Protein in red blood cells that carries oxygen throughout the body
21 of 22 providers
Complete Blood Count (CBC)
Men:13.5-17.5 g/dL, Women:12.0-15.5 g/dL
Hemoglobin (Hgb or Hb) is the iron-containing protein in red blood cells responsible for transporting oxygen from your lungs to tissues and carbon dioxide back to lungs for exhalation. Each red blood cell contains about 270 million hemoglobin molecules. Normal hemoglobin levels are 13.5-17.5 g/dL in men and 12.0-15.5 g/dL in women.
Hemoglobin consists of four protein subunits (globin chains) each containing a heme group with an iron atom that binds oxygen. The hemoglobin molecule can carry four oxygen molecules simultaneously. Hemoglobin concentration is the primary criterion for diagnosing anemia (low hemoglobin) and polycythemia (high hemoglobin). Unlike RBC count which measures cell numbers, hemoglobin directly reflects oxygen-carrying capacity.
Hemoglobin is produced in bone marrow and requires iron, vitamin B12, folate, and protein. Each hemoglobin molecule lives 120 days within the RBC. Low hemoglobin causes fatigue, shortness of breath, and reduced exercise tolerance due to inadequate oxygen delivery. High hemoglobin increases blood viscosity and thrombosis risk. Hemoglobin is the single most important parameter from a CBC for assessing overall health and oxygen delivery.
| Range Type | Level | Significance |
|---|---|---|
| Optimal | Men:14.5-16.5 g/dL, Women:13.0-15.0 g/dL | Ideal range for oxygen delivery, energy levels, and cardiovascular health. Athletes often target upper end of this range. Provides adequate oxygen for peak physical and cognitive performance without excessive blood viscosity. |
| Borderline Low | Men:12.0-14.5 g/dL, Women:11.0-13.0 g/dL | Mild anemia or iron deficiency. May cause fatigue, reduced exercise capacity. Check ferritin, iron studies, B12, folate. Treat underlying cause. Athletes with hemoglobin in this range will have impaired performance. |
| Moderate Anemia | 8.0-12.0 g/dL | Moderate anemia causing symptoms (fatigue, dyspnea, tachycardia). Requires investigation and treatment. Check MCV, iron studies, B12, folate, reticulocyte count. Transfusion generally not needed unless symptomatic or actively bleeding. Treat underlying cause aggressively. |
| Severe Anemia or Polycythemia | <8.0 g/dL or >18.0 g/dL | <8 g/dL:Severe anemia. Transfusion typically indicated, especially if symptomatic, unstable, or bleeding. Urgent investigation for cause. >18 g/dL:Severe polycythemia. High thrombosis risk. Urgent phlebotomy and investigation for polycythemia vera or secondary causes. |
Oral iron:Ferrous sulfate 325 mg (65 mg elemental iron) 2-3 times daily on empty stomach. Vitamin C enhances absorption. Hemoglobin should increase 1-2 g/dL per month
IV iron:If oral not tolerated, malabsorption, or need rapid repletion. Iron sucrose, ferric carboxymaltose, iron dextran. Hemoglobin rises within 2-4 weeks
Dietary iron:Red meat (heme iron, best absorbed), spinach, lentils, fortified cereals. Pair with vitamin C
Investigate blood loss:GI endoscopy if unexplained iron deficiency. Treat menorrhagia if heavy periods cause
Duration:Continue iron 3-6 months after hemoglobin normalizes to replenish stores (ferritin >50 ng/mL)
B12 deficiency (high MCV):B12 1000 mcg IM weekly for 4-8 weeks, then monthly lifelong. Or oral B12 1000-2000 mcg daily. Hemoglobin improves in 1-2 months
Folate deficiency:Folic acid 1-5 mg daily. Hemoglobin normalizes in 4-8 weeks. Common in pregnancy, alcoholism, malabsorption
Address cause:Pernicious anemia (autoimmune), gastric bypass, vegan diet (B12), alcoholism (folate), medications (methotrexate depletes folate)
Don't miss B12:Always check B12 before treating with folate alone—folate can mask B12 deficiency while nerve damage progresses
Treat underlying condition:Inflammatory bowel disease, rheumatoid arthritis, cancer, chronic kidney disease
Erythropoietin-stimulating agents (ESAs):If hemoglobin <10 g/dL from chronic kidney disease or chemotherapy. Epoetin alfa or darbepoetin. Target hemoglobin 10-11 g/dL (not higher—increases thrombosis risk)
Iron supplementation:IV iron often needed with ESAs. Functional iron deficiency common in chronic disease despite normal ferritin
Anti-inflammatory therapy:Reduce cytokines (IL-6, TNF-alpha) that suppress EPO and iron utilization
Transfusion:If hemoglobin <7-8 g/dL and symptomatic, transfuse to hemoglobin 8-10 g/dL
Polycythemia vera:Phlebotomy to maintain hemoglobin <14.5 g/dL (men), <13 g/dL (women). Aspirin 81 mg daily. Hydroxyurea if high risk
Secondary polycythemia:Treat cause (CPAP for sleep apnea, smoking cessation, oxygen for lung disease). Phlebotomy if hemoglobin >18 g/dL and symptomatic
Dehydration:Rehydrate with 2-3 liters fluids. Recheck after hydration—should normalize if relative polycythemia
Testosterone-induced:Reduce dose or stop. Monitor hemoglobin every 3 months on testosterone therapy
Maintain iron stores:Ferritin >50 ng/mL (>100 for athletes). Supplement if needed to optimize hemoglobin production
Altitude training:Living/training at altitude increases hemoglobin. Athletes use this to enhance oxygen capacity
Adequate protein:1.0-1.2 g/kg daily provides amino acids for globin chains
Optimize EPO production:Adequate sleep (EPO produced during sleep), avoid chronic kidney disease, treat sleep apnea
Blood doping (illegal):EPO injections or blood transfusions artificially increase hemoglobin. Banned in sports due to health risks and unfair advantage
For athletes:Target hemoglobin 15-16 g/dL for males, 14-15 g/dL for females for optimal endurance performance
World Health Organization defines anemia as hemoglobin <13 g/dL in men, <12 g/dL in non-pregnant women, and <11 g/dL in pregnant women. These thresholds are based on population distributions and associated with increased morbidity, reduced quality of life, and impaired physical/cognitive function. Anemia affects 1.6 billion people worldwide.
Source:WHO. Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity. 2011.
Restrictive transfusion strategy (transfuse only if hemoglobin <7 g/dL in stable patients) is as safe as liberal strategy (transfuse at <10 g/dL) and reduces blood usage by 40%. Exception:acute coronary syndrome patients benefit from hemoglobin >8 g/dL. These findings changed transfusion practice worldwide.
Source:Hébert PC, et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. N Engl J Med. 1999;340(6):409-417.
Oral iron therapy (ferrous sulfate 200 mg 2-3 times daily) increases hemoglobin by 1-2 g/dL per month in iron deficiency anemia. IV iron produces faster response (2-4 weeks) and is superior when oral iron fails, malabsorption exists, or rapid repletion needed. Hemoglobin >12 g/dL is achieved in 90% of patients by 3 months.
Source:Goddard AF, et al. Guidelines for the management of iron deficiency anaemia. Gut. 2011;60(10):1309-1316.
In chronic kidney disease patients on dialysis, targeting higher hemoglobin (13-15 g/dL) with ESAs increases stroke and cardiovascular events compared to targeting 10-11 g/dL, without improving quality of life. Current guidelines recommend ESA use only if hemoglobin <10 g/dL, targeting 10-11 g/dL to avoid cardiovascular risks.
Source:KDOQI. Clinical Practice Guideline for Anemia in Chronic Kidney Disease. Am J Kidney Dis. 2012;60(5):850-886.
Hemoglobin directly correlates with VO2 max (maximal oxygen uptake) and endurance performance. Each 1 g/dL increase in hemoglobin improves VO2 max by ~4% in endurance athletes. This explains the performance advantage of altitude training (increases hemoglobin) and the use (and banning) of EPO doping in competitive sports.
Source:Calbet JA, et al. Importance of hemoglobin concentration to exercise:acute manipulations. Respir Physiol Neurobiol. 2006;151(2-3):132-140.
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $349 | 100+ | |
 InsideTracker | ✓ | $680 | 54 |
 Function Health | ✓ | $365 | 100+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| — | $399 | 100+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| ✓ | $125 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 129 |
21 providers include this biomarker in their panels
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
