[Clinical study on cystinuria in children--the stone management and the prevention of calculi recurrence]

Minimal change disease induced by tiopronin: a rare case report and a review of the literature

Tiopronin (TP), a glycine derivative with a free thiol, is extensively used for the treatment of cystinuria. Moreover, TP is usually prescribed as hepatoprotective medicine in China. In the present case, a 36-year-old female who presented with foamy urine and general edema was admitted to the hospital. She had been taking TP for six months to treat drug-induced liver injury due to anti-tuberculosis drugs including isoniazid, rifampicin and pyrazinamide. The urine tests at admission revealed nephritic-range proteinuria with a daily urinary protein level of 8,024 mg. Meanwhile, albumin and cholesterol levels were abnormal. The light microscopy was negative and electron microscopy showed foot process effacement. Thus, minimal change disease (MCD) was diagnosed, and TP was consequently discontinued. Finally, the patient accomplished complete remission within five weeks after the cessation of TP without undergoing glucocorticoid therapy. TP was speculated to play an antigenic role in this adverse effect. To date, there are only two similar cases documented in the literature. Herein, we first report a case of a Chinese patient who generated MCD after prolonged TP administration. Clinicians should be wary of the occurrence of MCD due to TP when administering long-term therapy of TP. A weekly urinalysis may be useful for early identification of TP-induced MCD.

Penicillamine therapy for pediatric cystinuria: experience from a cohort of American children

PURPOSE

Cystinuria, an inherited defect of dibasic amino acid transport, causes accumulation of urinary cystine and cystine urolithiasis. In adults penicillamine reduces stone formation but has a high incidence of dose limiting toxicity. We evaluated the effects of penicillamine in preventing stone formation and with respect to toxicity in our cystinuria cohort at a pediatric biochemical genetics clinic.

MATERIALS AND METHODS

We reviewed the charts of all 11 children with cystinuria treated at our clinic using a gradual dose escalation of penicillamine. Mean +/- SD patient age at diagnosis was 5.8 +/- 4.3 years (range 1.2 to 12). We tracked urinary cystine concentration before and after initiation of treatment, penicillamine side effects and incidence of new stones during maintenance therapy.

RESULTS

During the gradual escalation of penicillamine to the target dose none of the 11 patients experienced toxicity and all had improved urinary cystine concentration (mean +/- SD percent reduction 54% +/- 25%, range 5% to 81%). We followed the patients for a total of 1,203 months (mean +/- SD 109 +/- 73 months, range 41 to 221), periodically assessing urinary cystine concentration, urine protein content, complete blood count, blood urea nitrogen, creatinine and liver function. During this time only 2 patients experienced significant side effects and no patient had stones or stone crises while compliant with treatment.

CONCLUSIONS

In our cohort penicillamine was well tolerated after gradual initiation and it reduced urinary cystine concentration. Long-term compliance with the medication appeared to protect patients from acute stone crises.

Extracorporeal shock wave lithotripsy for cystine urolithiasis in children: outcome and complications

The Siemens Lithostar Litotriptor was used to treat 6 children with cystine nephrolithiasis, previously treated by open surgery. Five children had renal calculi (3 multiple caliceal, 2 pelvis) and one had ureteral calculus. Stone size ranged from 0.2-2.5 cm in diameter, and stone burden was from 0.24 to 10.81 cm3 per kidney. From one to 4 ESWL sessions per unit were applied, with a total of 1,800 to 12,000 shock waves. The stone free rate at 3 months was 50%. A complete elimination was obtained with cystine stones in renal pelvis and ureter, however, up to 4 ESWL treatments failed in caliceal stones. Rather location of cystine calculi than previous surgery was associated with ESWL success rate. Two patients with positive urine cultures were successfully treated with appropriate antibiotics before ESWL was attempted. Perirenal hematoma was major complication demonstrated by radionuclide scintigraphy in one patient, and resolved spontaneously by 3 months. In the combined treatment of cystine urolithiasis in children ESWL, as auxillary procedure, was safe and effective in pelvis stone but failed in caliceal stones. Medical dissolution for retained fragments was found effective.