The association between iron metabolism with the change of blood pressure and risk of hypertension: A large cross-sectional study

Background: The relationship between iron metabolism and variations in blood pressure and hypertension risk is still not clear. This study aimed to determine whether iron metabolism is associated with changes in blood pressure and hypertension prevalence in the general United States population. Methods: The National Health and Nutrition Examination Survey (NAHNES) database contains data on 116876 Americans from 1999 to 2020 years. Data from the NHANES database were used to examine the relationships between iron metabolism (serum iron [SI], serum ferritin [SF], and soluble transferrin receptor [sTfR]) and changes in blood pressure and hypertension prevalence. Generalized linear models and restricted cubic spline (RCS) plot curves were used to estimate the relationship between iron metabolism and hypertension. Further, generalized additive models with smooth functions were used to identify the relationship between iron meta-bolism and blood pressure. Finally, a stratified subgroup analysis was performed. Results: A total of 6710 participants were included in our analysis. The RCS plot showed a linear relationship between SI, as well as sTfR, and hypertension prevalence. SF and hypertension prevalence were associated in a J -shape. In addition, the relationship between SI and systolic blood pressure (SBP) and diastolic blood pressure (DBP) decreased initially and then increased. A correlation between SF, SBP, and DBP first decreased, then increased, and finally decreased. A positive linear correlation existed between sTfR and SBP, but it increased and then decreased with DBP. Conclusion: The correlation between SF and hypertension prevalence displayed a J-curve. In contrast, the cor-relation between SI, as well as sTfR, and hypertension risk was negative and positive, respectively.