La proporción del volumen sanguíneo ocupada por glóbulos rojos. Disminuye en anemia y pérdida de sangre, aumenta con deshidratación e hipoxia.
Otros nombres:Hematocrit, packed cell volume (PCV)Sección:Células sanguíneas
Actualizado: 29 de agosto de 2026·Equipo editorial de MedProtect Información de referencia — no es un diagnóstico ni una prescripción
En resumenHematocrit is the percentage of blood made up of red cells. Typical adult values are 37–48% for men and 34–43% for women; newborns run higher at 45–61%. The percentage moves with both the red cell mass and the plasma volume, which is why dehydration raises it and pregnancy lowers it.
Valores de referencia
Grupo
Valor de referencia
Hombres adultos
37–48%
Mujeres adultas
34–43%
Recién nacidos
45–61%
Lactantes
32–42%
Common reference values from the MedlinePlus Medical Encyclopedia. Intervals vary between laboratories and with smoking and altitude — the range on the report applies.
Compruebe su valor
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
A rough comparison with a typical range, not a diagnosis. Reference ranges vary between laboratories — check the range on your own report and let a clinician interpret the result.
Qué es este marcador
If a tube of blood is spun down, the red cells pack at the bottom and the straw-colored plasma stays on top. Hematocrit is simply the height of the red layer as a percentage of the whole column — a result of 42% means 42% of the blood volume is red cells.
The measurement depends on both the number and the size of red cells, so it moves together with the RBC count and hemoglobin. The three lines are reported together in the CBC and are read as a set: anemia shows up in all of them, and their proportions hint at the cause.
Because hematocrit is a ratio, it is sensitive to plasma volume as much as to red cells. Dehydration concentrates the blood and raises the percentage; pregnancy and overhydration dilute it and lower the percentage without any change in the actual number of cells.
Providers order the test — almost always within a CBC — for fatigue, suspected bleeding, chronic kidney disease, before and after surgery, during pregnancy, and to monitor treatments that can suppress the bone marrow.
Cuando está elevado
DeshidrataciónThe most common cause: with less plasma water the same red cells take up a larger share of the volume. Severe diarrhea is the textbook example.
Chronic low oxygenLung disease, congenital heart disease, and cor pulmonale drive red cell production up, and the percentage follows.
TabaquismoCarbon monoxide exposure reduces oxygen delivery and the body compensates with more red cells.
Polycythemia veraA marrow disorder that overproduces red cells; a persistently high hematocrit without another explanation leads here.
Kidney tumoresRenal cell carcinoma and some cysts secrete erythropoietin and push red cell production up.
AltitudeThe percentage climbs naturally over the first weeks at high altitude and drifts back after descent.
Cuando está bajo
SangradoRecent injury or chronic hidden blood loss removes red cells faster than they are replaced.
Anemia of any causeToo few or too small red cells — iron, B12, folate, B6, or copper deficiency among the causes — lower the red cell share.
Bone marrow suppressionLeukemia, other cancers, medicine toxicity, radiation, and infection can all slow the marrow's output of new red cells.
Enfermedad renal crónicaLess erythropoietin means a weaker production signal and a gradually falling hematocrit.
EmbarazoPlasma volume expands faster than red cell mass, so the percentage dips — a normal physiological change that is still monitored.
OverhydrationExcess fluid dilutes the blood; the percentage falls while the actual cell count is unchanged.
Qué puede alterar el resultado
Estos factores pueden alterar el valor sin ninguna enfermedad — vale la pena considerarlos antes de repetir la prueba:
Hydration on the test dayEmbarazoTabaquismoAltitude of residenceRecent bleeding or transfusionMedicines affecting the marrow
Cómo prepararse
No special preparation is needed for a hematocrit test. It is one line of the CBC; fasting requirements would come only from other tests in the same draw. Because hydration shifts the percentage, the circumstances of the day — a stomach bug, a long flight — are worth mentioning.
Cuándo tiene sentido repetir la prueba
An off-range percentage is commonly rechecked after rehydration or recovery from the provoking event. In anemia treatment or polycythemia monitoring the test is repeated on the treating provider's schedule to track the trend.
Quién suele revisar este resultado
Un resultado fuera del rango de referencia suele ser revisado por:your GP or primary care doctor; a hematologist if a blood disorder is suspected. Traiga su informe de laboratorio y cualquier resultado anterior a la cita.
Nombres usados en los informes de laboratorio
Su informe puede usar cualquiera de estos nombres: HCTHctPacked cell volumePCV
Unidades
Medido en:%
%=L/L
L/L = % × 0.01 (1% = 0.01 L/L)
¿Varios marcadores en su informe?
See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.
Hemoglobin measures the oxygen-carrying protein concentration; hematocrit measures the volume share of red cells. As a rough rule the hematocrit percentage is about three times the hemoglobin number, and the two move together.
Why is my hematocrit high when I feel fine?
The commonest benign reason is dehydration on the day of the draw. Smoking and altitude do the same. A repeat test after normal drinking usually settles the question.
Does hematocrit change during pregnancy?
Yes — plasma volume grows faster than red cell mass, so the percentage drops. Prenatal CBCs track it to separate this normal dilution from true iron-deficiency anemia.
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