Differential Diagnosis of Elevated Ferritin
Elevated ferritin is most commonly caused by inflammation, chronic liver disease, malignancy, and infection—accounting for over 90% of cases—not iron overload. 1
Algorithmic Diagnostic Approach
The critical first step is measuring transferrin saturation (TS) simultaneously with ferritin to distinguish true iron overload from secondary causes. 1, 2
When TS ≥45%: Primary Iron Overload
If TS ≥45%, suspect primary iron overload and proceed immediately to HFE genetic testing for C282Y and H63D mutations. 1, 2
Primary iron overload disorders include:
- Hereditary hemochromatosis (HFE-related): C282Y homozygosity or C282Y/H63D compound heterozygosity 1, 2
- Non-HFE hemochromatosis: Mutations in TFR2, SLC40A1, HAMP, or HJV genes 1, 2
When TS <45%: Secondary Hyperferritinemia
If TS <45%, iron overload is unlikely and secondary causes predominate—do not proceed to genetic testing. 1, 2 Over 90% of elevated ferritin cases fall into this category. 1
Complete Differential by Category
Liver Disease (Most Common)
- Chronic alcohol consumption: Increases iron absorption and causes hepatocellular injury 1, 2
- Non-alcoholic fatty liver disease (NAFLD)/metabolic syndrome: Ferritin elevation reflects hepatocellular injury and insulin resistance rather than iron overload 1, 2
- Viral hepatitis (B and C) 2
- Acute hepatitis and cirrhosis 2
- Hepatocellular carcinoma 2
Inflammatory/Infectious Conditions
- Acute and chronic infections: Ferritin rises as an acute phase reactant during active infection 1, 3, 4
- Systemic inflammatory response syndrome 2
- Chronic rheumatologic diseases 2
- Adult-onset Still's disease (AOSD): Ferritin typically 4,000-30,000 ng/mL with glycosylated ferritin fraction <20% (93% specific for AOSD) 1, 2
- Hemophagocytic lymphohistiocytosis (HLH): Consider when ferritin >10,000 μg/L with fever, cytopenias, and multiorgan dysfunction 1, 4, 5
Malignancy
- Solid tumors 2
- Lymphomas 2
- Hematologic malignancies: T/NK cell lymphoma, acute myeloblastic leukemia 3
- Hepatocellular carcinoma 2
Cellular Damage/Necrosis
- Cell necrosis: Muscle injury, hepatocellular necrosis, or tissue breakdown releases ferritin from lysed cells independent of iron stores 1, 2
Other Conditions
- Chronic kidney disease: Especially in patients on erythropoiesis-stimulating agents 1
- Diabetes mellitus/metabolic syndrome 2
- Transfusional iron overload: Chronic transfusions 6, 5
- Sickle cell disease 6
Risk Stratification by Ferritin Level
Understanding ferritin magnitude helps narrow the differential:
- Ferritin <1,000 μg/L: Low risk of organ damage; 94% negative predictive value for advanced fibrosis 1, 2
- Ferritin 1,000-10,000 μg/L: Higher risk of advanced fibrosis/cirrhosis if iron overload is present; in C282Y homozygotes with elevated liver enzymes and platelet count <200,000/μL, predicts cirrhosis in 80% 1, 2
- Ferritin >10,000 μg/L: Rarely represents simple iron overload; strongly suggests life-threatening conditions such as HLH, adult-onset Still's disease, or severe hepatocellular injury requiring urgent specialist referral 1, 4, 5
Critical Diagnostic Pitfalls to Avoid
Never use ferritin alone without transferrin saturation to diagnose iron overload. 1, 2 Ferritin is an acute phase reactant that rises during inflammation, infection, liver disease, malignancy, and tissue necrosis independent of actual iron stores. 1, 2
Do not assume iron overload when TS <45%—in the general population, iron overload is NOT the most common cause of elevated ferritin. 1, 2
Do not overlook liver biopsy in patients with ferritin >1,000 μg/L and abnormal liver tests, as this combination warrants histologic assessment for cirrhosis. 1, 2
Recognize that extremely high ferritin (>10,000 μg/L) rarely represents simple iron overload and requires urgent evaluation for HLH, adult-onset Still's disease, or severe hepatocellular injury. 1, 4, 5
Special Clinical Contexts
Chronic Kidney Disease
In CKD patients on erythropoiesis-stimulating agents, ferritin 500-1,200 ng/mL with TS <25% may represent functional iron deficiency that responds to IV iron therapy despite elevated ferritin. 1
Adult-Onset Still's Disease
If ferritin rises above 4,000-5,000 ng/mL with persistent fever, measure glycosylated ferritin fraction—a value <20% is 93% specific for AOSD. 1, 2
Critically Ill Patients
In critically ill patients with hyperferritinemia ≥500 μg/L, the most important differential diagnoses are sepsis/septic shock, liver disease, and hematological malignancy—together with HLH, these form the "quartet" of critical diagnoses. 3 Always apply HLH-2004 criteria to exclude HLH in this population. 3