CYP27A1 and hydrops fetalis: We have previously described increased serum levels of osteocalcin and β‐CTx in HF patients indicating high bone turnover.32 Another study showed a strong elevation of bone resorption markers in HF patients that correlated negatively with LV ejection fraction.44 Zotos et al. have shown that β‐CTx is correlated with the severity of HF and with the decrease in BMD.50 These bone markers, which accurately reflect early changes in bone metabolism, can be used to predict future bone loss.