pseudopolychthemia

Pseudopolycythemia, also known as relative polycythemia or Gaisböck's syndrome, is a condition characterized by an elevated hematocrit, hemoglobin, and red blood cell count, but without a true increase in red blood cell mass. This means the concentration of red blood cells in the blood appears higher than normal due to a decrease in plasma volume. It is distinct from polycythemia vera, a myeloproliferative neoplasm.

The primary cause of pseudopolycythemia is dehydration. When the body loses fluid, the plasma volume shrinks, making the remaining red blood cells more concentrated. This can occur due to insufficient fluid intake, excessive sweating, vomiting, diarrhea, or the use of certain medications like diuretics. Other contributing factors can include smoking, which can lead to chronic mild dehydration and increased erythropoietin levels, and sometimes stress.

Diagnosis typically involves measuring the hematocrit, hemoglobin, and red blood cell count. If these are elevated, further tests are performed to differentiate it from true polycythemia. This may include measuring red blood cell mass, assessing plasma volume, and evaluating for underlying causes of dehydration or other contributing factors.

Treatment for pseudopolycythemia focuses on addressing the underlying cause. The most common and effective treatment is rehydration. Ensuring adequate fluid intake can restore normal plasma volume and lower the apparent hematocrit. If dehydration is severe, intravenous fluids may be necessary. In cases linked to smoking, cessation is recommended. Pseudopolycythemia generally resolves once the cause is corrected and does not typically lead to long-term complications.