What Are the Causes of a High Hematocrit Level?

By Staff WriterLast Updated Mar 31, 2020 12:07:44 PM ET

Potential causes of a high hematocrit level include dehydration, smoking, living at high altitudes, lung disease, congenital heart disease, polycythemia vera or a erythropoetin-producing tumor in the kidney. Dehydration is the most common cause, and when there is enough fluid intake, the hematocrit returns to normal levels.