Sorted By Test Name - Mayo Medical Laboratories

TRICY
500509
bronchospasm) in infants and children less than 5 years due to food sensitivity (milk, egg, soy, and wheat
proteins) followed by respiratory disease (rhinitis and asthma) in older children and adults due to
sensitivity to inhalant allergens (dust mite, mold, and pollen inhalants).
Useful For: Testing for IgE antibodies may be useful to establish the diagnosis of an allergic disease
and to define the allergens responsible for eliciting signs and symptoms. Testing also may be useful to
identify allergens which may be responsible for allergic disease and/or anaphylactic episode, to confirm
sensitization to particular allergens prior to beginning immunotherapy, and to investigate the specificity of
allergic reactions to insect venom allergens, drugs, or chemical allergens.
Interpretation: Detection of IgE antibodies in serum (Class 1 or greater) indicates an increased
likelihood of allergic disease as opposed to other etiologies and defines the allergens that may be
responsible for eliciting signs and symptoms. The level of IgE antibodies in serum varies directly with the
concentration of IgE antibodies expressed as a class score or kU/L.
Reference Values:
Class IgE kU/L Interpretation
0 Negative
1 0.35-0.69 Equivocal
2 0.70-3.49 Positive
3 3.50-17.4 Positive
4 17.5-49.9 Strongly positive
5 50.0-99.9 Strongly positive
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management by
Laboratory Methods. 21st edition. Edited by RA McPherson, MR Pincus. New York, WB Saunders
Company, 2007, Chapter 53, Part VI, pp 961-971
Tricyclic Antidepressant Screen, Serum
Clinical Information: Amitriptyline Amitriptyline is a tricyclic antidepressant (TCA) that is
metabolized to nortriptyline, which has similar pharmacologic activity. The relative blood levels of
amitriptyline and nortriptyline are highly variable among patients. Amitriptyline is the drug of choice in
treatment of depression when the side effect of mild sedation is desirable. Nortriptyline is used when its
stimulatory side effect is considered to be of clinical advantage. Amitriptyline displays major cardiac
toxicity when the concentration of amitriptyline and nortriptyline 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. Nortriptyline Nortriptyline is unique among the antidepressants in that its blood
level exhibits the classical therapeutic window effect; blood concentrations above or below the therapeutic
window 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.
Nortriptyline is a TCA used for treatment of endogenous depression. It also is a metabolite of the
antidepressant amitriptyline. Nortriptyline is used when its stimulatory side effect is considered to be of
clinical advantage; amitriptyline is used when the side effect of mild sedation is desirable. 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. Imipramine Imipramine and its metabolite desipramine are
TCAs used to treat endogenous depression requiring 1 to 3 weeks of treatment before therapeutic
effectiveness becomes apparent. Desipramine is used for treatment of endogenous depression when the
patient needs a drug with significant stimulatory side effects. These drugs have also been employed in the
treatment of enuresis (involuntary urination) in childhood and severe obsessive-compulsive neurosis. The
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