Hepcidin extremes track with different risks in chronic kidney disease
In chronic kidney disease, iron regulation is never just about anemia. The CRIC investigators examined hepcidin, the central hormone that governs systemic iron handling, and found that both ends of the distribution carried clinical signal in a large cohort of patients with CKD. Higher plasma hepcidin aligned with worse kidney and vascular outcomes, while lower hepcidin marked greater all-cause and cardiovascular mortality in adjusted analyses.
The pattern was not uniform across every endpoint. Incident heart failure and new-onset prediabetes or diabetes did not move with hepcidin level, even though the biomarker tracked with a broad cluster of adverse metabolic and inflammatory features at baseline. The result points to a narrower but clinically important role for hepcidin in renal and atherosclerotic risk rather than a universal prediction of every cardiorenal complication.
A biomarker embedded in iron, inflammation, and kidney dysfunction
The cohort included 3,826 patients enrolled in the Chronic Renal Insufficiency Cohort study. Median plasma hepcidin was 43 ng/mL, with an interquartile range of 22 to 77 ng/mL, placing the biomarker squarely in a range that reflected substantial heterogeneity across participants. Higher hepcidin levels clustered with older age, male sex, non-Hispanic Black race, diabetes, lower estimated glomerular filtration rate, and higher albuminuria.
Those associations are biologically coherent. Hepcidin rises when inflammation and iron loading drive the liver to suppress ferroportin-mediated iron export, trapping iron within storage sites and limiting circulating availability. In CKD, that axis can become distorted by reduced renal clearance, chronic inflammation, altered iron therapy exposure, and advancing nephron loss. The biomarker therefore sits at the intersection of impaired filtration, inflammatory signaling, and iron trafficking, all of which are active in this population.
The hepcidin gradient also tracked with several other circulating markers. Higher levels were associated with increased plasma iron indices, higher C-terminal fibroblast growth factor 23, and inflammatory markers including high-sensitivity C-reactive protein and interleukin-6. Those correlations strengthen the interpretation that hepcidin is not an isolated laboratory curiosity in CKD; it reflects a broader biologic state that may shape long-term organ risk.
Kidney and atherosclerotic outcomes rose at the top end
Investigators estimated hazard ratios across hepcidin tertiles using Cox proportional hazards regression, with the primary kidney endpoint defined as end-stage kidney disease or a 50% decline in eGFR. Compared with the middle tertile, the highest hepcidin tertile was independently associated with increased risk for kidney outcomes, with a hazard ratio of 1.19 and a 95% confidence interval of 1.09 to 1.30.
A similar directional pattern emerged for atherosclerotic events. The highest hepcidin tertile carried a hazard ratio of 1.34 for these events, with a 95% confidence interval of 1.09 to 1.64, again using the middle tertile as the reference group. The signal persisted after multivariable adjustment, which included iron indices and inflammatory measures, making a simple explanation based only on systemic inflammation less convincing.
The kidney association fits with the physiology of advanced CKD. Hepcidin excess may mirror a state of chronic inflammatory iron sequestration, and the same biologic environment can accelerate vascular injury, endothelial dysfunction, and microvascular damage within the kidney itself. In a cohort already marked by reduced eGFR and albuminuria, hepcidin may be identifying a subgroup with more active, ongoing pathology rather than merely documenting altered iron stores.
Low hepcidin pointed in the opposite direction for mortality
The lower end of the hepcidin distribution told a different story. The lowest tertile was associated with increased risk for both all-cause mortality and cardiovascular mortality in fully adjusted models that included iron indices and inflammation. No hazard ratio was provided in the abstract, but the association remained after accounting for the major biologic correlates of the biomarker.
That inverse mortality signal makes interpretation more complex, and more clinically interesting. Low hepcidin in CKD may reflect relative iron depletion, malnutrition, occult blood loss, or a frailty phenotype that is not fully captured by standard covariates. It may also identify patients with less inflammatory upregulation of the hepcidin axis, which would separate them from the subgroup in whom high hepcidin tracks with vascular and renal injury. In practice, a single biomarker can mean different things at different points on the curve.
The finding also prevents overreading hepcidin as a one-directional risk marker. If only elevated values were harmful, the story would be simple. Instead, both tails of the distribution were associated with adverse outcomes, but not the same outcomes. High hepcidin linked to kidney decline and atherosclerosis; low hepcidin linked to death. The biology likely reflects different pathophysiologic states within CKD rather than one linear dose-response relationship.
Why the heart failure and glycemic analyses stayed negative
No association appeared between hepcidin and incident heart failure or prediabetes/diabetes. That negative result matters because it narrows the biomarker’s clinical footprint. Heart failure in CKD is strongly influenced by volume overload, anemia, hypertension, structural heart disease, and myocardial fibrosis, while glycemic progression depends on insulin resistance, beta-cell reserve, and medication exposure. Hepcidin may intersect with those pathways indirectly, but this study did not show a predictive relationship strong enough to emerge after adjustment.
The absence of association also cautions against using hepcidin as a broad surrogate for all cardiometabolic risk in CKD. Its signal appears more specific for renal progression, vascular events, and mortality than for incident heart failure or diabetes onset. For bedside use, that specificity could matter more than breadth.
What this means for CKD risk stratification
This CRIC analysis places hepcidin among the more biologically grounded biomarkers in CKD, but not yet among the most clinically actionable. The results support the idea that iron metabolism is not merely a hematologic side issue in chronic kidney disease; it may be a marker of deeper systemic stress that spills into kidney decline, vascular injury, and survival.
Still, the study does not justify routine hepcidin-guided management. The cohort design cannot prove that modifying hepcidin would improve outcomes, and the biomarker’s divergent associations across endpoints make intervention planning more complicated. A low value may signify one biologic problem, while a high value signals another. Any future trial would have to decide whether to target iron restriction, inflammation, or both, and would need to clarify which patients are most likely to benefit.
For now, the most direct clinical takeaway is narrower but meaningful: in CKD, hepcidin behaves like a bifurcated risk marker. Higher levels tracked with kidney failure progression and atherosclerotic events; lower levels tracked with mortality. That duality argues for more mechanistic work before hepcidin can move from biomarker research into routine nephrology practice.