[Diurnal dynamics of urinary excretion of potassium during one- and two-shift work].

Four groups of constructive and industry workers--men aged 19-20--were examined. Group 1 and 3 subjects (10 subjects in each group) worked for 1 or 2 years, respectively, in the day shift only. Group 2 (5 subjects) and 4 (10 subjects) subjects worked for 1 or 2 years, respectively, in the day and night shifts, with the shift alternating every week. The day shift was from 8.00 a.m. to 5.00 p.m. and the night shift was from 5.00 p.m. to 1.00 a.m. The test subjects were examined in a hospital on the day following the working week. Group 1, 3 and 4 subjects were examined once (Group 4 after the night shift), and Group 2 subjects twice (after the day and night shifts). Urine was collected every odd hour with a two-hour interval from 7.00 a.m. to 7.00 a.m. of the next day. The day shift in both groups was accompanied by an early increase in potassium excretion. The shift transition was attended by a change of the daily maximum toward later hours. As compared to the one-shift work, the two-shift work increased the amplitude of the diurnal potassium excretion. This can be considered as a stressful effect of the two-shift work. This effect was very distinct after a week of the day-shift work. Therefore, when assessing the physiological effects of the two-shift work, with respect to daily variations in renal potassium excretion, it is necessary to carry out pertinent examinations after the day-shift work.