Burr cells or crenated red cells

• Burr cells are crenated red cells, also known as echinocytes. Crenated red cells have changed from a disc shape to spheres covered with short, sharply pointed projections
• artefactual crenation may be due to slow drying of the smear or aging of blood in the tube. Older red cells, whether aged in circulation or in the tube, are more likely to undergo the discocyte-echinocyte transformation than younger red cells.

Crenated cells are usually identified incidentally on a peripheral blood smear. However, their presence may warrant further evaluation in certain populations, including:

• Individuals undergoing routine blood tests with unexplained abnormal findings.
• Patients presenting with symptoms of dehydration, kidney dysfunction, or metabolic imbalances, such as excessive thirst, low urine output, or confusion.
• Individuals with chronic conditions, including diabetes, liver disease, or uraemia, who are at risk for fluid and electrolyte disturbances.
• Patients experiencing anaemia-related symptoms, such as unexplained fatigue, pallor, dizziness, or shortness of breath, where crenation may suggest underlying dehydration or metabolic shifts.

Reference

1. An R, Wipf DO, Minerick AR. Spatially variant red blood cell crenation in alternating current non-uniform fields. Biomicrofluidics. 2014 Mar 5;8(2):021803