Differential Diagnosis: Erythrocytosis

Following are differential diagnoses for patients presented with erythrocytosis.

• Absolute erythrocytosis (ie, increased RBC mass)

  • Breed-related erythrocytosis (eg, sight hounds [eg, greyhounds], dachshunds)

  • Primary erythrocytosis (ie, polycythemia vera)

  • Secondary erythrocytosis

• Appropriate (response to systemic hypoxia or increased hemoglobin affinity) 

  • Carbon monoxide poisoning 

  • Congenital heart defect involving right-to-left shunting (eg, ventricular septal defect with Eisenmenger’s syndrome, tetralogy of Fallot, reverse patent ductus arteriosus)

  • High altitude

  • Respiratory disease (eg, brachycephalic obstructive airway syndrome, chronic pulmonary disease)

  • Severe obesity

• Inappropriate (absence of systemic hypoxia)

  • Acromegaly

  • Erythropoietin-producing tumors (eg, splenic hemangiosarcoma, cecal leiomyosarcoma, hepatic tumors)

  • Hyperadrenocorticism

  • Hyperthyroidism

  • Local renal hypoxia (eg, pyelonephritis, leptospirosis, renal tumors [eg, carcinoma, sarcoma, lymphoma])

• Relative erythrocytosis (common)

  • Dehydration

  • Splenic contraction (eg, with exercise, fear, or excitement)