Plasma and Urineosmolality in Untreated Thyroprivic Hypothyroidis: Effect of Eltroxin Therapy

by AD Bhattacharyya, RJ Dash

Journal of Association of Physicians of India 1994 Vol 42 Page 366-8

Plasma and Urine osmolality were determined in 56 thyroprivic hypothyroid patients before and at 2 and 6 months of eltroxin treatment. Normal range of plasma osmolality (Posm) was defined at 95% confidence limits of values obtained from 25 euthyroid healthy controls. Thirty patients (53%) had lower Posm. The mean Posm in 56 hypothyroid patients increased from 283.4 + 2.06 SEM pretreatment, to 295.3+1.5 at 2 months(p<0.001) and 296.5+1.07 at 6 months.

The improvements in Posm from those with lower values (30 patients) were more appreciable: 272.3+1.03 pretreatment, 290.3+1.9 at 2 months (p<0.001 and, 296.16+1.1 at 6 months (p<0.001). Urine osmolality also increased from a normal mean of 477.04+29.64 to 582.48+28.67 at 2 months (p<0.05) an d651.46+28.35 at 6 months (p<0.001) of Eltroxin treatment.

Plasma and urine osmolality correlated positively with the clinical severity of hypothyroid state (plasma T3, T4 & TSH)(p<0.001).

These observations suggested a positive influence of thyroid hormones on plasma and urine osmollality and that plasma and urine osmolality increased with achievement of euthyroid state.