SEASONAL ALTERATIONS IN PLASMA BETA-HYDROXYBUTYRATE AND RELATED BIOCHEMICAL PARAMETERS IN THE DESERT TORTOISE (GOPHERUS-AGASSIZII)

beta-Hydroxybutyrate and routine biochemical parameters were determine d on plasma and urine samples obtained from free-ranging desert tortoi ses over a 1-year period. Urea nitrogen varied inversely with total pr otein concentration (P < 0.019); significant azotemia and hypoproteine mia were noted following emergence from hibernation. In summer, elevat ed glucose and cholesterol levels, together with lower sodium, urea ni trogen and urine specific gravity, reflected availability of food and water. Plasma beta-hydroxybutyrate levels significantly (P < 0.004) in creased in the fall (1.92 +/- 0.95 mmol/l), during a period of low rai nfall. Results suggest that plasma beta-hydroxybutyrate may increase i n response to short term energy needs, while protein catabolism plays a greater role in providing fuel during hibernation.