Figure 1. (A) Illustration of the progression of blood pH and HCO3− levels as determined by venous blood gas analysis. Despite persistent metabolic acidosis under conservative treatment, acidosis significantly improved following hemodialysis, with no recurrence observed. (B) U-Hippuric indicates urinary hippuric acid. S-Cr indicates serum creatinine levels. Urinary hippuric acid levels increased after hemodialysis, reflecting improved renal clearance due to the correction of metabolic acidosis. Serum creatinine levels peaked and then declined, indicating enhanced excretion. (C) U-β2MG indicates urinary β2-microglobulin and U-NAG shows urinary N-acetyl-β-D-glucosaminidase. Urinary tubular markers, β2-microglobulin (U-β2MG) and N-acetyl-β-D-glucosaminidase (U-NAG), increased on the third day, likely indicating tubular damage from hippuric acid exposure, with a delayed response. (D) U-AG stands for Urinary Anion Gap and U-Osmolarity GAP refers to the urinary osmolality gap. Improvements in renal tubular acidosis were observed with both the avoidance of toluene exposure and treatment, as reflected in the reductions of both the urinary AG and osmolality gap. Despite the substantial excretion of urinary hippuric acid, the urinary osmolality gap did not show a significant increase. This can be attributed to a time lag of approximately half a day between measurements, during which urinary hippuric acid had already decreased substantially, and only the improvement in renal tubular acidosis was being observed.