Know Your Hematocrit before Surgery

Robert W. Griffith, MD

If you're over 65, you might want to know a bit more about your hematocrit. It's the percentage, by volume, of the blood that consists of red blood cells. For example, a hematocrit of 25% means that there are 25 mL of red blood cells in 100 mL of blood. The normal hematocrit for adult men is 42-54%, and for adult women 39-46%.

A low hematocrit, signifying anemia, may be due to loss of blood (e.g. injury, surgery, intestinal bleeding), nutritional deficiency (iron, vitamin B12 or folate), or bone marrow replacement by cancer, or suppression by drugs (e.g. chemotherapy). A raised hematocrit occurs in people living at high altitudes, chronic smokers, and a rare bone marrow disease called polycythemia rubra vera, when too many red blood cells are produced; it can also occur in severe dehydration.

A report in the Journal of the American Medical Association shows that, in older people, preoperative hematocrit levels outside the normal range are associated with higher mortality after surgery. Data from 310,300 mostly male patients over 65 who underwent major non-cardiac surgery showed a 30-day mortality for the entire collective of 3.9%. Patients with a preoperative hematocrit below 39.0% or above 54.0% had a 1.6% increase in their mortality risk for each percentage-point outside from this range.

This finding suggests surgeons and anesthetists should pay attention to the preoperative hematocrit in older persons, and postpone non-urgent surgery until those outside the normal range can be appropriately corrected.

Source
HealthandAge Blog

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