office?
The central receiving facility on campus only delivers to our building Mondays, Wednesdays, and Fridays. The receiving facility knows to keep packages for us in the freezer, so rest assured your samples will still be accurate.
Do you provide discount shipping labels?
No, we do not provide any shipping labels at this time.

Results:

Can I as the owner receive the results?
Yes, but please include a note on the submission form that we need to send them to you. Also, please include your vet’s email on the form as we need to send the results to them as well.
Do you have a reference range for Goldens?
No, our laboratory does not have a specific reference range for Golden Retrievers at this time.
Are high taurine concentrations a problem?
There have been no reported risks associated with high blood taurine concentrations.

For Researchers:

Why do I need to deproteinize my plasma sample to get an accurate measure of cysteine?
The amino acid cysteine forms disulfide bonds with itself and with other sulfhydryl compounds in their free form and with sulfhydryl in protein. Protein-bound cysteine is lost when plasma proteins are removed before amino acid analysis. You will need to remove plasma proteins within 1 hour after blood collection for reliable assay of free plasma cysteine. Please see the Torres et al. (2003) article on this web site for additional information. It is not necessary to do this for urine samples.