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Ordering Info & Methodology

Test Code

Cerner Synonyms


Methotrexate, mtx, TDM

Turn Around Time


Ordering Guide

Obtain last dose information. Test code includes dosage, time and date of last dose.

Specimen Requirements

Sample Type

Collection Container

Alternate Collection Containers



Dark Green (NO gel)

1.0 mL

Add on stability
This is the length of time after sample collection that this analyte is stable. Test can be added to a previously collected sample if the time since collection is less than the add on stability time.

Minimum Volume

Add On Stability

Collection and Shipping Requirements

Remove serum or plasma from cells within 1 hour of collection. Specimens must be sent same day as collection. If the afternoon BCCH courier is missed, batch samples and send by cab prior to the end of shift (1500 or 2300), 7 days a week.

Reference Intervals

Female Reference Interval

Age Category
Reference Interval

Male Reference Interval

Age Category
Reference Interval
Additional Notes

Measurement Uncertainty (MU)
Every laboratory value is an estimate of the true concentration of substance. MU is the 95% confidence interval around that estimate. 95% of the time, the true concentration will be within the range of the reported value ±MU. This value is based on analytical variability (precision) and does not reflect other factors such as sample collection and handling which may also affect the result.


Reported sodium = 140 mmol/L
Sodium MU = 1%
Expanded uncertainty = 140 mmol/L ± 1% or 140mmol/L ± 1.4 mmol/L
Interpretation - the true value of sodium in the sample is in the range 138.6-141.4 mmol/L, with 95% confidence.

Measurement Uncertainty

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