Change of 24-hour Urinary Citrate Level after Dietary Manipulation with Lemon Juice in Urolithiasis Patients / 대한비뇨기과학회지

PURPOSE: Citrate is a well recognized inhibitor of the formation of calcium oxalate and calcium phosphate stones. Hypocitraturia is a common etiology of recurrent calcium nephrolithiasis, with an incidence of 19 to 63%. Potassium citrate therapy can be a useful therapeutic approach for the management of calcium nephrolithiasis. But pharmacological treatment of hypocitraturic calcium nephrolithiasis requires taking too many tablets, or numerous crystal package or liquid supplements throughout the day. This cumbersome regimen often decreases patient compliance. We administered dietary citrate via lemon juice to stone former and evaluated the change of citrate levels. MATERIALS AND METHODS: The prospective study included 7 women and 8 men with documented recurrent or multiple urinary stone disease. None of the subjects suffered from renal impairment, urinary tract infection and other metabolic disorder. Controls comprised 6 voluntary men. They had no previous stone history and no evidence of stone. Patients ingested total 1 liter of lemon juice(containing 4.0gm/L.citrate) divided at 6 hours interval without strict diet restriction. Urine specimens were obtained for urinary citrate levels after 2-3days of lemon juice therapy and compared to pre-lemon juice baseline values. RESULTS: All 15 patient showed increased urinary citrate levels during lemon juice therapy. Average urinary citrate levels increased from 146+/-109mg/day at baseline to 453+/-226mg/day during treatment(p0.05). Urinary pH increased from 5.9+/-0.4 at baseline to 6.8+/-0.6 during treatment(p<0.05). No patient complained of gastrointestinal discomforts. CONCLUSIONS: Citrate supplementation with lemon juice increased urinary citrate levels and urinary pH. Lemon juice is well tolerated dietary source of citrate and would be beneficial in the control of calcium urolithiasis.

Urinary citrate excretion in normal adults.

For 60 healthy subjects, aged 18-48, the urinary citrate excretion was studied by enzymatic method of Toftegaard Nielsen. The mean values in 24hr. urine were 1.44+0.61 mmole/day, 1.33+0.54 mmole/l. and 1.80+1.06 mmole/gm Cr, respectively. In single voided urine specimens, urinary citrate concentrations were 1.44+0.74 mmole/l and 1.82+0.98 mmole/gm Cr. Females had a higher mean value than males. There was no significant difference in the concentration of citrated excreted in different periods of the day when the excretion was expreesed as mmole per gram of creatinine, but when expressed in mmole per litre, the 10 pm-6 am period was different from others. The concentration of excreted citrate in each period correlated well with the 24 hour excretion, especially when it was expressed as mmole per litre (corr. Coeff. 0.55-0.9). Therefore, a single voided specimen can be used in the evaluation of total daily citrate excretion.