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Test Code NTBC Orfadin Level

Important Note

Offsite:  Ship frozen plasma or serum

Clinical System Name

Orfadin Level


Tyrosinemia monitoring

Sample Requirements

Specimen: Whole blood

Container(s): Lt. Green/Lithium Microtainer, Dark Green/Sodium Heparin, Red, Gold SST

Preferred Vol: 1 mL

Minimum Vol: 0.5 mL




Processing Instructions

Reject due to:

Spin: Y

Aliquot: Y

Temp: - 20 C

Storage location: Transfer 0.5 mL plasma to plastic container. Freeze sample with copy of requisition in CPA Freezer, Fz3 rack.


Off-site collection: Transfer 0.5 mL plasma to plastic container.  Freeze plasma for storage and shipment.


Specimen Type Temperature Time
Plasma or serum Room temp 1 m
  Refrigerated 6 m
  Frozen 1 y



STAT Performed TAT
N Th 2-8 d


Performing Laboratory

Seattle Children's Laboratory    


Department:  Biochemical Genetics

Location: Biochemical Genetics

Phone Number: (206) 987-2617


Reference Range

Treatment should lead to normalized porphyrin metabolism; a general target for blood levels is 40-60 mcmol/L. Succinylacetone should not be detectable in urine or plasma. It may take up to three months before the level of plasma succinylacetone is normalized after the start of nitisinone treatment.


The half life of NTBC is 54 hrs. The time of blood collection with respect to drug dosage is not critical, however, one should strive for consistency for any one patient i.e. drug administration at night and blood collection the next morning. A trough level is not necessary.



Method: LC/MS/MS

Analytical Volume: 50 mcL plasma/serum


CPT Codes