Kristina L. Penniston

Quantitative Assessment of Citric Acid in Lemon Juice, Lime Juice, and Commercially-Available Fruit Juice Products

BACKGROUND AND PURPOSE Knowledge of the citric acid content of beverages may be useful in nutrition therapy for calcium urolithiasis, especially among patients with hypocitraturia. Citrate is a naturally-occurring inhibitor of urinary crystallization; achieving therapeutic urinary citrate concentration is one clinical target in the medical management of calcium urolithiasis. When provided as fluids, beverages containing citric acid add to the total volume of urine, reducing its saturation of calcium and other crystals, and may enhance urinary citrate excretion. Information on the citric acid content of fruit juices and commercially-available formulations is not widely known. We evaluated the citric acid concentration of various fruit juices. MATERIALS AND METHODS The citric acid content of 21 commercially-available juices and juice concentrates and the juice of three types of fruits was analyzed using ion chromatography. RESULTS Lemon juice and lime juice are rich sources of citric acid, containing 1.44 and 1.38 g/oz, respectively. Lemon and lime juice concentrates contain 1.10 and 1.06 g/oz, respectively. The citric acid content of commercially available lemonade and other juice products varies widely, ranging from 0.03 to 0.22 g/oz. CONCLUSIONS Lemon and lime juice, both from the fresh fruit and from juice concentrates, provide more citric acid per liter than ready-to-consume grapefruit juice, ready-to-consume orange juice, and orange juice squeezed from the fruit. Ready-to-consume lemonade formulations and those requiring mixing with water contain < or =6 times the citric acid, on an ounce-for-ounce basis, of lemon and lime juice.

Serum Carotenoid Concentrations in Postmenopausal Women from the United States with and without Osteoporosis

Antioxidant defenses may be compromised in osteoporotic women. Little is known about fruit and vegetable or carotenoid consumption among postmenopausal women. The primary carotenoids in human serum are alpha- and beta-carotene, lycopene, beta-cryptoxanthin, lutein, and zeaxanthin. This study investigated the interrelationships among serum carotenoid concentrations, fruit and vegetable intake, and osteoporosis in postmenopausal women (n = 59, 62.7 +/- 8.8 y). Bone density was assessed by dual energy x-ray absorptiometry and osteoporosis diagnosis was based upon T-scores. Serum samples (n = 53) and three-day diet records (n = 49) were analyzed. Logistic regression analyzed differences between carotenoids after adjusting for serum retinol; supplement usage; milk, yogurt, fruit, and vegetable intake; and body mass index (BMI). Pearson statistics correlated carotenoids with specific fruit or vegetable intake. Serum lycopene concentrations were lower in the osteoporosis group than controls (p = 0.03). Beta-cryptoxanthin intake was higher in the osteoporosis group (p = 0.0046). Total fruit and vegetable intakes were correlated with serum lycopene and beta-cryptoxanthin (p = 0.03, 0.006, respectively). Serum alpha-carotene concentration was associated with carrot intake, and zeaxanthin and beta-cryptoxanthin with lettuce intake. Carotenoids that may have beneficial skeletal effects are lower in women with osteoporosis. Research is needed to identify potential protective mechanisms or utilization of carotenoids during osteoporosis.

Gastric Band Placement for Obesity is Not Associated With Increased Urinary Risk of Urolithiasis Compared to Bypass

PURPOSE Obesity is associated with multiple health risks. Bariatric surgery is a treatment for clinically severe obesity and is known to increase urolithiasis risk. However, trends in risk over time are not well characterized. Moreover little attention has been devoted to laparoscopic gastric band placement. A comparison of urinary risk of urolithiasis after the Roux-en-Y and gastric banding procedures was performed. MATERIALS AND METHODS We evaluated 24-hour urine collections from 39 subjects (11 male and 28 female, mean age 51 years) after bariatric surgery. Of these subjects 27 underwent Roux-en-Y gastric bypass and 12 had gastric banding procedures. Mean time since surgery was 3.4 and 2.1 years for the Roux-en-Y gastric bypass and gastric banding groups, respectively. RESULTS Urine volume was low in both groups (less than 1.5 l daily). Urinary calcium excretion was lower (p = 0.001) in the Roux-en-Y gastric bypass (100 mg daily) vs the gastric banding group (191 mg daily). After Roux-en-Y gastric bypass surgery 48% had a urinary oxalate of 45 mg daily or more compared to 25% after gastric banding. Urinary citrate was less than 370 mg daily for 14 subjects in the Roux-en-Y gastric bypass and 1 in the gastric banding group. All patients were taking calcium supplements. Dietary intake of high oxalate foods did not correlate with urinary oxalate excretion or with hyperoxaluria. CONCLUSIONS Our study confirms the risk of urinary stones following the Roux-en-Y gastric bypass procedure as a result of hyperoxaluria, low urine volume and hypocitraturia. Those with gastric banding placement had low urine volumes. Future studies should elucidate the effect of nutrition and/or pharmacological therapy on stone risk of both surgeries as their incidence increases.

Development of an Instrument to Assess the Health Related Quality of Life of Kidney Stone Formers

PURPOSE Urolithiasis is associated with pain and other decreases in health related quality of life, yet there is no urolithiasis specific instrument to measure quality of life. Quality of life is an important end point in the management of urolithiasis. Therefore, we developed the Wisconsin StoneQOL, a disease specific instrument to assess the quality of life of patients with urolithiasis. MATERIALS AND METHODS Patients and urology providers identified important concepts related to quality of life of stone formers in groups and in individual cognitive interviews. Patients were recurrent stone formers including those with and those without current stones. A preliminary instrument was created, followed by patient feedback and item reduction. A 28-question instrument was ultimately developed which was tested for reliability as well as internal face, construct and discriminant validity in 248 stone formers. RESULTS The internal consistency (for questions within domains) was high (mean Cronbachs α = 0.81). Correlation between domains was confirmed (Cronbachs α = 0.86). Discriminant validity was shown as stone formers with current stones scored lower than those who were stone-free. Among patients with active stones, those with symptoms scored lower on most questions and for the total score (p <0.0001) than those who were asymptomatic. CONCLUSIONS The Wisconsin StoneQOL holds promise as a disease specific instrument that captures the unique symptoms and challenges associated with urolithiasis. As such, the Wisconsin StoneQOL is capable of assessing the health related quality of life of stone formers at various points along the disease continuum. Future assessment will establish minimal clinically important differences for use in individual patients.

Effect of dietary changes on urinary oxalate excretion and calcium oxalate supersaturation in patients with hyperoxaluric stone formation.

OBJECTIVES To test the hypothesis that patients with hyperoxaluria, who modified their dietary calcium intake, would reduce their urinary oxalate excretion without raising their urinary calcium excretion. Diet is a major factor in idiopathic calcium oxalate urolithiasis, yet controversy exists regarding the ideal clinical recommendations. Approximately 20% of patients with calcium oxalate stone formation have hyperoxaluria (> or = 45 mg oxalate/d). Calcium supplements to bind dietary oxalate have been suggested, but clinical evidence of this therapy is lacking. METHODS Of 144 adult patients with stone formation seen by a registered dietitian from September 2006 to September 2007, 26 (18%) had hyperoxaluria on > or = 1 24-hour urinalyses. Of those with > or = 2 complete 24-hour collections and whose hyperoxaluria was observed before their last visit with the registered dietitian, 22 patients were identified. The patients were retrospectively separated into 2 groups according to whether they had been advised dietary changes alone (diet group, n = 10) or calcium citrate with meals, in addition to the dietary changes (supplement group, n = 12). The mean follow-up time was 317 and 266 days for the diet and supplement groups, respectively. Statistical comparisons within and between groups were made for urinary risk factors. RESULTS Urinary oxalate excretion decreased from 56 to 43 mg/d and from 60 to 46 mg/d in the diet and supplement groups, respectively (P = .003 and P = .038, respectively). Calcium oxalate supersaturation decreased from 3.48 to 1.83 and from 2.37 to 1.52 in the diet and supplement groups, respectively (P = .043 and P = .002, respectively). Urinary calcium excretion did not change in either group. CONCLUSIONS Gastrointestinal binding of oxalate by calcium is an effective clinical strategy for hyperoxaluria, whether mediated by calcium citrate with meals or by inclusion of calcium-containing foods with meals.

Vitamin D repletion does not alter urinary calcium excretion in healthy postmenopausal women

To evaluate, in a posthoc analysis of a previous study, whether vitamin D repletion in postmenopausal women with insufficient vitamin D increases urinary calcium excretion, as vitamin D therapy might contribute to hypercalciuria and calcium stones in susceptible individuals, and the effect of vitamin D on the risk of urolithiasis warrants attention.

Vitamin A in dietary supplements and fortified foods: Too much of a good thing?

Vitamin A consumption by many Americans is quite high, in part because of the consumption of fortified foods and the use of vitamin supplements. Most multivitamin supplements provide two or more times the recommended dietary allowance (RDA) for vitamin A because the daily value (DV) is based on 1968 and not current RDAs. Consumption of just one multivitamin often provides excessive vitamin A, the majority of it as preformed vitamin A esters. Given recent epidemiologic evidence that suggests a link between chronic intakes of vitamin A that exceed the RDA and hip fractures, it may be time to reexamine food and supplement fortification policies and to discontinue the clinical practice of prescribing two multivitamins to the elderly and other patients whose needs for certain micronutrients are high.

Patients With and Without Prior Urolithiasis Have Hypocitraturia and Incident Kidney Stones While on Topiramate

OBJECTIVES To determine the effect of topiramate (TPM) on 24-hour urinary parameters in stone formers. TPM is frequently prescribed for epilepsy, migraine headaches, and eating disorders. METHODS Twelve stone-forming patients who were prescribed TPM between 2003 and 2008 were identified from our stone clinic. Of these, 9 patients (M:F, 4:5; 47 ± 7.1 y SEM) underwent a full metabolic workup (UroRisk Diagnostic Profile, Mission Pharmacal Reference Laboratory, San Antonio, TX) and were included for review. Parameters examined include duration and dose of the drug, 24-hour urine calcium, oxalate, citrate, volume, and pH. If available, urine parameters before taking TPM and after either stopping it or receiving potassium citrate therapy were recorded. RESULTS Mean duration taking TPM was 17 ± 5.2 months (range, 3-43) months and median dose was 100 mg (range, 25-300) daily. Mean urinary citrate excretion was 136 ± 29 mg/d (range, 30-280) in all patients taking the drug. Three patients were either taken off the drug or placed on potassium citrate, resulting in a mean increase in urinary citrate of 374 mg/d (65%). TPM dosage correlated inversely with urinary citrate excretion (Pearson correlation coefficient = -0.73). CONCLUSIONS TPM therapy is associated with a profound, dose-dependent decrease in urinary citrate, leading to increased lithogenic risk. This hypocitraturia persists even after long periods of taking the drug. Urologists should be aware of the stone-forming risk of this medication. Strategies to maintain therapeutic urinary citrate concentrations in patients on TPM are needed.

Acetazolamide Is an Effective Adjunct for Urinary Alkalization in Patients With Uric Acid and Cystine Stone Formation Recalcitrant to Potassium Citrate

OBJECTIVES Acetazolamide has been proposed as a treatment adjunct for patients with cystine and uric acid stone formation recalcitrant to standard alkalization therapy. We evaluated the effect of acetazolamide in urinary alkalization in patients with uric acid and cystine stone formation recalcitrant to potassium citrate alone. METHODS An institutional review board-approved, retrospective chart review identified 12 patients at 2 sites who had been prescribed acetazolamide as a treatment adjunct to potassium citrate for uric acid or cystine stones from 1997 to 2007. We evaluated the urine studies, metabolic evaluations, surgical interventions, and stone recurrence or growth. RESULTS The mean follow-up was 46.1 months (range 11-86). Ten patients (83%) were categorized as compliant. Of the 2 patients excluded from the study, 1 was noncompliant with the medication, and the other was lost to follow-up. Of the 10 patients who were compliant with the treatment, 5 (50%) developed adverse effects from the medication requiring discontinuation. Of the remaining 5 patients (50%) who tolerated the medication and remained compliant, 3 (60%) were stone free at a mean follow-up of 42 months. Two patients continued to form stones, including one who developed calcification of an existing uric acid stone. Both patients required surgical intervention. The mean urinary pH before treatment was 5.9 (range 5-7) and after treatment was 7.2 (range 6.5-8.5; P = .001). CONCLUSIONS Acetazolamide was effective in increasing the urinary pH in patients with uric acid and cystine stone formation who were already taking potassium citrate. Caution must be taken when prescribing acetazolamide, because it could be poorly tolerated and can induce calcium phosphate stone formation.

Diet and alternative therapies in the management of stone disease.

Although nonnutritional factors affect the risk for renal stone development, nutrition is widely viewed as contributory and is frequently included as part of the therapeutic regimen in secondary stone prevention. In this article, the therapeutic application of nutritional recommendations to address specific risk factors of urolithiasis is reviewed. The article focuses on calcium-containing and uric acid stones. The general approach to nutrition therapy is addressed first, and empiric and tailored approaches are discussed. How to assess a patients nutrition risk for lithogenesis is reviewed, and the implementation or practice of nutrition therapy is discussed.