Buffy Coat on Centrifugation of Blood

Buffy coat on centrifugation of blood reflects:

Correct Answer: Both WBC & Platelets

When blood is centrifuged, it separates into three distinct layers. The buffy coat is the thin middle layer (interface) between plasma and RBCs that contains both WBCs (leukocytes) and platelets (thrombocytes).

Blood Layers After Centrifugation

• Upper layer (55%): Plasma (straw-yellow colored) — contains water, proteins, electrolytes, hormones, etc.
• Middle layer / Interface / Buffy coat (<1%): WBCs + Platelets — thin white/grayish band.
• Lower layer (45%): Erythrocytes (RBCs) — densest, settle at bottom; the percentage of this layer = PCV (Packed Cell Volume) / Hematocrit.

Clinical Significance of Buffy Coat

• A thicker than normal buffy coat suggests leukocytosis (increased WBC count) — seen in bacterial infections, leukemia.
• Microhematocrit centrifugation of blood is used to estimate PCV and also allows morphological examination of buffy coat for blood parasites (e.g., Trypanosoma, Anaplasma) in a buffy coat smear.