Body Composition: Studies in the Human Being by the Dilution Principle

The assay of mixtures of sodium-24 and potassium-42 in clinical tracer studies; with particular reference to the measurement of exchangeable sodium and potassium

1. Combinations of different counting systems have been investigated for their efficiency in assaying mixtures of 24Na and 42K. The advantages of a combination of thin and thick walled liquid G.M. counter tubes of the Veall pattern are described. Physical methods are unreliable when only a small proportion of the counts is derived from one isotope.

2. The separation of potassium by precipitation with sodium tetraphenylboron is described. Methods dependent on chemical separation are reliable even when 42K makes only a small contribution to the counting rate of a mixture.

3. The application of these methods to the simultaneous measurement of exchangeable sodium and potassium is discussed and a rapid method for carrying out these measurements is described.

Pathophysiology of rheumatic fever: alterations in the Na24 space and in the exchangeable sodium and potassium contents

Radioisotopic technics were used to explore physiologic aberrations that may characterize individuals with acute rheumatic fever. No significant changes were noted in serial measurements of the blood volume or serum sodium and potassium concentrations. Most of the individuals with severe disease showed an initial value for radiosodium space of more than 330 ml./Kg. of body weight, with no evidence of edema. The exchangeable sodium content of the body correlated well with the radiosodium space. These changes are difficult to explain solely on the basis of extracellular edema, and are interpreted as suggesting that the intracellular content of sodium or that in bone is increased during acute rheumatic fever. An intracellular increase in sodium may be due to an alteration in the permeability of cell membrane induced by an immune mechanism.

Effect of prolonged steroid therapy for rheumatic fever on the exchangeable potassium content and body weight

Serial measurements of the body weight and exchangeable potassium content were made in 13 children with acute rheumatic fever who were being treated with large doses of corticotropin or cortisone. In 8 subjects the clinical signs of hyperadrenalism developed. Seven of the 13 subjects showed at least a 20 per cent increase in body weight, which could not be explained on the basis of changes in the body's exchangeable potassium content. This weight gain is thought to be due to an increase in total body fat.

Studies in surgical endocrinology. I. The urinary excretion of 17-hydroxycorticoids, and associated metabolic changes, in cases of soft tissue trauma of varying severity and in bone trauma

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