CRP and cystic fibrosis: Patients with CF have higher levels of CRP, IL-6, and TNF-α, as well as the bone turnover markers C-terminal telopeptide, bone alkaline phosphatase, and OPG in their forearm veins compared with HP and DP at initial measurement.41 This finding appears to contradict previous work, which showed that OPG levels are higher in both CF and DP relative to HP, without a significant difference between CF and DP.17 This discrepancy could possibly be explained by the higher sample size used by the Folestad group.