Meconium nicotine and metabolites by liquid chromatography-tandem mass spectrometry: differentiation of passive and nonexposure and correlation with neonatal outcome measures.
BACKGROUND
Meconium analysis is a diagnostically sensitive and objective alternative to maternal self-report for detecting prenatal tobacco exposure. Nicotine and metabolite disposition in meconium is poorly characterized, and correlation of analytes' concentrations with neonatal outcomes is unexplored. Our objectives were to quantify nicotine, cotinine, trans-3'-hydroxycotinine (OH-cotinine), nornicotine, norcotinine, and glucuronide concentrations in meconium, identify the best biomarkers of in utero tobacco exposure, compare meconium concentrations of tobacco-exposed and nonexposed neonates, and investigate concentration-outcome relationships.


METHODS
We quantified concentrations of nicotine and 4 metabolites with and without hydrolysis simultaneously in meconium from tobacco-exposed and nonexposed neonates by liquid chromatography-tandem mass spectrometry. We compared meconium concentrations to birth weight, length, head circumference, gestational age, and 1- and 5-min Apgar scores.


RESULTS
Nicotine, cotinine, and OH-cotinine were the most prevalent and abundant meconium tobacco biomarkers and were found in higher concentrations in tobacco-exposed neonates. Whereas cotinine and OH-cotinine are glucuronide bound, performing the lengthy and costly enzymatic hydrolysis identified only 1 additional positive specimen. Unconjugated nicotine, cotinine, or OH-cotinine meconium concentration >10 ng/g most accurately discriminated active from passive and nonexposed neonates. There was no significant correlation between quantitative nicotine and metabolite meconium results and neonatal outcomes, although presence of a nicotine biomarker predicted decreased head circumference.


CONCLUSIONS
Unconjugated nicotine, cotinine, and OH-cotinine should be analyzed in meconium to detect in utero tobacco exposure, as approximately 25% of positive specimens did not contain cotinine. Immunoassay testing monitoring cotinine only would underestimate the prevalence of prenatal tobacco exposure.
Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Baltimore, MD 21224, USA.
Teresa R
TR
Gray
Raquel
R
Magri
Diaa M
DM
Shakleya
Marilyn A
MA
Huestis
D001034:Apgar Score; D015415:Biomarkers / Q000032:analysis; D049628:Body Size; D002853:Chromatography, Liquid; D003367:Cotinine / Q000031:analogs & derivatives / Q000032:analysis; D005260:Female; D005865:Gestational Age; D005965:Glucuronates / Q000032:analysis; D006801:Humans; D006868:Hydrolysis; D007231:Infant, Newborn; D018811:Maternal Exposure / Q000009:adverse effects*; D008431:Maternal-Fetal Exchange; D008470:Meconium / Q000737:chemistry*; D009538:Nicotine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000032:analysis* / Q000378:metabolism; D011247:Pregnancy; D012907:Smoking / Q000009:adverse effects*; D053719:Tandem Mass Spectrometry; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D015415:Biomarkers; D005965:Glucuronates; D014028:Tobacco Smoke Pollution; C085795:nicotine N-glucuronide; C066333:norcotinine; C001381:hydroxycotinine; D009538:Nicotine; C005311:nornicotine; D003367:Cotinine