Assessment of potassium metabolism, using 42K, in cases of myxoedema before and after treatment with thyroxine.

Total Exchangeable Potassium (TEK) was measured in 31 elderly patients admitted to a geriatric assessment unit. The value in control cases ranged between 26 mEq/kg to 45.5 mEq/kg; the mean values for men and women were 35.5 mEq/kg and 28.4 mEq/kg, respectively. The test was repeated after one week in eight cases, the standard deviation between the two estimations ranged from 0.35 to 1.13 with the exception of one case which was 2.55. Estimations were made in six cases of myxoedema, the initial value was low and on treatment rose by 22.6 per cent to 36.4 per cent which coincided with the clinical improvement.