SHORT REPORTS
Stimulated sweating in chronic renal failureBr Med J. 1978 July 15; 2(6131): 172–173.
Concentrations of urea and potassium in the sweat of normal subjects
and patients with chronic renal failure (CRF) are higher than serum
concentrations.'1 Water loss from the skin may exceed two litres per
hour in hot environments.2 4 It would therefore be interesting to
examine the extent to which stimulated sweating in patients with CRF
could compensate for loss of renal function. We describe a patient on
chronic intermittent haemodialysis who was used to taking sauna
baths. Serum concentrations of urea and potassium were low and
weight gain between haemodialysis sessions was small compared with
those of other patients undergoing intermittent haemodialysis. Losses
of urea, potassium, and water in sauna and hot baths) were measured
to investigate whether they could account for the observed low serum
concentrations of these substances and for the stable fluid balance in
this patient.
Patient, methods, and results
A 52-year-old anuric man started to take sauna baths three times a week
on days when he was not undergoing dialysis six months before our study.
Before the sauna baths the patient took a lukewarm shower and brushed his
skin to remove formerly excreted solids. The air temperature in the sauna
was 70 C, and he bathed for one to two hours. After each sauna bath his
body weight decreased by 1 5-2 kg. During the study the sweat that dripped
from his bended head while in the sauna was collected in 20-ml samples, and
total losses of urea and potassium were calculated from weight loss and
sweat concentrations. The patient was also studied in hot water baths of
42-C.5 He was immersed in water up to his neck in an impermeable plastic
bag, which contained 20 litres of distilled water. Fluid from the bag was
sampled before and after the baths and duplicate 1-litre portions were
concentrated tenfold by distillation. This permitted us to calculate more
accurately the total loss of urea and potassium than in the sauna bath.
The figure shows predialysis serum concentrations of urea and potassium
in the patient and in 16 controls on chronic intermittent haemodialvsis.
Results were corrected for differences in dietary intake related to body
weight. After six months serum urea and potassium concentrations were
significantly lower in the patient than in the controls (P< 0 001; t-test). The
sweat to serum urea ratio was 2 0 in two sauna baths and 1-8 in two hot water
baths. Sweat to serum potassium ratio was 2 5 for both sauna and hot water
baths. Sweat rates in sauna and hot water baths were 21 and 33 mllmin
respectively. Urea clearances in hot water baths were therefore higher than
in sauna baths-56 and 40 ml min respectively. Calculated losses of urea and
potassium in sweat were 43 and 12 mmol h (2 6 g 'h and 12 mEq, h) compared
with 117 and 20 mmol/h (7-0 gHh and 20 mEq h) by haemodialysis. Total
excretion of urea and potassium in sweat averaged 215 and 60 mmol/week
(12 9 g/week and 60 mEq week) respectively, which amounted to 19 11 and
3000 of the total quantity removed by haemodialysis. These figures fully
explain the observed falls in serum concentrations of urea and potassium of
23 0, and 35 (, respectively.
Comment
These findings indicate that stimulated sweating can be used as a
valuable adjunct to chronic intermittent haemodialysis. In our patient
a 30-minute hot water bath every day was as effective as a two-hour
sauna bath three times a week. In patients with CRF control of fluid
BRITISH MEDICAL JOURNAL 15 JULY 1978 173
Serum urea Serum potassium
40
8-0
30
6-0
-E6 20 E ~2~3~~~~~~~~~0
4*0
10
_______ 1 _______2.0
Before After Before After
Serum urea and potassium concentrations in patient
with CRF before (e) and six months after ( o) period
when he took sauna baths three times a week. His diet
contained 55 g protein, 50 mmol potassium, and 800 ml
fluid before and 60 g protein, 90 mmol potassium, and
a free fluid intake after six months. Mean results (+ SD)
(n -14) are compared with values in 16 control subjects
(n= 140; shaded area). Patients who needed polysterene
sulphonate to control serum potassium were not
included. All values were measured before dialysis and
were converted to 70 kg of body weight, 100 g daily
protein intake, and 70 mmol potassium intake.
Conversion: SI to traditional units-Urea: 1 mmol/l
6 mg/100 ml. Potassium: 1 mmol/l- 1 mEq/l.
balance, uraemia, and hyperkalaemia can be facilitated by this mode
of treatment, which might obviate the need for strict dietary regulations
and thereby improve quality of life in these patients.
We thank Professor J de Graeff and Dr M A D H Schalekamp for their
advice and criticism.
IDittmer, D S, (editor), Blood and Other Body Fluids. Federation of the
American Society for Experimental Biology, 1961.
2 Schwarts, I L, in Mineral Metabolism, ed C L Comar and F Bromer,
part I, section A, p 346. New York, Academic Press, 1960.
3 Snyder, D, and Merrill, J P, Transactions of the American Society for
Artificial Internal Organs, 1966, 12, 188.
4Kuno, Y, Human Perspiration. Springfield, Illinois, Thomas, 1956.
5Fujishima, K, and Kosake, M, Nagoya Medical Journal, 1971, 17-I, 25.
(Accepted 30 March 1978)
Department of Internal Medicine I, University Hospital, Erasmus
University, Rotterdam
A J MAN IN 'T VELD, MD, medical registrar
Department of Internal Medicine, Division of Nephrology, University
Hospital, Leiden
J H VAN MAANEN, MD, PHD, medical registrar
I M SCHICHT, MD, consultant physician
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