There is this 2017 study: The association of ferritin with cardiovascular and all-cause mortality in community-dwellers: The English longitudinal study of ageing - PMC
I’ll try to summarize it the best I can. If I missed anything important or have provided false information. Please correct me, I’m here to learn.
~5.300 men and women aged 50 years and older were participating.
Researchers made these quartiles:
The ranges that are in italics are the ranges that showed the lowest relative all cause and cardiovascular mortality (reference).
Male
Lowest ferritin (2-69 ng/ml)
2nd lowest (70-118 ng/ml)
Medium (119-193 ng/ml)
High (194-598 ng/ml)
Female
Lowest ferritin (2-44 ng/ml)
2nd lowest (45-73 ng/ml)
Medium (74-115 ng/ml)
High (116-341 ng/ml)
The covariates
“Age, marital status (married versus not), major self-reported doctor diagnosed diseases i.e. heart disease, stroke, cancer, chronic lung disease, and diabetes mellitus, educational attainment (measured using three levels ranging from no qualifications to A-levels or higher), and total net household wealth (divided into tertiles) were considered as potential confounders.”
First of all, there was no association with ferritin levels and all-cause mortality, in ALL men.
BUT!
For the subgroup of males that had no baseline chronic disease, the high range was associated with an increased risk of mortality independent of all covariates.
In men, there was a positive association between highest ferritin quartiles and the risk of cardiovascular mortality after adjustment for age, chronic diseases and anemia.
Adjustment for additional covariates (lifestyle, inflammation) attenuated this association and in this case men with ferritin levels belonging to the second lowest quartile showed significantly increased cardiovascular mortality than those in the reference category (i.e. ferritin quartile: 119-193ng/ml)
In women, those with low ferritin levels were at increased risk of all-cause mortality compared to women in the reference category irrespective of adjustment for covariates. This association persisted even after excluding major baseline chronic disease.
Quick recap, what do we know thus far?
Healthy males w/ high ferritin = increased risk of mortality. (Why not all males? Read discussion)
Males that have anemia, chronic disease and are old w/ ferritin in two highest quartiles = positive association with cardiovascular mortality.
Males that have anemia, chronic disease, are old, high hsCrp and bad lifestyle habits w/ 2nd lowest ferritin = increased risk of cardiovascular mortality compared to males in the reference range with the same covariates.
All Females w/ low ferritin = associated with increased risk of all-cause mortality.
Discussion
“Regarding all-cause mortality in men, we found a positive association with high ferritin quartiles, but only in the subgroup without any baseline major chronic disease. Because of this variation by chronic disease status, we hypothesized that the association between high ferritin levels and all-cause mortality in the general male population may be obscured by comorbidities.”
