UCSD Cystine Determination Laboratory

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Therapeutic Monitoring: Monitoring Intracellular Cystine in White Blood Cells (WBC, Leukocytes)

We recommend that WBC cystine be measured just before a dose of cysteeamine, near the "trough" of cysteamine (the time of lowest drug level). As opposed to CystagonTM, the absolute trough comes a little later with ProcysbiTM, about a half hour after the dose, but the small difference in WBC cystine is less of a consideration than the practical concerns about precise timing after a dose, as larger differences could arise if sampling is delayed.

Diagnosis of Cystinosis

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