Complete Testing & Optimization Guide
Optimal ranges, provider comparison, and strategies to improve your Hematocrit levels
Included in 10 of 10 major testing providers
Complete Blood Count (CBC)
Men:38-50%, Women:35-45%
Abnormal Hematocrit levels can indicate underlying health issues that may go undetected without proper testing. Regular monitoring helps catch problems early when they're most treatable.
Understanding your Hematocrit levels enables targeted interventions, tracks treatment effectiveness, and helps optimize your overall health and performance.
Hematocrit (Hct) is the percentage of blood volume occupied by red blood cells. Normal hematocrit is 38-50% in men and 35-45% in women. If your hematocrit is 45%, it means that 45% of your blood volume consists of red blood cells, while the remaining 55% is plasma (the liquid component).
Hematocrit is directly related to hemoglobin and RBC count—it is essentially a mathematical derivative of these values. The relationship is:Hematocrit ≈ Hemoglobin × 3 (e.g., hemoglobin 15 g/dL ≈ hematocrit 45%). Hematocrit reflects blood viscosity and oxygen-carrying capacity. Higher hematocrit means thicker blood, which can impair circulation if excessive.
Hematocrit is affected by hydration status more than hemoglobin or RBC count. Dehydration concentrates RBCs, falsely elevating hematocrit, while overhydration dilutes RBCs, lowering hematocrit. This makes hematocrit useful for assessing volume status. In clinical practice, hemoglobin is preferred over hematocrit for diagnosis and management because it directly measures oxygen-carrying capacity.
Bottom line: TSH and Free T4 alone miss people with conversion problems. Free T3 is the only way to know if you have enough active thyroid hormone at the tissue level.
| Range Type | Level | Clinical Significance |
|---|---|---|
| Optimal | Men:42-48%, Women:38-43% | Ideal range balancing oxygen delivery with blood fluidity. Provides adequate oxygen without excessive viscosity. Supports optimal cardiovascular function and tissue perfusion. |
| Borderline | Men:36-42% or 48-52%, Women:33-38% or 43-48% | Low-normal may indicate mild anemia or hemodilution. High-normal may indicate mild polycythemia or dehydration. Check hemoglobin, hydration status. Retest after proper hydration. |
| Anemia | <36% (men), <33% (women) | Indicates anemia. Severity:Mild 30-36%, Moderate 24-30%, Severe <24%. Investigate cause with iron studies, B12, folate, reticulocyte count. Transfusion typically not needed unless <21% with symptoms. |
| Polycythemia | >52% (men), >48% (women) | Elevated hematocrit increases blood viscosity and thrombosis risk exponentially above 50%. Requires investigation for polycythemia vera, secondary polycythemia, or dehydration. Urgent phlebotomy if >60% or symptomatic. |
Standard lab range:Men:38-50%, Women:35-45%
Iron supplementation:Ferrous sulfate 325 mg 2-3x daily. Hematocrit increases 3-6% per month
B12/Folate replacement:As per hemoglobin guidelines. Hematocrit normalizes in 1-3 months
ESAs for chronic disease:Target hematocrit 30-36% (hemoglobin 10-12 g/dL)
Transfusion:Each unit packed RBCs increases hematocrit by ~3%. Transfuse if <21-24% with symptoms
Phlebotomy:Remove 250-500 mL blood every 2-7 days until hematocrit <45% (men) or <42% (women). The CYTO-PV trial established <45% as the target
Aspirin:81 mg daily reduces thrombosis in polycythemia vera by 30-40%
Hydroxyurea:If high thrombosis risk (age >60, prior clot). Reduces hematocrit and platelet count
Hydration:Ensure 2-3 liters fluids daily. Dehydration worsens viscosity effects
If elevated hematocrit with normal hemoglobin:Likely dehydration. Increase fluids to 2-3 liters daily and retest
Calculate plasma volume:In dehydration, both hemoglobin and hematocrit rise proportionally. In polycythemia, RBC mass is truly increased
Monitor urine:Dark urine suggests dehydration. Aim for pale yellow urine
IV fluids:If severe dehydration, may need 1-2 liters IV saline before accurate hematocrit assessment
Expected drop:Hematocrit falls 5-7% in pregnancy due to 40-50% plasma volume expansion (physiologic anemia of pregnancy)
True anemia threshold:Hematocrit <33% (hemoglobin <11 g/dL) in pregnancy indicates iron deficiency
Iron supplementation:30-60 mg elemental iron daily throughout pregnancy. Increase to 120 mg if anemic
Recheck:Monthly hematocrit in pregnancy, more frequent if anemic
Physiologic increase:Hematocrit rises 1-2% for every 1000m elevation above sea level. At 3000m (10,000 ft), hematocrit may reach 50-55%
Chronic mountain sickness:Excessive polycythemia (hematocrit >60%) at altitude impairs oxygen delivery due to hyperviscosity
Treatment:Descent to lower altitude, phlebotomy if symptomatic, acetazolamide to reduce EPO drive
Athletes:Altitude training increases hematocrit 3-5% over 3-4 weeks, enhancing endurance performance for weeks after descent
Note: Symptoms correlate with hematocrit level:<30% causes symptoms with exertion, <24% causes symptoms at rest, <18% is life-threatening.
Note: Above 50%, blood viscosity increases exponentially. Hematocrit >60% is a medical emergency due to severe hyperviscosity and impending thrombosis.
The CYTO-PV trial randomized polycythemia vera patients to hematocrit target <45% vs <50%. The <45% group had 50% lower rate of cardiovascular death and major thrombosis. This established hematocrit <45% as the treatment target for polycythemia vera.
Source:Marchioli R, et al. Cardiovascular events and intensity of treatment in polycythemia vera. N Engl J Med. 2013;368(1):22-33.
Blood viscosity increases linearly with hematocrit up to 45%, then exponentially above 50%. Hematocrit of 60% doubles blood viscosity compared to 40%. This impairs microvascular flow, reduces oxygen delivery despite high oxygen content, and dramatically increases thrombosis risk.
Source:Pearson TC, et al. Rheological factors in the pathogenesis of arterial disease in polycythemia vera. J R Soc Med. 1978;71(11):813-818.
Plasma volume increases 40-50% in pregnancy while RBC mass increases only 20-30%, causing dilutional drop in hematocrit of 5-7%. This "physiologic anemia"is normal. True anemia (hematocrit <33% or hemoglobin <11 g/dL) indicates iron deficiency requiring supplementation.
Source:Bothwell TH. Iron requirements in pregnancy and strategies to meet them. Am J Clin Nutr. 2000;72(1 Suppl):257S-264S.
Acute dehydration causes hemoconcentration, increasing hematocrit 1-2% for every 2% loss of body weight. This makes hematocrit useful for assessing hydration status in acute illness. However, chronic dehydration does not significantly elevate hematocrit as compensatory mechanisms maintain plasma volume.
Source:Popowski LA, et al. Blood and urinary measures of hydration status during progressive acute dehydration. Med Sci Sports Exerc. 2001;33(5):747-753.
Hematocrit increases ~1% for every 1000m above sea level as physiologic adaptation to reduced oxygen. Long-term residents at 4000m have hematocrit 50-55%. However, excessive polycythemia (>60%) indicates chronic mountain sickness with impaired oxygen delivery due to hyperviscosity.
Source:León-Velarde F, et al. Chronic mountain sickness. Respir Physiol Neurobiol. 2007;158(2-3):151-165.
| Provider | Includes Test | Annual Cost | Total Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $798 | 100+ | |
 InsideTracker | ✓ | $680 | 48 |
 Function Health | ✓ | $499 | 100+ |
| ✓ | $900 | 70+ | |
| ✓ | $1150 | 110 | |
| — | $Varies | 75+ |
Choose from 10 providers that include this biomarker in their panels
Hematocrit is a complete blood count (cbc) biomarker that Percentage of blood volume occupied by red blood cells The normal reference range is Men:38-50%, Women:35-45%. Regular testing helps track changes and identify potential health issues early.
10 out of 10 major blood testing providers include Hematocrit in their standard panels. These include Superpower, Blueprint, Mito Health and others.
For most people, testing Hematocrit 2-4 times per year is recommended to establish baseline levels and track trends. If you have abnormal results or are actively working to optimize this biomarker, more frequent testing (quarterly) may be beneficial. Always consult with your healthcare provider for personalized testing frequency recommendations.
The standard laboratory reference range for Hematocrit is Men:38-50%, Women:35-45%. However, many functional medicine practitioners recommend tighter "optimal" ranges for peak health and performance. Your ideal range may vary based on your age, sex, health goals, and other individual factors. Work with a healthcare provider familiar with optimal ranges to determine your target levels.
Most direct-to-consumer blood testing services that include Hematocrit provide the physician order as part of their service. However, some states have restrictions on direct-to-consumer testing. Check with your chosen provider about availability in your state and whether they provide the necessary physician authorization.
Indicates blood's oxygen-carrying capacity. Low values suggest anemia;high values may indicate dehydration or lung disease. Used to diagnose and monitor blood disorders.
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs and before making decisions about blood testing.
