CHANGES IN SPECIFIC GRAVITY AND OUTPUT OF URINE IN TIME LAPSE

Evaluation with Continued Monitoring for 24 Hours

Abstract

The specific gravity of urine, urinary output and running average of hourly urine production were determined in 3 volunteers for a period of 24 consecutive hours. A Terumo's urine specific gravity monitor, urinary output monitor, and 12 channel dotting recorder were used for the determination. Three volunteers with normal hepatic and renal functions in terms of blood biochemistry and with no adverse problem in their cardiopulmonary functions or in their metabolic functions were the subjects of the present study. The meals provided were a general diet. The water content of each meal was 1400ml, and as a rule, each of the volunteers was requested to consume the whole amount of the food each time. Ingestion of water other than from the meals was restricted only to water taken ad libitum and not any other beverage, with no restriction of water drinking (water free condition). Any juice or liquid which has a diuretic effect was avoided and fruit juice or its component also was excluded. No drug was taken while the test was going on, and the smokers were prohibited to smoke during the test.
Analysis of the data obtained by the sequential determinations revealed that the magnitude of the variation of the specific gravity of urine was larger in the young than in the old. The variation was more rhythmical in the young than in the old. The ultradian rhythm of urine excretion viewed from the running average of hourly urine production of urinary output was at an interval of 10-80 minutes, but with no appreciable difference with age. The check of the circadian rhythm of urinary excretion revealed a rhythm proper for each volunteer could be observed even in the water free condition. All of the volunteers evaluated in the present study were healthy. The marker to be used as the criterion for the renal functions was found within the normal range. However, a circadian rhythm of urinary excretion suspected as the reversal of daytime and night was observed in one volunteer. Whether this was pathological or within the normal range should be investigated by future studies. Thus, it was found out each one has his own circadian rhythm of urine excretion. The check of this rhythm seems to be useful and interesting as a method for testing renal functions.