AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 1 114-R119, Copyright © 1984 by American Physiological Society
Effect of iron-deficiency anemia on hormone levels and thermoregulation during cold exposure
J. Beard, W. Green, L. Miller and C. Finch
When exposed to an ambient temperature of 4 degrees C, iron-deficient
anemic rats become hypothermic. This lesion is related more to anemia than
to tissue iron deficiency, since exchange transfusion to hematocrits over
25 restored normal thermoregulatory performance. Likewise poor cold
responses were induced in control rats by transfusion to low hematocrits.
Cold sensitivity in all anemic animals was paralleled by poor thyroid
responses: there was a significant positive correlation between hematocrit
and percent rise in triiodothyronine (r = 0.63) and thyroxine (r = 0.53)
during 6 h at 4 degrees C. Basal levels of thyroid-stimulating hormone
(TSH) were similar in control and iron-deficient animals: after cold
exposure, TSH rose to higher levels in those animals with hematocrits over
25 than in those with lower hematocrits. Diminished O2 delivery to tissues
responsible for heat production is probably a major component of the cold
sensitivity of anemic rats. The novel finding that thyroid hormone
responses are compromised by anemia implies effects on hormonal regulation
that may also contribute to this functional lesion.
