Normal range: 38.5 – 50 % (higher is better)
Hematocrit measures what percentage of your blood is made up of red blood cells versus plasma. It rises and falls alongside hemoglobin and RBC count. Low hematocrit points to anemia or blood loss. High hematocrit may suggest dehydration, smoking, or a bone marrow condition. Because it is a percentage, hematocrit can shift based on fluid status alone.
Hematocrit isn't sold on its own. It comes in a complete blood count (CBC), about $35. A fuller workup adds Vitamin D ($75), hs-CRP ($69), ApoB ($50), and ApoA1 ($50). You can test Hematocrit and 100 other biomarkers for $190 as part of an Empirical membership.
Empirical is FSA/HSA eligible, so you can pay with pre-tax dollars. Fast for 8-12 hours beforehand for the most accurate lipid and metabolic results, and expect results in days rather than weeks.
Hematocrit measures the percentage of blood volume occupied by red blood cells, indicating oxygen-carrying capacity.
Hematocrit stays relatively flat across adult ages (correlation with age, r = +0.03). Most of the spread in the chart below comes from differences between people rather than from age.
A normal Hematocrit is 38.5 – 50 %. Higher is better.
Low hematocrit has the same causes as low hemoglobin and RBC: iron deficiency, B12 or folate deficiency, chronic disease, blood loss, and bone marrow problems. Overhydration (excess IV fluids) can dilute the reading without actual red cell loss.
High hematocrit is most often from dehydration. Chronic causes include smoking, sleep apnea, living at high altitude, and testosterone or anabolic steroid use. Polycythemia vera, a rare bone marrow disorder, causes persistently elevated hematocrit.
The same dietary and lifestyle factors that support hemoglobin apply here: iron-rich foods, adequate B12 and folate, and staying well-hydrated. If you are dehydrated before a blood draw, hematocrit may look artificially high. Drinking water before your test gives a more accurate baseline.
Hematocrit is most highly correlated with Iron Saturation and Carbon Dioxide. Here are the top biomarkers correlated with Hematocrit, based on 500,000 tests done by Empirical Health.
The percentage shows how strongly two biomarkers move together. A higher number means the relationship is stronger. Green = rises and falls together. Orange = one rises as the other falls.
Hematocrit is drawn at 2,200+ Quest and BioReference patient service centers across the US, so there's usually one within a short drive. Browse the full directory to find the one closest to you.
Test your Hematocrit and 100+ other biomarkers in a single blood draw.
