Table 1. Characteristics of study groups just prior to water deprivationa

CTLHTHT + TP
a HT, hypothyroid rats; CTL, euthyroid rats; HT + T, hypothyroid rats replaced with L-thyroxine.
b P < 0.001 HT versus CTL; P < 0.001 HT versus HT + T.
Body weight at start of study (g)198 ± 5190 ± 4188 ± 4NS
Body weight after treatment (g)254 ± 6241 ± 5242 ± 5NS
Water intake (ml/d)25 ± 120 ± 221 ± 1NS
Urine output (ml/d)14 ± 114 ± 112 ± 1NS
Urine osmolality (mOsm/kg H2O)1627 ± 921529 ± 691607 ± 159NS
Dietary sodium intake (mg/d)56 ± 156 ± 156 ± 1NS
Serum osmolality (mOsm/kg H2O)299 ± 5291 ± 5298 ± 4NS
Serum creatinine (mg/dl)0.62 ± 0.060.54 ± 0.040.48 ± 0.02NS
24-h creatinine clearance (ml/min)1.22 ± 0.101.12 ± 0.101.20 ± 0.03NS
Serum calcium (mg/dl)9.7 ± 0.39.7 ± 0.19.2 ± 0.1NS
Serum magnesium (mEq/L)2.0 ± 0.11.9 ± 0.11.9 ± 0.1NS
Fractional excretion of sodium (%)0.48 ± 0.190.64 ± 0.070.53 ± 0.04NS
UureaV (mg/d)236 ± 23215 ± 10240 ± 28NS
UosmV (mOsm/d)19 ± 321 ± 114 ± 4NS
Serum free thyroxine (ng/dl)1.7 ± 0.1< 0.42.7 ± 0.1b