Fig. 3From: Evaluating urinary estrogen and progesterone metabolites using dried filter paper samples and gas chromatography with tandem mass spectrometry (GC–MS/MS)Interclass correlations of 24-h urine collections for β-pregnanediol (a), estradiol (b), versus the 4-spot assay. Correlation coefficients reported are Spearman correlations. Cr, creatinine; βPg, 5β-pregnanediolBack to article page