The effects of water restriction and water loading on urinary excretion of lead, delta-aminolevulinic acid and coproporphyrin.

Alterations in daily urinary excretion of lead, delta-aminolevulinic acid (ALA), coproporphyrin, creatinine and total solutes following water restriction and water loading were examined in nine lead workers. Excretion of lead, ALA and total solutes was significantly decreased when urinary volume was reduced, showing that these values are dependent on urinary volume: conversely, excretion of coproporphyrin and creatinine was independent of urinary volume. Excretion of lead and total solutes was also dependent on creatinine excretion. The renal excretory mechanism of lead, ALA and coproporphyrin is discussed in the light of these findings.