J Med Assoc Thai 1999; 82 (7):690

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Potassium Needed for Maintaining its Balance in Healthy Male Subjects Residing in an Area of Low Potassium Intake and with a High Environmental Temperature
Sriboonlue P Mail, Prasongwatana V , Suwantrai S , Bovornpadungkitti S , Tungsanga K , Tosukhowong P

Low potassium (K) intake and high prevalence of hypokalemia and hypokaliuria among
rural dewellers in the northeast region of Thailand have been repeatedly reported and they were
speculated to be in a state of low K status. In this communication we studied K balance of 10 rural
(R) and 5 urban (U) male subjects in this region during a 10-day period of semi-free-living and eating
group-selected diets. While K in intake, 24- h urine and feces were measured daily in all subjects,
the direct measurement of K lost in sweat was made only in one subject coded R3. These parameters
were then used to calculate the K balance. The results showed that mean K intakes were 1731±138
and 1839±145 mg/day for R and U subjects, respectively. Their mean K balances, calculated by
subtracting the K excretions in 24-h urine (721±129 mg/day for Rand 919±186 mg/day for U) and
in feces (148±25 mg/day for Rand 164±21 mg/day for U) from intakes, were +860±140 and +756±
222 mg/day for Rand U, respectively. In the subject R3, his mean K balances without and with subtracting
the sweat K excretion (451±57 mg/day), were +847±373 and +396±344 mg/day, respectively.
Regression of K balance versus intake indicated that R and U subjects needed K of 832
and 884 mg/day to stay in balance. Since the study was performed during the hot season (average
temperature=35.2±2.0°C at 3 pm) and sweating was clearly observed (estimated sweat volume per
day was 1927±420 ml for R and 1759±408 ml for U), therefore, K balance calculated without sweat
K was overestimated. This was apparently seen in the subject R3 where he actually needed K of
1203 mg/day, instead of 814 mg/day calculated without sweat K, to stay in balance. The similarities
in K balance data among the two groups suggested they both had the same food habit and
K status. Our results indicate that any calculation for the levels of dietary K, or probably also for
other minerals, to achieve the balance could be underestimated if loss via sweat is not taken into consideration.
Key word : Potassium Intake, Potassium Balance, Urinary Potassium, Fecal Potassium, Sweat Potassium

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