Frequently Asked Questions

Frequently Asked Questions

1.  How long will it take to receive my results?

Complete amino acid analysis results are available within 10 working days.  Sample numbers larger than 60 may require additional time.

Taurine analysis results are available within 10 working days.

Samples such as food, body tissue, and other solids often require hydrolysis prior to analysis for amino acid composition.  Three additional working days are required if hydrolysis is necessary.

Mineral analysis takes 5 working days. 

2.  Should I send plasma or whole blood for taurine analysis? 

Although blood taurine concentration is only a fraction of the concentration in the tissues, blood and plasma taurine concentrations do change in proportion with tissue concentrations (Pacioretty L, Hickman MA, Morris JG, Rogers QR. Kinetics of taurine depletion and repletion in plasma, serum, whole blood and skeletal muscle in cats. Amino Acids 2001;21:417–427). Whole blood taurine concentrations may be used to substantiate a diagnosis of taurine deficiency when plasma concentrations are equivocal. In addition, whole blood taurine concentrations are only slightly altered after eating, whereas plasma taurine concentration may change substantially in taurine-depleted animals (Pion PD, Lewis J, Greene K, Rogers QR, Morris JG, Kittleson MD. Effect of meal-feeding and food deprivation on plasma and whole blood taurine concentrations in cats. J Nutr 1991;121:S177–S178.   Delaney SJ, Kass PH, Rogers QR, Fascetti AJ. Plasma and whole blood taurine in normal dogs varying size fed commercially prepared food.  J Anim Physiol Anim Nutr:  2003;87:236-244). 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.

In cases of taurine depletion, plasma concentrations decline into the critical range before whole blood concentrations reach the critical range.  However, in some cases where results are equivocal, or may be suspect due to sample hemolysis, measuring whole blood in addition to plasma or instead of plasma may yield a more reliable result. 

Our recommendation is to prepare both plasma and whole blood; submit one and retain the other in case the results are equivocal and analysis of the remaining sample is required to better determine taurine status. 

3.  Why don’t you analyze serum for taurine analysis?

Serum taurine concentrations are of questionable clinical value because of the variations in clotting times and methods of serum separation. In the experience of the Amino Acid Laboratory at the University of California, Davis the variability in serum taurine concentrations is greater than the variability in plasma taurine concentrations (Zicker SC, Rogers QR.  Use of plasma amino acid concentrations in the diagnosis of nutritional and metabolic diseases in veterinary medicine.  Proceedings IV Congress of the International Society for Animal Clinical Biochemistry 1990:1-15).

4.  Why do I need to deproteinize my sample with 6% sulfosalicylic acid (SSA) if I wish to get an accurate measure of methionine and cyst(e)ine?

The amino acid cysteine forms disulfide bonds with itself and with other sulfhydryl compounds in their free form and with sulfhydryls in protein. Protein-bound cysteine is lost when plasma proteins are removed before amino acid analysis. Remove plasma proteins within 1 hour after blood collection for reliable assay of free plasma cyst(e)ine. Please see the Torres et al. (2003) article on this web site for additional information.

5.   I see the web site reports normal ranges for dogs, cats and horses.  Do you run samples in other species, and if so, do you have normal ranges for them?

We do analyze for amino acids in other species.  Please call prior to sending any samples to see if we have normal ranges for the species you are interested in.