Blood Thickness Gauge
If you let a tube of blood sit, the red cells settle to the bottom. Hematocrit is the percentage of your blood that's red cells versus liquid plasma. It tells you how thick or thin your blood is running.
What is Hematocrit?
Hematocrit measures the proportion of blood volume occupied by red blood cells, expressed as a percentage. It moves in lockstep with hemoglobin and RBC count—if one is off, the others usually are too.
↑ What High Hematocrit Means
Your blood has a higher-than-normal proportion of red cells. It's thicker, flows slower, and your heart has to work harder to pump it. Think of it like motor oil that's too viscous.
Common symptoms:
Headaches · Blurred vision · Flushing or redness · Itching · Blood clot symptoms
↓ What Low Hematocrit Means
Your blood is thinner than ideal—too much liquid relative to red cells. You're not carrying enough oxygen per pump of blood.
Common symptoms:
Fatigue and weakness · Pale skin · Shortness of breath · Rapid heartbeat · Dizziness
Why It Matters
When normal:
Proper blood viscosity for efficient circulation
Adequate oxygen-carrying capacity
Healthy blood pressure regulation
Good exercise performance
Risks if abnormal:
Increased clot and stroke risk when too high
Anemia symptoms when too low
Heart strain from pumping thick blood
Poor wound healing
What Can Cause Abnormal Levels?
Dehydration
60% likelyLess plasma = higher concentration of red cells. Most common cause of mildly elevated hematocrit.
Iron Deficiency Anemia
55% likelyFewer red cells = lower hematocrit percentage.
Chronic Lung Disease
Low oxygen triggers your body to produce more red cells as compensation.
Polycythemia Vera
Rare bone marrow disorder causing overproduction of red cells.
What You Can Do
Hydrate adequately: 2-3L water daily
Impact: Normalizes plasma volume \u00B7 Timeline: 1-3 days
Iron-rich diet if low: liver, red meat, lentils
Impact: Supports red cell production \u00B7 Timeline: 4-8 weeks
If lifestyle changes aren't enough:
Iron supplementation if deficient
Impact: Restores hematocrit over time \u00B7 Timeline: 8-12 weeks
Regular moderate exercise
Impact: Improves blood flow efficiency \u00B7 Timeline: 4-8 weeks
Recommended retest: 3 months
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