Secondary oxalosis induced by xylitol concurrent with lithium-induced nephrogenic diabetes insipidus: a case report

Background

Xylitol is an approved food additive that is widely used as a sweetener in many manufactured products. It is also used in pharmaceuticals. Secondary oxalosis resulting from high dietary oxalate has been reported. However, reported cases of oxalosis following xylitol infusion are rare.

Case presentation

A 39-year-old man with a 16-year history of organic psychiatric disorder was hospitalized for a laparoscopic cholecystectomy because of cholecystolithiasis. He had been treated with several antipsychotics and mood stabilizers, including lithium. The patient had polyuria (> 4000 mL/day) and his serum sodium levels ranged from 150 to 160 mmol/L. Urine osmolality was 141 mOsm/L, while serum arginine vasopressin level was 6.4 pg/mL. The patient was diagnosed with nephrogenic diabetes insipidus (NDI), and lithium was gradually discontinued. Postoperative urine volumes increased further to a maximum of 10,000 mL/day, and up to 10,000 mL/day of 5% xylitol was administered. The patient’s consciousness level declined and serum creatinine increased to 4.74 mg/dL. This was followed by coma and metabolic acidosis. After continuous venous hemodiafiltration, serum sodium improved to the upper 140 mmol/L range and serum creatinine decreased to 1.25 mg/dL at discharge. However, polyuria and polydipsia of approximately 4000 mL/day persisted. Renal biopsy showed oxalate crystals and decreased expression of aquaporin-2 (AQP2) in the renal tubules. Urinary AQP2 was undetected. The patient was discharged on day 82 after admission.

Conclusions

Our patient was diagnosed with lithium-induced NDI and secondary oxalosis induced by excess xylitol infusion. NDI became apparent perioperatively because of fasting, and an overdose of xylitol infusion led to cerebrorenal oxalosis. Our patient received a maximum xylitol dose of 500 g/day and a total dose of 2925 g. Patients receiving lithium therapy must be closely monitored during the perioperative period, and rehydration therapy using xylitol infusion should be avoided in such cases.

Human SLC26A1 gene variants: a pilot study

Kidney stones are a global health problem, incurring massive health costs annually. Why stones recur in many patients remains unknown but likely involves environmental, physiological, and genetic factors. The solute linked carrier (SLC) 26A1 gene has previously been linked to kidney stones in mice. SLC26A1 encodes the sulfate anion transporter 1 (SAT1) protein, and its loss in mice leads to hyperoxaluria and calcium oxalate renal stones. To investigate the possible involvement of SAT1 in human urolithiasis, we screened the SLC26A1 gene in a cohort of 13 individuals with recurrent calcium oxalate urolithiasis, which is the commonest type. DNA sequence analyses showed missense mutations in seven patients: one individual was heterozygous R372H; 4 individuals were heterozygous Q556R; one patient was homozygous Q556R; and one patient with severe nephrocalcinosis (requiring nephrectomy) was homozygous Q556R and heterozygous M132T. The M132 amino acid in human SAT1 is conserved with 15 other species and is located within the third transmembrane domain of the predicted SAT1 protein structure, suggesting that this amino acid may be important for SAT1 function. These initial findings demonstrate genetic variants in SLC26A1 of recurrent stone formers and warrant wider independent studies of SLC26A1 in humans with recurrent calcium oxalate stones.

Urinary biochemistry in occupational exposure to glycol ethers

Glycol ethers and glycol ether acetates are dehydrogenated to alkoxyacetic acid congeners which may serve as biological indicators of exposure. The ethereal bond may also be cut in an oxidation reaction catalyzed by the mixed function oxidase. In case of ethylene glycol, the eventual endproduct is oxalic acid. Urinary oxalic acid and alkoxyacetic acid excretion together was found to relate to the decrease of the succinate dehydrogenase activity (SDH) as an indicator of renal mitochondrial effects. The excretion of ammonia by exposed workers was doubled as compared to controls. The excretion of chloride was found to be smaller in the exposed than in controls. The excretion of calcium and glycosaminoglycans (GAG) among exposed workers were similar compared to controls.