Hemoglobin concentration declines without alterations in SI, TIBC, TS, or sTfR after 12 wk of weight training. The SF level of males with adequate iron status is lowered with weight training but not among females or males with low iron status.

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Aim: To develop a liquid chromatography mass spectrometry (LCMS) method for blood spot 17-hydroxyprogesterone (17OHP) as a second tier newborn screening test for congenital adrenal hyperplasia (CAH). To determine whether the method will improve screening for CAH in New Zealand Method: The LCMS method was developed by eluting 17OHP from blood spots using 100% methanol with added deuterated internal standard. 17OHP was extracted by injection onto an inline solid phase extraction column before back-flushing with elution solvent onto an analytical column and separation from potentially interfering compounds before mass spectrometry detection. Results: Analysis of 17OHP on 148 samples from patients treated for CAH yielded a regression line y=0.76x + 4.79 and r 2 =0.81 when compared with the current method. The coefficient of variation (CV) was 25% (40-150 nmol/L). Recovery was 92-108% and the linearity up to 2000 nmol/L. Of 62 initially positive CAH screens, 21 remained elevated after measurement with immunoassay after solvent extraction. Analysis by LCMS resulted in 7 positive screens, thus reducing the false positive rate by 67%. Conclusions: Initial results demonstrate the potential for improved specificity for screening by adopting an LCMS assay for 17-OHP. Precision and accuracy improvements will require an instrument with higher sensitivity.