The ferritin test measures the level of ferritin in blood — a protein that stores iron throughout the body. Serum ferritin reflects total body iron stores. The test is used to evaluate both iron deficiency and iron overload. Normal range: 30-300 ng/mL in men; 15-200 ng/mL in women (varies by lab and age). Low ferritin (under 30) indicates iron deficiency. High ferritin (over 200 in men, 150 in women) may indicate iron overload, inflammation, infection, liver disease, or hemochromatosis. For adults with diabetes, ferritin matters because: iron overload increases diabetes risk; elevated ferritin in T2D may reflect inflammation; iron deficiency is common with chronic disease. Iron overload (hereditary hemochromatosis from HFE gene mutations) causes iron deposits in pancreas damaging beta cells — 25-50% of adults with hemochromatosis develop diabetes. Hemochromatosis affects 1 in 200-300 adults of Northern European descent — more common than typically recognized. Screening: serum ferritin + transferrin saturation; HFE genetic testing if suspected; treatment with therapeutic phlebotomy. Many adults with T2D have elevated ferritin from chronic inflammation rather than true iron overload — transferrin saturation distinguishes (high over 45% suggests overload; normal/low suggests inflammation). For iron deficiency: investigate cause, oral iron supplements (ferrous sulfate, ferrous gluconate, or iron bisglycinate better tolerated), take with vitamin C for absorption, avoid coffee/tea with doses, IV iron for severe cases, dietary iron from red meat (heme, well-absorbed) or plant sources with vitamin C. Recheck after 3 months.
Ferritin Reference Ranges
| Ferritin (ng/mL) | Interpretation | Action |
|---|---|---|
| under 15 (women) / under 30 (men) | Iron deficiency | Investigate cause; supplement |
| 15-30 (women) / 30-100 (men) | Low-normal | Often okay; check if symptoms |
| 30-200 (women) / 100-300 (men) | Normal | No action |
| 200-500 (women) / 300-500 (men) | Mildly elevated | Check transferrin saturation; investigate cause |
| 500-1,000 | Significantly elevated | Investigate hemochromatosis, liver disease, inflammation |
| over 1,000 | Severely elevated | Hemochromatosis evaluation; consider liver biopsy |
Iron Overload and Diabetes
- Hereditary hemochromatosis (HFE gene mutations) — most common form.
- 1 in 200-300 adults of Northern European descent affected.
- Iron deposits in pancreas damage beta cells.
- 25-50% develop diabetes (“bronze diabetes” in advanced cases).
- Iron overload also damages liver, heart, joints.
- Screening: serum ferritin + transferrin saturation.
- Confirmation: HFE genetic testing.
- Treatment: therapeutic phlebotomy (regular blood draws) — effective and inexpensive.
- Earlier treatment prevents complications including diabetes.
Distinguishing Inflammation from Iron Overload
| Pattern | Ferritin | Transferrin Saturation | Implication |
|---|---|---|---|
| Iron deficiency | Low | Low | Treat deficiency |
| Iron overload | High | High (over 45%) | Investigate hemochromatosis |
| Inflammation/chronic disease | High | Normal or low | Treat underlying inflammation |
| Fatty liver disease | Modestly high | Normal | Treat NAFLD |
| Dysmetabolic iron overload | Modestly high | Normal/low | Metabolic syndrome management |
Symptoms of Iron Deficiency
- Fatigue and weakness.
- Pale skin.
- Shortness of breath with exertion.
- Brittle nails.
- Hair loss.
- Headaches.
- Restless legs syndrome.
- Cold hands and feet.
- Pica (cravings for non-food items like ice, dirt, clay).
- Reduced exercise tolerance.
- Tongue inflammation.
- Mouth ulcers.
Symptoms of Iron Overload
- Often asymptomatic in early stages.
- Joint pain (especially second and third knuckles).
- Fatigue (paradoxically, can mimic deficiency).
- Abdominal pain.
- Skin darkening (“bronze” appearance in advanced cases).
- Liver dysfunction.
- Heart problems (arrhythmias, heart failure).
- Diabetes onset.
- Sexual dysfunction (low testosterone in men).
- Hypothyroidism.
Iron Supplementation
- Ferrous sulfate 325 mg (65 mg elemental iron) 1-3x daily.
- Ferrous gluconate — alternative; better tolerated for some.
- Iron bisglycinate — chelated form; least GI side effects.
- Take with vitamin C for absorption.
- Avoid coffee, tea, calcium, antacids with doses.
- GI side effects common (constipation, dark stools, nausea).
- Liquid iron forms available for adults with swallowing issues.
- IV iron for severe deficiency, GI intolerance, or absorption issues.
- Recheck after 3 months.
- Treatment typically 3-6 months minimum.
Dietary Iron Sources
- Heme iron (well-absorbed): red meat, organ meats, poultry, fish, shellfish.
- Non-heme iron (less absorbed): spinach, lentils, beans, fortified cereals, tofu, pumpkin seeds, dark chocolate.
- Eat non-heme sources with vitamin C (citrus, tomatoes, peppers) to enhance absorption.
- Avoid tea, coffee, calcium-rich foods at same meal.
- Heme iron from meat absorbed 15-35%.
- Non-heme iron absorbed 2-20% depending on context.
- Vegetarians/vegans need more dietary planning to meet iron needs.
Diabetes-Specific Considerations
- Adults with type 2 diabetes often have elevated ferritin from chronic inflammation.
- Don’t assume iron overload — check transferrin saturation.
- Treating underlying conditions (NAFLD, obesity) often normalizes ferritin.
- HFE testing if both ferritin and transferrin saturation elevated.
- For diabetic women with heavy menstrual bleeding: monitor for iron deficiency.
- For diabetic men with chronic disease: monitor for elevated ferritin patterns.
- Therapeutic phlebotomy for hemochromatosis improves both iron status and glucose.
The Bottom Line
The ferritin test measures iron stores. Normal range: 30-300 ng/mL in men; 15-200 ng/mL in women. Low ferritin (under 30) indicates iron deficiency; high ferritin (over 200 in men, 150 in women) may indicate iron overload, inflammation, infection, liver disease, or hemochromatosis. For adults with diabetes, ferritin matters because: iron overload increases diabetes risk; elevated ferritin in T2D may reflect inflammation rather than true overload; iron deficiency is common. Iron overload (hereditary hemochromatosis from HFE gene mutations) causes iron deposits in pancreas damaging beta cells — 25-50% of adults with hemochromatosis develop diabetes. Hemochromatosis affects 1 in 200-300 adults of Northern European descent. Screening: serum ferritin + transferrin saturation; high ferritin + high saturation (over 45%) suggests overload; high ferritin + normal/low saturation suggests inflammation. HFE genetic testing confirms hemochromatosis. Treatment: therapeutic phlebotomy (regular blood draws) — effective and inexpensive; prevents complications including diabetes if early. Adults with type 2 diabetes often have modestly elevated ferritin from chronic inflammation, fatty liver disease (NAFLD common in T2D), or dysmetabolic iron overload syndrome — treat underlying conditions (lose weight, treat NAFLD) often normalizes ferritin. For iron deficiency: investigate cause (menstrual blood loss, GI bleeding, malabsorption), oral iron supplements (ferrous sulfate 325 mg 1-3x daily, ferrous gluconate, or iron bisglycinate better tolerated), take with vitamin C, avoid coffee/tea/calcium with doses, IV iron for severe cases. Dietary iron from red meat (heme, 15-35% absorbed) or plant sources with vitamin C (non-heme, 2-20% absorbed). Recheck ferritin after 3 months of treatment. Symptoms of deficiency: fatigue, pale skin, shortness of breath, brittle nails, hair loss, restless legs syndrome, cold extremities, pica. Symptoms of overload: often asymptomatic early; joint pain, fatigue, abdominal pain, skin darkening, liver dysfunction. For adults with type 2 diabetes, ferritin testing in evaluation can identify treatable iron overload (hemochromatosis) that contributes to diabetes; can also identify iron deficiency requiring treatment. See our broader diabetes detection guide for context.
