The influence of tocolytic therapy on serum digoxin-like immunoreactive substance concentration

Digoxin-like immunoreactive substance (DLIS) has been proposed to have a role in what seems to be the timely onset of labor. The relationship between the DLIS in patients with preterm labor and the success of tocolytic therapy with ritodrine and nifedipine has been studied. Using a commercially available radioimmunoassay kit, DLIS levels were determined in a total of 47 women with preterm labor and in 30 control. Tocolysis was successful in 37 of 47 women, in 20 of whom nifedipine and in 17 ritodrine was the tocolytic agent. Mean DLIS concentration was higher in patients with preterm labor. Moreover, DLIS levels were found to be decreased by successful tocolysis as could be observed from the values before initiation of tocolytic therapy and on the 3rd day of tocolysis for both nifedipine (0.268 +/- 0.198 vs. 0.220 +/- 0.210 ng/ml) and ritodrine (0.250 +/- 0.176 vs. 0.196 +/- 0.147 ng/ml; Wilcoxon test, p < 0.05).