What can cause elevated Red Blood Cells (RBCs)?

From the Guidelines

Elevated red blood cell (RBC) counts can be caused by several conditions, including polycythemia vera, dehydration, high altitude, lung diseases like COPD, certain medications, smoking, kidney diseases, tumors, and genetic disorders like hemoglobinopathies. These conditions can lead to an increase in RBC production, either as a compensatory response to hypoxia or due to abnormal production of erythropoietin [ 1 ].

Common Causes of Elevated RBCs

Some common causes of elevated RBCs include:

• Dehydration, which concentrates blood components
• Living at high altitudes, where the body produces more RBCs to compensate for lower oxygen levels
• Lung diseases like COPD that reduce oxygen saturation
• Certain medications such as testosterone or erythropoietin that can stimulate RBC production
• Smoking, which increases carbon monoxide in the blood, triggering more RBC production
• Kidney diseases or tumors that may inappropriately increase erythropoietin production
• Genetic disorders like certain hemoglobinopathies that can lead to elevated RBC counts

Importance of Evaluation

If you have elevated RBCs, it's essential to consult with a healthcare provider for proper evaluation, which typically includes a complete blood count, oxygen saturation measurement, and possibly additional tests to determine the underlying cause [ 1 ]. This evaluation is crucial to identify the underlying cause of elevated RBCs and to guide appropriate management.

Management of Elevated RBCs

Management of elevated RBCs depends on the underlying cause. In some cases, therapeutic phlebotomy may be necessary to reduce blood viscosity and relieve symptoms of hyperviscosity [ 1 ]. However, repetitive phlebotomies can deplete iron stores and lead to iron deficiency, which can worsen oxygen delivery to tissues. Therefore, iron supplementation may be necessary to maintain adequate iron levels.

From the Research

Causes of Elevated Red Blood Cells (RBCs)

Elevated RBCs can be caused by various factors, including:

• Polycythemia vera (PV), a myeloproliferative neoplasm characterized by an increased red blood cell mass and increased risk of thrombosis, as discussed in 2
• Secondary causes of erythrocytosis, such as tobacco smoking or sleep apnea, as mentioned in 2
• Nonalcoholic fatty liver disease (NAFLD), where elevated RBC count is associated with an increased risk of NAFLD incidence and progression, as found in 3
• Genetic predisposition for increased red blood cell distribution width (RDW), which is an early risk factor for cardiovascular and renal comorbidities, as reported in 4

Associated Conditions

Elevated RBCs have been linked to several conditions, including:

• Thrombosis, as patients with PV are at increased risk of arterial and venous thrombosis, as discussed in 2
• Hemostasis and thrombosis, where RBCs play a biologically and clinically important role, as summarized in 5
• Cardiovascular diseases, where increased RDW is prominently associated with a variety of illnesses, as mentioned in 4
• Renal comorbidities, where genetic predisposition for increased RDW is an early risk factor, as found in 4

Physiological Mechanisms

The physiological mechanisms underlying elevated RBCs involve:

• The ability of RBCs to carry O2 and release vasodilator compounds, such as ATP and NO, in response to tissue oxygenation, as discussed in 6
• The role of RBCs in vascular homoeostasis, focusing on the importance of the NO pathway alterations in cardiovascular diseases, as reviewed in 6