Hematological Parameters are Altered during Cold Air Exposure

摘要

Whole blood hematocrit (HCT) decreases during multiple exposures to cold air. Tobetter understand this finding, we have analyzed hematological profiles in 27 normal adult men exposed repeatedly to cold air in one of two experimental protocols. Experiment I was a cold air acclimatization study (CAA) conducted with two groups of 8 men in each group before, during, an after 80 separate 30-minute cold (4 C) air exposures. As part of a metabolic study, half of the men received placebo daily (n=8), and the other half received an oral daily maintenance dose of the thyroid hormone triiodothyronine (T3). Blood was analyzed prior to and after every 20 cold exposures. Both groups reacted similarly. When compared with basal conditions, hematocrit (HCT) and erythrocyte counts (RBC) were decreased (p < 0.05); mean corpuscular hemoglobin concentration (MCHC) and plasma volume (PV) were increased with cold exposure (p < 0.05). Hemoglobin (Hb), leukocyte counts (WBC), and mean corpuscular volume (MCV) were unchanged. Experiment II was carried out with 9 military volunteers during extended arctic winter field operations (EAO) in Utah and Alaska. Blood was analyzed prior to and after completion of EAO. A changing hematological profile similar to that in the CAA protocol was found. Hematocrit and RBC were decreased (p < 0.02); MCHC and PV were increased (p < 0.02). Hemoglobin, WBC, and MCV were unchanged. In addition, there was a negative correlation between HCT and the absolute reticulocyte count in this second experiment. It would appear that in instances of cold stress, whether induced or naturally occurring, certain blood cellular element respond in a similar adaptive manner.