Test only available at LabPLUS (outside Christchurch send samples direct to Auckland). ONLY for patients suspected of having cystinosis.
This test is used for the diagnosis and monitoring of cystinosis.
Cystinosis is a rare disorder of lysosomal cystine transportation. It results in kidney, eye, thyroid and muscle disease. It usually presents in early childhood with failure to thrive, rickets and polyuria/polydipsia (renal Fanconi syndrome). Diagnosis is the finding of a significantly elevated white cell cystine.
Treatment of cystinosis is with Cysteamine. This removes lysosomal cystine. The mean elimination half-life of Cystagon capsules is approximately 1.5 hours. It is recommended that the leukocyte cystine levels should be measured 5 to 6 hours after Cystagon administration, with the goal of maintaining the levels < 1 nmol of half-cystine/mg protein.
Specialist Biochemistry
WCCY
Leucocyte half cysteine
White cell half cysteine
6 weeks
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