Is a ferritin level of 108 ng/mL and an iron level of 494 mcg/dL concerning for an obese 16-year-old female?

Elevated Ferritin and Iron in an Obese Adolescent Female

This ferritin level of 108 ng/mL is NOT concerning and falls within the normal reference range for females (20-200 ng/mL), while the iron level of 494 mcg/dL is markedly elevated and requires further evaluation with transferrin saturation to determine if true iron overload exists. 1

Understanding the Clinical Context

In obesity, ferritin behaves primarily as an inflammatory marker rather than a reliable indicator of iron stores. 2 This is critical because:

• Ferritin has a strong positive correlation with BMI (r = 0.86) and C-reactive protein (r = 0.87) in overweight and obese individuals, while showing strong negative correlation with actual iron parameters including transferrin saturation. 2
• Approximately 90% of hyperferritinemia cases in clinical practice are NOT due to iron overload, but rather reflect inflammation, metabolic syndrome, or other secondary causes. 3, 4
• In obese patients, ferritin should not be used as a reliable index of iron status without additional testing. 5

Immediate Next Steps Required

You must measure fasting transferrin saturation (TS) immediately - this is the single most important test to distinguish true iron overload from secondary causes of elevated iron parameters. 3

Interpretation Algorithm:

If TS ≥45%:

• Suspect primary iron overload (hereditary hemochromatosis)
• Order HFE genetic testing for C282Y and H63D mutations 1, 3
• C282Y homozygosity with elevated iron stores confirms HFE hemochromatosis 1

If TS <45%:

• Iron overload is unlikely 3
• The elevated serum iron likely reflects inflammation, metabolic syndrome, or laboratory variation 1, 3
• Focus on evaluating for obesity-related metabolic complications 2, 5

Additional Evaluation Needed

Check inflammatory markers and metabolic parameters:

• C-reactive protein (CRP) and ESR to assess inflammation 3
• Complete metabolic panel including AST, ALT to evaluate hepatocellular injury 3
• Fasting glucose and lipid panel to screen for metabolic syndrome 5

The combination of obesity and diabetes is the main contributor to elevated ferritin levels, independent of actual iron stores. 5 Non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome account for a substantial proportion of hyperferritinemia in obese patients. 3

Critical Clinical Pearls

• Ferritin <1000 μg/L has a 94% negative predictive value for advanced liver fibrosis in hemochromatosis patients, so this level of 108 ng/mL carries minimal risk even if iron overload were present. 3
• In obesity, ferritin elevation reflects insulin resistance and hepatocellular injury rather than iron overload in most cases. 3
• Serum iron levels have significant day-to-day variation and are affected by inflammation, making a single elevated value less concerning without confirmatory transferrin saturation. 1

Common Pitfalls to Avoid

• Never use ferritin alone without transferrin saturation to diagnose iron overload - this is the most common diagnostic error. 3
• Do not assume iron overload based on elevated serum iron alone - TS is required for accurate assessment. 1, 3
• Do not overlook metabolic syndrome as the primary driver of abnormal iron parameters in obese adolescents. 2, 5
• Recognize that in obesity, complete iron profile including transferrin is needed rather than ferritin alone to truly predict iron status. 2

Bottom Line

The ferritin of 108 ng/mL is normal and not concerning. The elevated iron of 494 mcg/dL requires transferrin saturation measurement to determine significance - if TS <45%, this likely represents inflammation or metabolic effects of obesity rather than true iron overload. 1, 3, 2 Focus your evaluation on screening for metabolic syndrome, NAFLD, and obesity-related complications rather than iron overload disorders. 3, 5