A comparison of the effects of potassium citrate and sodium bicarbonate inthe alkalinization of urine in homozygous cystinuria

For many years, urine alkalinization has been one of the cornerstones in th e treatment of homozygous cystinuria. Because of the relationship found bet ween the excretion of urinary sodium and cystine, potassium citrate has eme rged as the preferred sodium-free alkalizing agent. To evaluate the usefuln ess of potassium citrate for urine alkalization in cystinuric patients, sod ium bicarbonate and potassium citrate were compared in 14 patients (10 on t iopronin treatment and four without treatment with sulfhydryl compounds). T he study started with I week without the use of any alkalizing agents (Peri od 0) followed by 2 weeks with sodium bicarbonate (Period 1) and 2 weeks wi th potassium citrate (Period 2). Urinary pH, volume, excretion of sodium, p otassium, citrate and free cystine, as well as the plasma potassium concent ration, were recorded. Potassium citrate was shown to be effective as an al kalizing agent and, in this respect, not significantly different from sodiu m bicarbonate. Even though a normal diet was used, a significant increase i n urinary sodium excretion was observed with sodium bicarbonate (Period 1). Urinary potassium and citrate excretion increased with potassium citrate ( Period 2). A significant correlation was found between urinary sodium and c ystine in the tiopronin-treated patients. No significant differences in cys tine excretion were recorded in Periods 0, 1 and 2. Plasma potassium was si gnificantly higher during Period 2, but only one patient developed a mild h yperkalemia (5.0 mmol/l). The use of potassium citrate for urine alkalizati on in homozygous cystinuria is effective and can be recommended in the abse nce of severe renal impairment.