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

FLUOX
80228
increase bone density, they are used in dental preparations and as an antiosteoporotic agent. However,
prolonged high exposure to fluoride produces changes in bone morphology consistent with osteomalacia,
including prolonged mineralization lag time and increased osteoid thickness. The adverse skeletal effects
of fluoride are associated with plasma fluoride >4 mcmol/L. Chronic fluorosis may produce
osteosclerosis, periostitis, calcification of ligaments and tendons, and crippling deformities. Prolonged
exposure to the fluoride-containing antifungal agent voriconazole can produce high plasma fluoride
concentrations and bone changes (periostitis).
Useful For: Assessing accidental fluoride ingestion Monitoring patients receiving sodium fluoride
for bone disease or patients receiving voriconazole therapy
Interpretation: Humans exposed to fluoride-treated water typically have plasma fluoride in the
range of 1 to 4 mcmol/L. Those who are not drinking fluoride-treated water have plasma fluoride 4 mcmol/L indicate excessive exposure and are associated with
periostitis.
Reference Values:
0.0-4.0 mcmol/L
Clinical References: 1. Cardos VES, Whitford GH, Aoyama H, et al: Daily variations in human
plasma fluoride concentrations. J Fluorine Chem 2008:129;1193-1198 2. Wermers RA, Cooper K,
Razonable RR, et al: Long term use of voriconazole, a fluoride containing medication, is associated
with periostitis, fluorosis, and fluoride excess in transplant patients. Clin Infect Dis 2011;52:604-611
Fluoxetine, Serum
Clinical Information: Fluoxetine is a selective serotonin reuptake inhibitor approved for treatment
of bulimia, obsessive-compulsive behavior, panic, premenstrual dysphoria, and major depressive
disorder, with a variety of off-label uses. Both fluoxetine and its major metabolite, norfluoxetine, are
pharmacologically active, and are reported together in this assay. Most individuals respond optimally
when combined serum concentrations for both parent and metabolite are in the therapeutic range
(120-300 ng/mL) at steady state. Due to the long half-lives of parent and metabolite (1-6 days), it may
take several weeks for patients to reach steady-state concentrations. Fluoxetine is a potent inhibitor of
the metabolic enzyme CYP2D6, with lesser inhibitory effects on CYP2C19 and CYP3A. Therapy with
fluoxetine is therefore subject to numerous drug interactions, which is compounded by wide
interindividual variability in fluoxetine pharmacokinetics. Measurement of the drug is useful for
managing comedications, dose or formulation changes, and in assessing compliance. Side effects are
milder for fluoxetine than for older antidepressants such as the tricyclics. The most common side effects
of fluoxetine therapy include nausea, nervousness, anxiety, insomnia, and drowsiness. Anticholinergic
and cardiovascular side effects are markedly reduced compared to tricyclic antidepressants. Fatalities
from fluoxetine overdose are extremely rare.
Useful For: Monitoring serum concentration of fluoxetine during therapy Evaluating potential
toxicity Evaluating patient compliance
Interpretation: Most individuals display optimal response to fluoxetine when combined serum
levels of fluoxetine and norfluoxetine are between 120 and 300 ng/mL. Some individuals may respond
well outside of this range, or may display toxicity within the therapeutic range, thus interpretation
should include clinical evaluation. A toxic range has not been well established.
Reference Values:
Fluoxetine + norfluoxetine: 120-300 ng/mL
Clinical References: 1. Wille SM, Cooreman SG, Neels, HM, Lambert WE: Relevant issues in the
monitoring and toxicology of antidepressants. Crit Rev Clin Lab Sci 2008;45(1):25-89 2. Baumann P,
Hiemke C, Ulrich S, et al: The AGNP-TDM expert group consensus guidelines: therapeutic drug
monitoring in psychiatry. Pharmacopsychiatry 2004;37:243-265
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