PMID- 1562290 OWN - NLM STAT- MEDLINE DCOM- 19920521 LR - 20131121 IS - 0782-226X (Print) IS - 0782-226X (Linking) VI - 51 IP - 1 DP - 1992 Jan TI - Hematological parameters are altered during cold air exposure. PG - 16-22 AB - Whole blood hematocrit (HCT) decreases during multiple exposures to cold air. To better 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, and after 80 separate 30-minute cold (4 degrees 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) (30 micrograms/day). 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 less than 0.05); mean corpuscular hemoglobin concentration (MCHC) and plasma volume (PV) were increased with cold exposure (p less than 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 less than 0.02); MCHC and PV were increased (p less than 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 elements respond in a similar adaptive manner. FAU - D'Alesandro, M M AU - D'Alesandro MM AD - Thermal Stress Adaptation Program, Naval Medical Research Institute, Bethesda, Maryland. FAU - Reed, H L AU - Reed HL FAU - Lopez, A AU - Lopez A LA - eng PT - Clinical Trial PT - Controlled Clinical Trial PT - Journal Article PT - Research Support, U.S. Gov't, Non-P.H.S. PL - Finland TA - Arctic Med Res JT - Arctic medical research JID - 8602204 RN - 06LU7C9H1V (Triiodothyronine) SB - IM MH - Acclimatization MH - Adult MH - *Blood Cell Count MH - *Cold Climate MH - *Erythrocyte Indices MH - *Hematocrit MH - Humans MH - Male MH - Plasma Volume MH - Triiodothyronine/administration & dosage EDAT- 1992/01/01 00:00 MHDA- 1992/01/01 00:01 CRDT- 1992/01/01 00:00 PHST- 1992/01/01 00:00 [pubmed] PHST- 1992/01/01 00:01 [medline] PHST- 1992/01/01 00:00 [entrez] PST - ppublish SO - Arctic Med Res. 1992 Jan;51(1):16-22.