Patients that work outdoors in a hot and/or humid environment may have significant insensible losses due to sweating, and thus it is important to explain to these patients that they will need to drink considerably more fluid than 2–3 L/day. Occupations that fit this scenario may include roofers, landscapers, construction workers, and lifeguards. An extreme example of this was reported in a study of 50 US Marines that were on a 1-month training exercise in the Mojave Desert during the month of July. Despite drinking an average of 17 L of water per day, the daily urine output decreased 68% to 0.52 L per day [10]. Teachers many times may self-restrict their fluid intake during school hours as they cannot leave their classrooms unattended for a bathroom break. Linder et al. sent electronic surveys focusing on urolithiasis in a hospital and showed that healthcare professionals who work in the operating room (including surgeons, anesthesiologists, nurses, operating room techs) reportedly have significantly less fluid intake compared to employees not working in the operating room (p = 0.04) and that working in the operating room was associated with a significantly increased risk of stone formation (HR 1.43; p = 0.04) [11]. Evaluating patients’ access to fluid as well as access to a bathroom and interruptions at work to use the bathroom is important, as patients may self-restrict fluid intake at work due to these factors [12]. Being able to tailor your dietary counseling with this population of patients, by recommending that they significantly increase their fluid intake as soon as they get home, is important. Sleep disturbances are another barrier to good fluid intake, and thus it is not unreasonable to have patients stop drinking fluid prior to bedtime as well as making sure that the patient is void prior to sleeping to minimize nocturia [12]. Truck drivers may have difficulty following certain dietary recommendations due to their long hours driving (they may self-restrict fluid intake to minimize bathroom stops) and because their diet intake may be restricted to processed foods (limited access to fresh fruits and vegetables) during their drives. Attention must also be placed on a patient’s bowel habits as diarrhea (loss of fluid in feces) in cases of gastric bypass or ileostomy can also be a factor in low urine volume. In order to help our patients decrease their stone recurrent risk, we must be willing to tailor our recommendations to each patient’s lifestyle and occupation (Table 17.2).

When discussing fluid consumptions , it is also important to determine what fluids the patient drinks on a regular basis [1]. A number of different beverages, such as alcoholic beverages, coffee, tea, and citrate-rich beverages, have been shown in observational studies to be associated with a lower risk of stone formation, while sugar-sweetened beverages have demonstrated an increased risk [13–18]. It is however important to understand that these beverages have not been evaluated in randomized controlled trials [1]. Though it is preferable for patients to consume citrate-rich beverages, recommending that patients try to avoid sugar-sweetened beverages and that they add additional citrate-rich fluid to what they already drink to increase their fluid consumption is important. The danger of having a patient replace what they were previously drinking with a citrate-rich beverage (as opposed to having them add citrate-rich beverages to their current fluid intake) is that they may drink less fluid overall when trying to substitute what they were previously drinking.

Other barriers to increasing fluid intake include “not liking the taste of water” and the lack of thirst awareness [12]. Solutions to these problems include considering a plethora of water flavors that are commercially available as well as considering timed drinking of fluid. Carrying a fluid container with visible fluid markings has been shown to help patients increase their fluid intake. Though we encourage our patients to have a high fluid intake, the real focus is on their urine output, and thus the AUA guidelines recommend stone formers to consume a fluid intake that will achieve a urine volume of at least 2.5 L daily [1]. In order to help patients determine if they are reaching that goal, we can determine their urine volume when they do their 24-h urine metabolic study, but it can also be convenient to give patients a urine hat to place on their toilet so that they can monitor their urine output when they are at home. Penniston et al. showed that specific gravity measured at specific time points during a 24-h interval can predict total urine volume (with a specific gravity <1.010 predicting a 24-h urine volume of greater than 2 L). Providing hydrometers or dipsticks to patients, along with instructions for accurate reading of results, may be used as biofeedback to help them gauge how well they are doing in order to reach their target daily urine volume. Furthermore, specific gravity measurements between regularly scheduled clinic visits may also provide information regarding variations in patients’ stone risk [19]. Urine color can be used as a rough gauge to help patients determine if they need to drink more fluid. Urine color charts are available and have been used in other clinical situations to help determine hydration status [20]. Setting a goal that the patient’s urine should be clear can help patients gauge how hydrated they are on a daily basis. It is however important to note that urine color by itself is not as accurate and should not be a replacement for a 24-h urine output measurement.