Sk. Arthur et al., A STUDY OF NEPHRON FUNCTION IN NORMAL TROPICAL RESIDENTS USING THE CREATININE AND LITHIUM CLEARANCES, International journal of biometeorology, 41(1), 1997, pp. 40-43
The kidney bears the brunt of the demands of a tropical climate for wa
ter and electrolyte homeostasis. We hypothesised that a tropical clima
te may cause adaptive changes in the entire organism leading to altere
d renal function in our subjects. Hence renal function data for reside
nts of a temperate climate may not be applicable to tropical residents
. We therefore sought to elucidate renal function in subjects residing
in a tropical climate. We used lithium clearance, C-Li, a non-invasiv
e tool for assessing proximal tubular function in humans, and endogeno
us creatinine clearance, C-Cr, to estimate proximal tubular function a
nd glomerular function, respectively, in our subjects. We did this in
order to establish whether or not nephron function in our subjects dif
fers from that for residents of a temperate climate. Nineteen male and
12 female Ghanaian subjects aged between 15 and 48 years were studied
. The estimated G(Cr) was 117.3+/-6.6 ml/min for male subjects and 97/-6.4 ml/min for female subjects. C-Li was 20.3+/-1.6 ml/min for male
and 19.1+/-0.4 ml/min for female subjects, respectively. The estimated
absolute reabsorption rate of fluid of proximal tubules was 97.0+/-6.
0 ml/min for males and 78.1+/-6.0 ml/min for females. The percentage p
roximal fluid reabsorption for male and female subjects was 81.2+/-1.4
and 79.5+/-1.6, respectively. The differences between male and female
values (mean+/-SEM) were not statistically significant. The data sugg
est that the proximal tubule in residents of a tropical climate may re
absorb more fluid compared to that in residents of a temperate climate
. Our values for proximal tubular reabsorption are higher than those r
eported for residents of a temperature climate. Our estimate of glomer
ular filtration, however, is similar to published data for Caucasians.
The difference in proximal tubular function may reflect possible rena
l adaptation to a hot, humid climate. We conclude that renal function
of tropical residents differs from that of residents of a temperate cl
imate. This difference may be due to renal adaptation to the hot, trop
ical climate.