Hematocrit – Everything You Need to Know

Hematocrit (HCT) is the percentage of red blood cells (RBCs) in your blood. It plays a crucial role in oxygen delivery and overall blood viscosity.

1. What is Hematocrit? #

Hematocrit is the proportion of your blood made up of RBCs, typically expressed as a percentage. A normal range depends on age, sex, and overall health:

• Men: 40-50%
• Women: 36-44%
• Elite Athletes: May have slightly lower or higher levels depending on training adaptations.

It is measured via a Complete Blood Count (CBC) test.

2. Why is Hematocrit Important? #

Hematocrit is vital because it affects:

• Oxygen transport: RBCs carry oxygen, so too low HCT can cause fatigue.
• Blood viscosity: High HCT thickens the blood, increasing the risk of clotting, high blood pressure, and cardiovascular issues.
• Exercise performance: Higher HCT can improve endurance (more oxygen delivery), but too high can be dangerous.

3. Factors That Influence Hematocrit

A. Natural Factors

• Hydration levels: Dehydration increases HCT (less plasma volume), while overhydration lowers it.
• Altitude: Higher elevations trigger increased RBC production due to lower oxygen levels.
• Diet & Nutrition: Iron, B12, folate, and vitamin C influence RBC production.
• Exercise: Endurance training can lower HCT, while resistance training can raise it.

B. Testosterone Replacement Therapy (TRT) and Hematocrit

One of the most common side effects of Testosterone Replacement Therapy (TRT) is increased erythropoiesis (RBC production), leading to elevated hematocrit.

Why Does TRT Raise Hematocrit?

• Testosterone stimulates erythropoietin (EPO), a hormone that signals bone marrow to produce more RBCs.
• Higher RBCs increase blood viscosity, which can raise blood pressure, cardiovascular risk, and clot formation.
• Older men & those genetically predisposed to high HCT are at greater risk.

4. Managing Hematocrit While on TRT

If you’re on TRT, keeping hematocrit in check is crucial to avoid thickened blood (polycythemia) and cardiovascular issues.

A. Monitoring

• Regular Bloodwork: Every 3-6 months, check:
  • Hematocrit (HCT)
  • Hemoglobin (HGB)
  • Red Blood Cell Count (RBC)
  • Blood Viscosity Markers (Ferritin, Serum Iron, TIBC)
  • Blood Pressure

If HCT exceeds 52-54%, action is necessary.

B. How to Lower Hematocrit on TRT

1. Adjust Testosterone Dosage & Frequency
   • Lowering the dose can reduce erythropoiesis.
   • More frequent, smaller injections (e.g., daily or every other day instead of weekly) can prevent peak spikes that trigger RBC production.
2. Donating Blood (Therapeutic Phlebotomy)
   • Reduces hematocrit quickly by removing RBCs.
   • Whole blood donation every 8-12 weeks can help.
   • If you can’t donate, ask your doctor about therapeutic phlebotomy.
3. Increase Hydration
   • Dehydration falsely elevates HCT.
   • Drink 2-3L of water daily.
   • Electrolytes (e.g., LMNT) help balance hydration.
4. Aspirin (Low Dose)
   • 81mg daily aspirin can reduce clot risk if hematocrit is elevated.
   • Consult a doctor before using it long-term.
5. Cardio & Exercise
   • Aerobic exercise lowers hematocrit by increasing plasma volume.
   • High-intensity workouts can increase RBCs, so balance is key.
6. Supplements to Manage Hematocrit
   • Fish Oil (EPA/DHA): Lowers blood viscosity and reduces inflammation.
   • Turmeric (Curcumin): Anti-inflammatory, improves blood flow.
   • Nattokinase: Natural blood thinner.
   • Grapefruit, Garlic, Vitamin E: Help thin blood naturally.
7. Diet Adjustments
   • Reduce Iron Intake (if high ferritin levels are present)
     • Avoid excessive red meat & iron-rich foods.
     • Avoid iron supplements.
   • Increase citrus fruits (Vitamin C aids iron metabolism).
   • Increase fiber intake to help with iron regulation.
8. Controlling Estrogen
   • High estrogen can contribute to higher RBC production.
   • Ensure estradiol (E2) is within range (use aromatase inhibitors only if necessary).

5. When to Be Concerned?

Symptoms of High Hematocrit (Polycythemia)

• High blood pressure
• Headaches
• Dizziness or blurry vision
• Flushed skin (especially face)
• Fatigue
• Nosebleeds
• Shortness of breath

Dangers of Unmanaged High Hematocrit

• Increased Blood Clot Risk → Stroke, heart attack
• High Blood Pressure
• Thicker Blood (Hyperviscosity Syndrome)
• Increased Risk of Organ Strain (Heart, Lungs, Kidneys)

If HCT consistently exceeds 54%, seek medical intervention.

6. Summary: Key Takeaways

• Hematocrit measures RBC % in blood; normal range for men is 40-50%.
• TRT increases hematocrit due to testosterone-induced RBC production.
• Monitoring HCT levels (every 3-6 months) is essential on TRT.
• To lower hematocrit: Adjust TRT dose, donate blood, stay hydrated, exercise, take supplements, and manage iron intake.
• If HCT > 54%, action is needed to avoid cardiovascular risks.