Specimen

Plasma or CSF

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 ml whole blood in light green lithium heparin tube or one light green 
microtube or CSF.

Delivery Instructions:

Deliver to laboratory immediately after collection.

Testing Schedule:

0700-1630 Monday through Friday.
0600-1400 Saturday, Sunday and holidays.
Sample must be received by 1200 for same
day service.  For additional services,
contact Clinical Pathology Resident on-call
at #3404.

Analytic Time:

3 hours (upon receipt in laboratory)

Reference Range:

Clinical toxicity more frequent with serum concentrations:
>10 Exp-5 molar at 24 hrs. post infusion
>10 Exp-6 molar at 48 hrs. post infusion
>10 Exp-7 molar at 72 hrs. post infusion

Test
Limitations:

Specimens from patients who have received preparations of mouse 
monoclonal antibodies for diagnosis or therapy may contain human 
anti-mouse antibodies (HAMA).  HAMA present in serum may interfere in 
immunoassays which utilize mouse monoclonal antibodies.  These 
specimens should not be assayed with the TDx/TDxFLx Methotrexate II 
assay.

Methodology:

FPIA (Fluorescent Polarization ImmunoAssay)

CPT Code:

83520

See Additional Information:
Chemistry Critical Lab Values
Specimens Requiring Immediate Delivery