Relationship Between Circulating Red Cell Volume and Endogenous Thyroxine in Sheep. ∗

Summary

Radiochemical procedures with 31 castrated male sheep employed to investigate relationships between thyroxine degradation rate and total red cell volume (RCV) permitted procurement of accurate and dependable results without use of substitution therapy. The significant relationship (P< 0.01) between degradation and RCV in these intact animals, under physiological conditions and independent of body weight, would suggest environmental factors to affect red cells through the thyroid axis. The nature and mechanisms of these relationships, though considered speculative, were discussed.