Accelerated increase in ferritin levels during menopausal transition as a marker of metabolic health.

Despite ferritin's role in iron and metabolic health, its timing and pattern of change relative to other iron biomarkers during the menopausal transition remain unclear, as blood loss shifts alter iron metabolism. This retrospective study analyzed longitudinal changes in 1,885 women aged 31-56 undergoing natural menopause, with at least 3 years of follow-up, using linear mixed models relative to the final menstrual period (FMP), segmented into pre-FMP, around-FMP, and post-FMP periods. Serum iron, ferritin, and transferrin saturation increased over time, whereas total iron-binding capacity (TIBC) decreased. TIBC declined rapidly around FMP, while other iron measures increased sharply and plateaued post-FMP. Serum ferritin levels, however, continued to rise post-FMP, with its coefficient (Standard Error; SE) sharply increasing from 2.10 (0.34) to 20.27 (0.50) between pre-FMP and around-FMP segments and remaining high at 9.34 (0.40) post-FMP. High ferritin residuals (> 1 SD above the mean) from regression models predicting ferritin levels by transferrin saturation were associated with fatty liver and metabolic syndrome components. These findings suggest that serum ferritin levels increase steeply during the menopausal transition and continue to rise post-FMP, reflecting iron status and metabolic health.