Iron (Serum)
Iron in blood plasma
16 of 22 providers
Vitamins &Nutrients
Men:65-175 μg/dL, Women:50-170 μg/dL
What is Iron (Serum)?
Serum iron measures the amount of iron currently circulating in your bloodstream, bound to transferrin (the iron transport protein). Unlike ferritin (which reflects iron stores), serum iron reflects the iron available for immediate use by cells. Serum iron fluctuates significantly throughout the day and is influenced by recent meals, inflammation, and diurnal variation (highest in morning, lowest at night). Because of this variability, serum iron alone is not a reliable marker of iron status—it must be interpreted alongside ferritin, TIBC (total iron-binding capacity), and transferrin saturation.
Here's the critical insight:serum iron, TIBC, and transferrin saturation work together to paint a complete picture of iron status. Low serum iron + high TIBC + low transferrin saturation=iron deficiency (body desperately trying to capture more iron). High serum iron + low TIBC + high transferrin saturation (>45%)=iron overload (hemochromatosis). Normal serum iron + low TIBC=anemia of chronic disease (inflammation sequesters iron). You can't interpret serum iron in isolation—you need the full iron panel.
Transferrin saturation is the most useful calculated value:(Serum Iron / TIBC) × 100. Normal is 20-45%. <20% indicates iron deficiency;>45% suggests iron overload. Transferrin saturation <20% with ferritin <30 ng/mL confirms iron deficiency anemia. Transferrin saturation >45% with ferritin >300 ng/mL (men) or >200 ng/mL (women) suggests hemochromatosis—genetic testing for HFE mutations is warranted.
Why Serum Iron Matters (As Part of Full Iron Panel)
- Diagnose iron deficiency vs anemia of chronic disease:Low serum iron can be due to true iron deficiency OR inflammation. TIBC and ferritin differentiate:iron deficiency (high TIBC, low ferritin) vs chronic disease (low TIBC, normal/high ferritin).
- Detect iron overload (hemochromatosis):High serum iron + high transferrin saturation (>45%) indicates excessive iron absorption. Hemochromatosis causes cirrhosis, diabetes, heart failure if untreated.
- Guide iron supplementation:If transferrin saturation <20% and ferritin <30 ng/mL, iron supplementation is clearly indicated. Monitor transferrin saturation and ferritin to track response.
- Evaluate unexplained fatigue or anemia:Serum iron (with TIBC, ferritin, transferrin saturation) identifies the cause:iron deficiency, chronic disease, hemochromatosis, or other.
Optimal vs Standard Ranges
Optimal (with TIBC and Transferrin Saturation)60-170 mcg/dL (men) 50-150 mcg/dL (women)▼
- Normal range for serum iron
- Must interpret with TIBC and transferrin saturation (optimal 25-35%)
Low Serum Iron<50 mcg/dL▼
- Low serum iron
- Check TIBC and ferritin:| If TIBC high (>400) + ferritin low (<30)=iron deficiency
- | If TIBC low (<250) + ferritin normal/high=anemia of chronic disease (inflammation)
High Serum Iron>200 mcg/dL▼
- High serum iron
- Check TIBC and transferrin saturation:| If transferrin saturation >45% + ferritin >300 (men) or >200 (women)=possible hemochromatosis
- | If acute, may be from recent iron supplementation, blood transfusion, or hemolysis
Low Transferrin Saturation<20%▼
- Iron deficiency
- Body can't saturate transferrin with iron
- Supplement with iron (ferrous bisglycinate 25-50 mg daily)
Scientific Evidence
Low serum iron with high TIBC and low ferritin=iron deficiency. Low serum iron with low TIBC and normal/high ferritin=anemia of chronic disease.
High serum iron with transferrin saturation >45% may indicate hemochromatosis:|Joint pain, especially knuckles (iron deposits in joints)|Fatigue, weakness|Abdominal pain, liver enlargement|Loss of libido, erectile dysfunction|Bronze or gray skin discoloration|Diabetes (iron damages pancreas)|Cirrhosis, liver cancer|Heart arrhythmias, cardiomyopathy|Arthritis, especially hands
True iron deficiency:Low dietary iron (vegetarian/vegan), heavy menstrual bleeding, GI blood loss, malabsorption (celiac, gastric bypass).|Anemia of chronic disease:Chronic infections (TB, HIV), autoimmune diseases (rheumatoid arthritis, lupus), cancer, chronic kidney disease. Inflammation (high CRP, IL-6) causes hepcidin release, which sequesters iron in macrophages, lowering serum iron.|Pregnancy:Increased iron demand lowers serum iron and ferritin.|Recent blood donation:Acutely lowers serum iron and ferritin.
Hereditary hemochromatosis:HFE gene mutations (C282Y, H63D) cause excessive iron absorption from diet. Most common genetic disorder in Caucasians (1:200-300).|Frequent blood transfusions:Chronic anemia (thalassemia, sickle cell) requiring transfusions → iron overload.|Excessive iron supplementation:Taking high-dose iron without deficiency.|Acute iron ingestion:Iron poisoning (accidental or intentional overdose).|Hemolysis:Red blood cell destruction releases iron into bloodstream (hemolytic anemia, transfusion reaction).|Acute hepatitis or liver necrosis:Damaged hepatocytes release stored iron.
Transferrin Saturation as Key Diagnostic
Transferrin saturation (serum iron / TIBC × 100) is more useful than serum iron alone. <20%=iron deficiency;>45%=iron overload. Transferrin saturation <16% in combination with ferritin <30 ng/mL has 90% sensitivity and specificity for iron deficiency anemia.
Source:Guyatt GH, et al. Laboratory diagnosis of iron-deficiency anemia:an overview. J Gen Intern Med. 1992;7(2):145-153.
Anemia of Chronic Disease vs Iron Deficiency
Anemia of chronic disease (ACD) is the second most common anemia after iron deficiency. Inflammation (infections, autoimmune disease, cancer) releases hepcidin, which traps iron in macrophages, lowering serum iron but raising/maintaining ferritin. ACD:low serum iron, low TIBC, normal/high ferritin. Iron deficiency:low serum iron, high TIBC, low ferritin.
Source:Weiss G, Goodnough LT. Anemia of chronic disease. N Engl J Med. 2005;352(10):1011-1023.
Hemochromatosis Diagnosis and Treatment
Hereditary hemochromatosis is diagnosed with transferrin saturation >45% (most sensitive early marker), ferritin >300 (men) or >200 (women), and HFE genetic testing (C282Y homozygous most common). Treatment is phlebotomy:remove 500 mL blood weekly until ferritin <50 ng/mL, then maintenance every 2-3 months. Prevents cirrhosis, diabetes, heart disease.
Source:Bacon BR, et al. Diagnosis and management of hemochromatosis:2011 practice guideline by AASLD. Hepatology. 2011;54(1):328-343.
Which Providers Test Iron (Serum)?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | — | $398 | 30+ |
| — | $486 | 40+ | |
| — | $444 | 288 | |
| ✓ | $349 | 100+ | |
| ✓ | $761 | 54 | |
 Function Health | ✓ | $365 | 160+ |
| — | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| ✓ | $375 | 80+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| — | $99 | 50 | |
| ✓ | $124 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 70-80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 128 |
Frequently Asked Questions
What is Iron (Serum)?
Iron in blood plasma
What is the optimal range for Iron (Serum)?
The standard reference range for Iron (Serum) is Men:65-175 μg/dL, Women:50-170 μg/dL. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include Iron (Serum)?
16 out of 22 blood testing providers include Iron (Serum) in their panels. This biomarker is widely available across major providers.
What category does Iron (Serum) fall under?
Iron (Serum) is categorized under Vitamins &Nutrients. This category includes biomarkers that help assess related aspects of health and wellness.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed:2026-02-20