Variation in Urine Electrolytes, pH and Specific Gravity Throughout the Day and the Effect of Increased Fluid Intake on Intra-Day Urine Composition

20 subjects will be recruited and consented in the Urology Clinic office. Subjects will complete a questionnaire asking about weight, height, history of kidney stones, whether they are on any diuretics, medications that alter urine chemistries, or special diets. BMI will be calculated. Day 1 will begin at 5p.m. on the day before first morning void is collected. The subjects will collect a spot urine sample on the first void at home, then at 9-10AM, 1-2 PM and 4-5PM. They will be provided 4 sterile urine cups labeled for the different timed collection marked at the 20-30 ml line to indicate how much urine should be collected. Subjects will be instructed to refrigerate their first voids.The 2nd, 3rd and 4th void samples will be collected in the office during the designated times, and given to study personnel. The subjects will record the time of each void, the time given to the study representative, the times they eat, and their approximate fluid intake on the provided diaries. Subjects will be asked not to void outside of the timed collections. If they do void outside of these times, they will be asked to record the extra times that they void.

On Day 2, 3, and 4 the subject will drink a bottle of water with True Lemon after 5pm. On days 3 and 4 the subjects will double their fluid intake using Day 1 as a guide. On Day 4 the subjects will collect 4 urine samples as previously described for Day1. They will be instructed to mix 1 packet of True lemon in one 16.9oz (500 mL) bottle of Poland Spring. All True Lemon packets (True Citrus, 11501 Pocomoke Court Suite D, Baltimore, MD 21220). and Poland Spring (Nestle Waters North America) bottles will be provided to subjects by the research study team.

UA dipsticks will be used in office to evaluate for pH and specific gravity. Samples will also be sent to lab for evaluation of chemical composition of creatinine, citrate, and calcium. Electrolytes will be indexed against creatinine to evaluate their concentrations without having a 24-hour void volume amount A sample of citrate-Poland Spring will be sent to Litholink for analysis of Calcium and Citrate for reference.