Polycythemia

• A disorder characterized by excessive red blood cell production.
• Primary Cause: Polycythemia vera, a bone marrow disorder.
• Secondary Causes: Chronic hypoxia due to lung disease or living at high altitude.

Dehydration

• Reduced plasma volume can concentrate red blood cells.
• This leads to an increased hemoglobin measurement.

Less Common Compensatory Responses

• Certain autoimmune lung disorders or infections compromising oxygen uptake may trigger compensatory mechanisms, raising hemoglobin levels.

Life-Phase Considerations

• Adults:
  Elevated levels can increase blood viscosity and heighten cardiovascular risk.
• Children/Adolescents:
  Normal reference ranges differ.
  Slight variations should be interpreted in the context of age and growth.

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Anemia

• Causes:

• Iron deficiency
• Vitamin B12 or folate deficiency
• Chronic disease, including autoimmune or inflammatory processes

Blood Loss

• Can result from:

• Trauma
• Gastrointestinal bleeding
• Hemolytic processes, some of which may be immune-mediated (e.g., autoimmune hemolytic anemia)

Infections

• Severe or chronic infections may lead to anemia of inflammation.

Age Considerations

• Newborns and Young Children:
  
  • Different normal ranges apply.
  • Iron deficiency anemia is especially common in growing children.
• Elderly:

• Anemia can contribute to frailty and may be multifactorial.

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