Diurnal Variations in Extracellular Fluid Volume in Man Detected by Constant Infusion Technique

Abstract

To detect any possible diurnal variations in the extracellular fluid volume, Inutest^R was used as the indicator compound administered by constant infusion. In 5 patients a mean of 98.5% of the infused amount of Inutest was recovered in the urine. Serial determinations of the apparent distribution volume for Inutest performed throughout one day resulted in an average value of 12.4 litres for this volume, with an average decrease of 1.6 litres around noon and return to the original value in the afternoon.

Key Words:

• Constant infusion technique
• extracellular fluid volume
• inutest