Cystine, WBC (Referred Out) - Saskatoon
Discipline
Biochemistry
Overview
Description
- Collection only available on Tuesday 0800-1000 hours.
- Requesting Physician / nurse must call 306-655-2089 to pre-book the test at least 24 hours in advance to confirm with RUH Chemistry Supervisor or Technologist II that staff are available for requested booking date. RUH lab staff will complete Cystine Collection Booking Form with the physician/nurse requesting the booking.
- Clearly indicate if the request is for therapeutic drug monitoring or diagnostic testing.
- For diagnostic purpose, recommend to submit a normal whole blood specimen collected from a healthy individual. Please ask patient or patient’s parents to provide a normal whole blood control sample.
- Specimen should be collected just before a dose of cysteamine (near the “trough” cysteamine).
- For therapeutic monitoring, please indicate the time of last medication and the time of blood collected.
Preferred Specimen Collection
- RUH Selective Test Centre
Forms Required
- Requisitions must have specific test indicated
- Miscellaneous Specimen Requisition Form #101878 or SHR Laboratory Medicine Community Laboratory Requisition Form #101064 or Acute Care Phlebotomy Requisition Form #101062
- Metabolic Disease Laboratory Requisition (Referred-Out)
Alias
- Cystinosis
Specimen Information
Specimen types accepted
- Whole blood
Specimen collection container
- Preferred collection container: Dark Green (Lithium Heparin) 6.0mL
- Alternative collection container: Dark Green (Sodium Heparin) 4.0mL
Collection procedure
- Collect 6.0 mL whole blood
- Send to RUH Chemistry Lab at room temperature immediately after collection for WBC isolation.
- Specimen should not be held at room temperature longer than 60 minutes.
Required volume
- Optimal volume: 6.0 mL whole blood
- Minimum/Pediatric volume: 5.0 mL whole blood
Transport and stability
- WBC lysate stable for 2 weeks frozen
Rejection criteria
- Specimens received where the proper collection protocols were not followed.
- Pathology and Laboratory Medicine Acceptance and Rejection Criteria
Testing Information
Relevant clinical history
- Cystinosis; cysteamine therapy
Performance
Methodology
- Liquid chromatography-tandem mass spectrometry with a deuterium-labelled internal standard.
Days/times performed
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Maximum laboratory time
- 3 – 4 week turnaround time by referral laboratory
Other information
Additional comments
- Aids in the diagnosis and monitoring of cystinosis.
- The reference ranges for treated levels are based on published studies of patients where samples were drawn between 6 and 8 hours after the last cysteamine dosed.
- Proper interpretation of results in known cystinosis patients on treatment is dependent on the timing of the patient’s last dose.
Last Updated: October 11, 2024