UCSD Cystine Determination Laboratory


Therapeutic response to CystagonTM by cystinosis patients may be evaluated three to four times per year by the analysis of white blood cells. (see white blood cell procedure )

The physician or laboratory may request a white blood cell preparation kit. The kit contains solutions and protocol for the preparation of acid-stabilized white blood cells from 5 ml of patient's heparinized blood. The white cell sample is frozen and shipped to the Cystine Determination Laboratory for analysis.

Intracellular cystine level is determined by our laboratory, evaluated by Dr. Bruce Barshop and/or Dr. Jerry Schneider, and reported to the requesting physician.

If an insurer requires a letter of justification or statement of medical necessity for leukocyte (WBC or white blood cell) cystine assays in the diagnosis and treatment of cystinosis, we have provided boilerplate text to assist you.

Reminder: Blood must be taken 5-6 hours after a dose of CystagonTM and processed immediately for the white cell cystine measurements to be meaningful.

White Blood Cell Procedure

Request for White Blood Cell Preparation Kit

Contact the Cystine Determination Lab (see contact information here) to request information on how to prepare the sample. The Cystine Lab will provide solutions and instructions on the proper preparation of white blood cells from 5 ml heparinized whole blood drawn in the donor laboratory. Although, these materials can be shipped for arrival the next day, a weeks notice is preferred. The donor lab should have available a refrigerated centrifuge, micropipets, vortex mixer, wet ice and dry ice, and technical staff willing to spend 2 hours on the preparation. For diagnostic samples, a normal control is required.

Cystinosis Central Cystine Determination Lab Description of Tests & Services WBC Procedure