The influence of body posture on lithium clearance.
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The influence of body posture on lithium clearance. / Kamper, A L; Strandgaard, S; Holstein-Rathlou, N H; Munck, O; Leyssac, P P.
In: Scandinavian Journal of Clinical & Laboratory Investigation, Vol. 48, No. 6, 1988, p. 509-12.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The influence of body posture on lithium clearance.
AU - Kamper, A L
AU - Strandgaard, S
AU - Holstein-Rathlou, N H
AU - Munck, O
AU - Leyssac, P P
N1 - Keywords: Adolescent; Adult; Female; Glomerular Filtration Rate; Humans; Kidney; Lithium; Lithium Carbonate; Male; Middle Aged; Posture; Potassium; Sodium; Supination
PY - 1988
Y1 - 1988
N2 - To establish appropriate standard circumstances for lithium clearance measurements, a study was undertaken in 12 healthy volunteers. In each subject, the glomerular filtration rate (GFR), as estimated by [51Cr]EDTA plasma clearance, and the renal clearances of lithium, sodium and potassium were measured four times at 1-week intervals: two in the supine and one in the sitting position, and one when the subject was walking around. Glomerular filtration rate was not influenced by posture changes. On the contrary, lithium clearance, which in the supine position was 30 +/- 9 ml/min (1 SD), tended to fall in the sitting position, and fell significantly to 26 +/- 5 ml/min (p less than 0.025) in walking subjects. Absolute proximal tubular reabsorption rate of fluid correspondingly rose from 83 +/- 16 to 92 +/- 15 ml/min (p less than 0.005) and sodium clearance fell from 1.52 +/- 0.81 to 1.00 +/- 0.52 ml/min (p less than 0.05) in walking subjects. Absolute distal reabsorption of sodium decreased during walking from 4052 +/- 1219 to 3449 +/- 658 mumol/min (p less than 0.025), while fractional distal reabsorption of sodium was unchanged. Our results show a rise in proximal tubular reabsorption during moderate physical activity. Hence, when renal tubular function is studied with the lithium clearance method, standardization of posture and physical activity is important. In such studies physical activity such as walking should particularly be avoided.
AB - To establish appropriate standard circumstances for lithium clearance measurements, a study was undertaken in 12 healthy volunteers. In each subject, the glomerular filtration rate (GFR), as estimated by [51Cr]EDTA plasma clearance, and the renal clearances of lithium, sodium and potassium were measured four times at 1-week intervals: two in the supine and one in the sitting position, and one when the subject was walking around. Glomerular filtration rate was not influenced by posture changes. On the contrary, lithium clearance, which in the supine position was 30 +/- 9 ml/min (1 SD), tended to fall in the sitting position, and fell significantly to 26 +/- 5 ml/min (p less than 0.025) in walking subjects. Absolute proximal tubular reabsorption rate of fluid correspondingly rose from 83 +/- 16 to 92 +/- 15 ml/min (p less than 0.005) and sodium clearance fell from 1.52 +/- 0.81 to 1.00 +/- 0.52 ml/min (p less than 0.05) in walking subjects. Absolute distal reabsorption of sodium decreased during walking from 4052 +/- 1219 to 3449 +/- 658 mumol/min (p less than 0.025), while fractional distal reabsorption of sodium was unchanged. Our results show a rise in proximal tubular reabsorption during moderate physical activity. Hence, when renal tubular function is studied with the lithium clearance method, standardization of posture and physical activity is important. In such studies physical activity such as walking should particularly be avoided.
M3 - Journal article
C2 - 3146132
VL - 48
SP - 509
EP - 512
JO - Scandinavian Journal of Clinical & Laboratory Investigation
JF - Scandinavian Journal of Clinical & Laboratory Investigation
SN - 0036-5513
IS - 6
ER -
ID: 8440116