Association of elevated umbilical cord blood creatine kinase and myoglobin levels with the presence of cocaine metabolites in maternal urine.

STUDY OBJECTIVE: To determine whether an association exists between antenatal cocaine exposure and elevated levels of creatine kinase (CK) and myoglobin in umbilical cord blood collected upon delivery. STUDY POPULATION: 105 anonymous maternal urines with corresponding infant umbilical cords bloods. METHODS: Maternal urines were screened for cocaine metabolites by the Syva EMIT assay, with positive specimens confirmed by gas chromatography/mass spectrometry. For all 8 positives, plus the first 47 of the negatives collected, matched infant cord blood specimens were analyzed for myoglobin by radioimmunoassay and CK by kinetic enzyme activity assay. Cord bloods matched to the remaining 50 cocaine-negative urines were not analyzed. A two-tailed Mann-Whitney test was used to evaluate the significance of differences in CK and myoglobin levels between the two groups. RESULTS: CK levels were evaluated twofold in the cocaine-positive group as compared to the cocaine negative group (mean 383 +/- 260 vs. 189 +/- 68 IU/L, p = 0.005). Myoglobin levels were twofold higher in the cocaine-positive group compared to the cocaine negative group (mean 55.9 +/- 37.1 vs. 33.3 +/- 26.8 ng/mL, p = 0.077). CONCLUSION: Antenatal cocaine exposure is associated with elevated cord blood CK, and possibly with elevated cord blood myoglobin. Additional studies, using larger study populations and more sensitive methods of detecting antenatal cocaine exposure, along with detailed follow-up examination of infants, are indicated.

Effect of antibody specificity on results of selected digoxin immunoassays among various clinical groups.

We examined the specificity of three automated digoxin immunoassays (Abbott TDxFLx Digoxin II assay, Baxter-Dade Stratus II Digoxin assay, and Ciba Corning ACS Digoxin assay) applied without modification to (a) sera from 229 digoxin-free patients in 12 cohorts associated with nonspecific or endogenous digoxin-like immunoreactive factor (DLIF) interference, and (b) drug-free serum supplemented with the major metabolites and analogs of digoxin. We observed three patterns of apparent digoxin results among the DLIF samples: one common to kidney and liver failure patients, where TDx and Stratus assays showed significant positive results; one common to newborns and cord blood, where only the TDx assay had significant interference; and one from cardiac surgery patients, where the Stratus assay alone showed interference. Of the three assays, the ACS had the least interference from DLIF. The assays also behaved differently with respect to cross-reactivity with digoxin metabolites, digitoxin, and digitoxin metabolites. The ACS assay again had the least analog or metabolite cross-reactivity. The three methods agreed well on digoxin-positive specimens, with a mean bias of <0.15 microgram/L digoxin for each and discrepancies (defined as >3 SD between the assay pairs compared) of only 3-5%.

Clinical evaluation of the NBD-PC fluorescence polarization assay for prediction of fetal lung maturity.

OBJECTIVES: 1) To examine a fluorescence polarization (FP) assay with an independent set of data that contained more cases of respiratory distress syndrome (RDS) than a previous study, 2) to determine whether the same reference ranges are applicable to infants born to diabetic women, and 3) to evaluate whether adding the lecithin-sphingomyelin ratio (L/S) would substantially improve the prediction of RDS among women with an intermediate FP value (between 0.26-0.289). METHODS: We identified 389 women who had FP analysis performed at the University of Washington Medical Center from February 1986 to October 1988 and who delivered within 3 days of amniocentesis. We reviewed the medical records of these women and their infants to extract information for our study. RESULTS: For FP values of 0.26 or greater, the sensitivity and specificity for prediction of RDS were 90.2 and 84.6%, respectively, compared with 100 and 82.0% in the previous study. For FP values of 0.29 or greater, the sensitivity and specificity were 62.8 and 94.2%, respectively (80.8 and 96.2% in the previous study). Among diabetics, an FP result below 0.26 was associated with the same low risk of RDS as among non-diabetics. Among the patients with FP between 0.26-0.289, the addition of L/S did not provide a clinically useful improvement in the prediction of fetal lung maturity. CONCLUSION: The NBD-PC FP assay can be used as the sole test of fetal lung maturity in most clinical circumstances.