Acute Versus Chronic Blood Loss Hematology Review 313
ACUTE BLOOD LOSS CHRONIC BLOOD LOSS
Definition Rapid loss of >20% blood volume. Loss of small amounts of blood over extended period of time
RBCs Normocytic, normochromic. May be transient Microcytic, hypochromic (due to iron deficiency)
macrocytosis when ↑retics reach circulation.
WBCs ↑(up to 35 × 10^9 /L) with shift to left for about Normal
2–4 days.
Retics ↑in 3–5 days. Peak around 10 days. Normal or slightly ↑
HGB/HCT Steady during 1st few hr due to vasoconstriction & ↓
other compensatory mechanisms. Can be 48–72 hr
before full extent of hemorrhage is evident (after
fluid from extravascular spaces moves into circulation
to expand volume).
Other Immediate fall in PLT, followed by ↑within 1 hr. ↓serum iron & ferritin