Crenated RBC's

Function

Crenated Red Blood Cells (RBCs), also known as echinocytes or burr cells, are erythrocytes that have lost their smooth, biconcave shape and developed small, evenly spaced thorny projections across their surface. In a physiological context, RBCs must maintain a specific surface-area-to-volume ratio to remain flexible enough to pass through tiny capillaries. Crenation occurs when the cell is placed in a hypertonic environment, causing water to leave the cell via osmosis, resulting in a shriveled appearance.

Why it is Ordered

Identifying crenated RBCs is rarely the primary goal of a blood test but is often noted during a peripheral blood smear examination. This observation is critical for:

• Distinguishing Artifact from Pathology: Determining if the shape is due to improper slide preparation (glass effect) or a systemic medical condition.
• Renal Assessment: High numbers of echinocytes are frequently associated with uremia or acute kidney injury.
• Metabolic Screening: Evaluating potential electrolyte imbalances or liver dysfunction.

Associated Conditions

Several clinical states are linked to the presence of crenated RBCs:

• Uremia: Common in chronic kidney disease where metabolic waste products alter the RBC membrane.
• Liver Disease: Particularly in cases where cholesterol or lipid metabolism is disrupted.
• Hypophosphatemia: Low phosphorus levels can deplete ATP, affecting the cell membrane's structural integrity.
• Dehydration: Severe hypertonic dehydration can lead to systemic cell crenation.
• Artifact: Prolonged storage of blood in EDTA tubes or high pH from glass slides often causes 'pseudo-crenation'.