Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

AFC
80334
AMOBS
8325
correlate with poor clinical response. Thus, therapeutic monitoring to ensure that the blood level is
within the therapeutic window is critical to accomplish successful treatment with this drug. Like
amitriptyline, nortriptyline can cause major cardiac toxicity when the concentration is in excess of 300
ng/mL, characterized by QRS widening leading to ventricular tachycardia and asystole. In some
patients, toxicity may manifest at lower concentrations.
Useful For: Monitoring serum concentration during therapy Evaluating potential toxicity The test may
also be useful to evaluate patient compliance
Interpretation: Most individuals display optimal response to amitriptyline when combined serum
levels of amitriptyline and nortriptyline are between 80 and 200 ng/mL. Risk of toxicity is increased with
combined levels > or =300 ng/mL. Most individuals display optimal response to nortriptyline with serum
levels between 70 and 170 ng/mL. Risk of toxicity is increased with nortriptyline levels > or =300 ng/mL.
Some individuals may respond well outside of these ranges, or may display toxicity within the therapeutic
range, thus interpretation should include clinical evaluation. Therapeutic ranges are based on specimens
drawn at trough (ie, immediately before the next dose).
Reference Values:
AMITRIPTYLINE AND NORTRIPTYLINE
Total therapeutic concentration: 80-200 ng/mL
Total toxic concentration: > or =300 ng/mL
NORTRIPTYLINE ONLY
Therapeutic concentration: 70-170 ng/mL
Toxic concentration: > or =300 ng/mL
Note: Therapeutic ranges are for specimens drawn at trough (ie, immediately before next scheduled
dose). Levels may be elevated in non-trough specimens.
Clinical References: 1. Wille SM, Cooreman SG, Neels HM, Lambert WE: Relevant issues in the
monitoring and the toxicology of antidepressants. Crit Rev Clin Lab Sci 2008;45(1):25-89 2. Thanacoody
HK, Thomas SH: Antidepressant poisoning. Clin Med 2003;3(2):114-118 3. Baumann P, Hiemke C,
Ulrich S, et al: The AGNP-TDM expert group consensus guidelines: therapeutic drug monitoring in
psychiatry. Pharmacopsychiatry 2004;37(6):243-265
Amniotic Fluid Culture for Genetic Testing
Clinical Information: Fetal cells obtained by amniocentesis (amniocytes) are used for a wide range
of laboratory tests. Prior to testing, the cells may need to be cultured to obtain adequate numbers of
amniocytes.
Useful For: Producing amniocyte cultures that can be used for genetic analysis Once confluent flasks
are established, the amniocyte cultures are sent to other laboratories, either within Mayo Clinic or to
external sites, based on the specific testing requested.
Reference Values:
Not applicable
Clinical References: Barch MJ, Knutsen T, Spurbeck JL: In The AGT Cytogenetics Laboratory
Manual. 3rd edition, 1997
Amobarbital, Serum
Clinical Information: Amobarbital is an intermediate-acting barbiturate with hypnotic properties
used in short-term treatment of insomnia and to reduce anxiety and provide sedation preoperatively. (1, 2)
Amobarbital is administered by intravenous infusion or intramuscular injection. The duration of its
hypnotic effect is about 6 to 8 hours. The drug distributes throughout the body, with a volume of
distribution of 0.9 to 1.4 L/kg, and about 59% of a dose is bound to plasma proteins. Metabolism takes
place in the liver primarily via hepatic microsomal enzymes. Its half-life is about 15 to 40 hours (mean: 25
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