White cell cystine
Used in the monitoring and diagnosis of cystinosis. Heterozygotes are phenotypically normal. Homozygotes usually present around 1-2 years old with polyuria, polydypsia, failure to thrive, rickets and Fanconi syndrome (generalised aminoaciduria with phoshaturia and glycosuria). They are treated with Cystagon which reduces lysosomal cystine accumulation and thereby preserves renal function.
|Tube||Heparin (no gel preferred)|
|Additional Information||Please note Cystinosis is NOT the same disease as cystinuria (a cause of renal stones).|
|Turn Around||28 days|
|Send to||Specialist Laboratory Medicine
St James hospital
|Collection Con||Minimum volume: 3 mL
Instructions for lab: Do not separate. Store whole blood at room temperature. Must arrive at Block 46 SJUH within 24 hours of venepuncture to allow white cell preparation (takes 2.5 hours, not available at weekends).
Please discuss with Biochemical Genetics lab prior to rejecting any samples.
|Sample REQ||Whole blood. Sample must be well mixed at venepuncture to prevent clots and received within 24 hrs of collection between Mon 9am to Fri 2pm. For monitoring a trough sample should be taken.|
|Ref. Range Notes||Normal: up to 0.5.
Heterozygotes: up to 1.0.
Cystinosis patients: usually greater than 2.0.
|Units||nmol ½ cystine per mg protein|
|Telepath||White cell cystine: CYSW1J|
|ICE Codes||White cell cystine: JCYSW|