Sorted By Test Name - Mayo Medical Laboratories

FMPHN
91636
RIT
80456
MEX
9245
FMGMT
91907
Methylphenidate (Ritalin), Urine-Forensic
Reference Values:
Reference Ranges have not been established for urine
specimens.
This specimen was handled by Medtox Laboratories as a
Forensic specimen under chain of custody protocol.
Test Performed By: Medtox Laboratories
402 W. County Road D
St. Paul, MN 55112
Methylphenidate, Serum
Reference Values:
Reference Range: 5.0-20.0 ng/mL
Test Performed By
Medtox Laboratories, Inc.
402 W. County Road D
St. Paul, MN 55112
Mexiletine, Serum
Clinical Information: Mexiletine is a class I B antiarrhythmic with electrophysiologic properties
similar to lidocaine and is useful in suppression of ventricular arrhythmias. The drug exhibits a high
degree of oral bioavailability, is approximately 60% protein bound, and undergoes renal clearance at a
rate of 10.3 mL/min/kg. Mexiletine has a volume of distribution of 9.5 L/kg at a half-life of 11 hours.
Myocardial infarction and uremia reduce the rate of clearance and increase the half-life of mexiletine,
requiring dosage adjustment guided by drug monitoring. Mexiletine toxicity occurs at concentrations >2.0
mcg/mL (trough value) and is characterized by symptoms of nausea, hypotension, sinus bradycardia,
paresthesia, seizures, intermittent left bundle branch block, and temporary asystole.
Useful For: Assessing achievement of optimal therapeutic concentrations Assessing potential toxicity
Interpretation: Optimal response to mexiletine occurs when the serum concentration is within the
range of 0.8 mcg/mL to 2.0 mcg/mL (trough value).
Reference Values:
Therapeutic concentration: 0.8-2.0 mcg/mL (trough value)
Toxic concentration: >2.0 mcg/mL (trough value)
Clinical References: Joseph SP, Holt DW: Electrophysiological properties of mexiletine assessed
with respect to plasma concentrations. Eur J Cardiol 1980; 11:115-121
MGMT (O(6)-Methylguanine-DNA Methyltransferase (MGMT)
Assay) Gene Methylation Assay
Clinical Information: MGMT (O(6)-methylguanine-DNA methyltransferase) is a DNA repair
enzyme that is involved in the repair of damage caused by a variety of DNA crosslinking compounds,
including alkylating agents. Increased methylation of the MGMT gene promoter region causes diminished
or silenced expression of the gene, making cells more sensitive to DNA damage. This relationship has
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