Effects of urinary volume on urinary concentrations of lead , 6 - aminolaevulinic acid , coproporphyrin , creatinine , and total solutes *

Urinary volume was related to urinary concentrations of lead, delta-aminolaevulinic acid (ALA), coproporphyrin (COPRO), creatinine, and total solutes in nine lead workers. On a log scale, linear relationships were found between urinary volume and the urinary concentrations. There was a certain difference in the extent of the effects of urinary volume on the urinary concentrations. For example, the concentration of creatinine was more affected by urinary volume than those of lead, ALA, and total solutes among the substances examined: similarly, the concentration of COPRO more than that of ALA. An equation was introduced to eliminate the effects of urinary volume on urinary concentrations. The effects of urinary volume on the concentrations adjusted to urinary specific gravity, osmolality, and creatinine are discussed in the light of these findings. Urinary lead, delta-aminolaevulinic acid (ALA), and coproporphyrin (COPRO), among the indicators of the dose and effects of lead, necessitate measuring the urinary concentrations. It has been known for many years that these concentrations vary over a wide range and are inversely correlated with urinary volume throughout each 24-hour period. No factor other than urinary volume seems to play any important part in the induction of the variation.1 It remains unclear, however, to what extent those concentrations are affected by urinary volume. The excretion of lead, ALA, and total solutes was found to decrease when urinary volume was reduced: conversely, that of COPRO and creatinine was independent of urinary volume.2 This observation suggested that the effect of urinary volume is greater on the concentrations of COPRO and creatinine than on those of lead, ALA, and total solutes. A further assumption is that the extent of the effect of urinary volume can be quantitatively different among those substances. In this paper the relationships between urinary volume and urinary concentrations of lead, ALA, *This paper is based on part of a dissertation submitted for the degree of MSc in occupational medicine at the London School of Hygiene and Tropical Medicine, University of London. Received 27 June 1978 Accepted 4 April 1979 COPRO, creatinine, and total solutes are quantitatively analysed to verify the assumption. In addition, an equation is introduced to eliminate the effects of urinary volume on urinary concentrations. Subjects and methods SUBJECTS Nine male lead workers (plastics worker, lead smelter, welder, pigment maker, type founder, paint maker, galvaniser, and two stereotype founders) were admitted to hospital for diagnosis, prophylaxis, or treatment of lead poisoning. At the time of examination, six subjects had not been exposed to lead for more than three weeks; the two subjects (1 and 4) for five days; and one subject (No 9) for three days. Blood lead concentrations ranged from 0 3 ,umol/l (7 ,ugldl) to 2-9 ,umol/l (61 ,tg/dl) (mean 1-7 ,umol/l (35 tzg/dl)) at the time of examination. Mean age was 49 years (range 21-63). No subject showed albuminuria, and renal function tests (PSP test and Fishberg concentration test) and serum creatinine concentrations were normal or borderline in all. COLLECTION OF URINARY SAMPLES After maintaining their usual intake of food and water for two days, the subjects drank about 0 25 1 water each day for another two days, and were then loaded with about 3 1 water daily for two successive 50 group.bmj.com on June 20, 2017 Published by http://oem.bmj.com/ Downloaded from