Research prioritization of men's health and urologic diseases.

OBJECTIVES: We sought to determine whether disease representation in the Cochrane Database of Systematic Reviews (CDSR) reflects disease burden, measured by the Global Burden of Disease (GBD) Study as disability-adjusted life-years (DALYs). MATERIALS AND METHODS: Two investigators performed independent assessment of ten men's health and urologic diseases (MHUDs) in CDSR for systematic review and protocol representation, which were compared with percentage of total 2010 DALYs for the ten conditions. Data were analyzed for correlation using Spearman rank analysis. RESULTS: Nine of ten MHUDs were represented by at least one CDSR review. There was a poor and statistically insignificant positive correlation between CDSR representation and disease burden (rho = 0.42, p = 0.23). CDSR representation was aligned with disease burden for three conditions, greater than disease burden for one condition, and less than disease burden for six conditions. CONCLUSIONS: These results yield high-quality estimates to inform future research prioritization for MHUDs. While prioritization processes are complex and multi-faceted, disease burden should be strongly considered. Awareness of research priority setting has the potential to minimize research disparities on a global scale.

Gel Rolls Increase Percutaneous Nephrolithotomy Radiation Exposure.

Introduction: Despite increasing interest in reducing radiation doses during endoscopic stone surgery, there is conflicting evidence as to whether percutaneous nephrolithotomy (PCNL) positioning (prone or supine) impacts radiation. We observed clinically that a patient placed prone on gel rolls had higher than expected radiation with intraoperative CT imaging and that gel rolls were visible on the coaxial imaging. We hypothesized that gel rolls directly increase radiation doses. Methods: Anthropomorphic experiments to simulate PCNL positions were performed using a robotic multiplanar fluoroscopy system (Artis Zeego Care+Clear, Siemens) and a 5-second coaxial imaging protocol (5s BODY). A fluoroscopy phantom was placed in various positions, including prone on a gel roll; prone on blankets of equal thickness; prone and supine directly on the table; and modified supine (MS) positions using a thin gel roll or rolled blanket. Impacts of C-arm direction and use of a 1 L saline bag were also evaluated. Measured dose area product (DAP) was compared for the groups. Results: Measured DAP was found to increase by 146 µGy*m2 (287%) when prone on gel rolls compared with only 62.29 (23%) when placed on blankets of equal thickness, although the model likely both overstates the relative impact and understates the absolute impact that would be seen clinically. Measured DAP between experimental groups also varied considerably despite fluoroscopy time being held constant. Conclusions: Our experiments support our hypothesis that gel rolls directly increase radiation dose, which has not been previously reported, using an anthropomorphic model. Surgeons should consider radiolucent materials for positioning to limit radiation exposure to patients and the surgical team.

Novel Prostate Biopsy Technique Using Imaging Fusion in a Patient With Absent Rectum.

INTRODUCTION: A 70-year-old male with prior total colectomy for ulcerative colitis was referred for elevated prostate specific antigen (PSA) (8.01) with PIRADS 4 lesion on magnetic resonance imaging (MRI). Described is a novel technique using pre-operative multi-parametric prostate MRI and intraoperative computed tomography (CT) 3D/3D fusion for systematic and targeted prostate biopsy in a patient lacking a rectum. TECHNICAL CONSIDERATIONS: Under general anesthesia, an ultra-low-dose (ULD) cone beam CT was performed in supine position using a robotic-armed fluoroscopy system (Artis Zeego Care+Clear, Siemens). 3D/3D auto-registration of the femoral heads and prostate from the MRI and ULD CT was performed. The prostate edges and two areas of concern were marked. Then, reduced-dose fluoroscopy-guided prostate biopsy was performed transperineally using triangulation technique. 27 prostate biopsy cores were obtained. Grade group 5 (Gleason 4+5=9) prostate cancer was identified in two cores from the targeted lesion and one core from the prostate base. The remaining twenty-four biopsies were negative for malignancy. Surgical time was 81 minutes. PSMA scan demonstrated no metastasis or lymphadenopathy. Robotic-assisted laparoscopic radical prostatectomy was performed without complications. Final pathology demonstrated T3a, grade group 5 prostate adenocarcinoma involving 10% of the prostate volume with negative surgical margins. CONCLUSION: This is the initial report of fluoroscopy-guided prostate biopsy using imaging fusion techniques in a patient without a rectum. This technique allowed precise identification of localized, very high-risk prostate cancer with over three times the number of cores, and much lower radiation dose, than typical CT-guided biopsies. Our technique could provide a new paradigm in targeted prostate biopsy.

Optimizing antibiotic management for patients with acute appendicitis: A quality improvement study.

BACKGROUND: To decrease surgical site infections after appendectomy for acute appendicitis, preoperative broad-spectrum antibiotics are often used in clinical practice. However, this treatment strategy has come under scrutiny because of increasing rates of antibiotic-resistant infections. METHODS: The aim of this multisite quality improvement project was to decrease the treatment of uncomplicated acute appendicitis with piperacillin-tazobactam without increasing the rate of surgical site infections. Our quality improvement intervention had 2 distinct components: (1) updating electronic health record orders to encourage preoperative administration of narrow-spectrum antibiotics and (2) educating surgeons and emergency department clinicians about selecting appropriate antibiotic therapy for acute appendicitis. Patient demographics, clinical characteristics, and outcomes were compared 6 months before and after implementation of the quality improvement intervention. RESULTS: A total of 352 laparoscopic appendectomies were performed during the 6-month preintervention period, and 369 were performed during the 6-month postintervention period. The preintervention period and postintervention period groups had similar baseline demographics, vital signs, and laboratory test values. The rate of preoperative piperacillin-tazobactam administration significantly decreased after the intervention (51.4% preintervention period vs 20.1% postintervention period, P < .001). The rate of surgical site infections was similar in both groups (superficial surgical site infections = 1.4% preintervention period vs 0.8% postintervention period, P = .50; deep surgical site infections = 1.1% preintervention period vs 0.0% postintervention period, P = .06; and organ space surgical site infections = 3.1% preintervention period vs 3.0% postintervention period, P > .99). Rates of 30-day readmission, reoperation, and Clostridioides difficile infection also did not differ between groups. CONCLUSION: Our quality improvement intervention successfully decreased piperacillin-tazobactam administration without increasing the rate of surgical site infections in patients with acute appendicitis.

Ultralow-Dose Intraoperative Computed Tomography During Endoscopic Stone Surgery: A Quality Improvement Project.

Objectives: To improve care in patients with large kidney stones using advanced intraoperative imaging techniques to reduce perioperative radiation exposure, improve stone-free rates (SFRs), and reduce the number of surgical interventions in a quality improvement project. Patients and Methods: Patients with kidney stones appropriate for percutaneous nephrolithotomy (PCNL) treatment were scheduled into a hybrid operating room for endoscopic surgery (PCNL and/or ureteroscopy) with intent to perform intraoperative CT (ICT). Imaging was performed using an Artis Zeego Care+Clear™ (Siemens) robotic-armed multiplanar fluoroscopy system with collimation to the level of the affected kidney(s). After the initial case, the proprietary CARE™ (combined applications to reduce exposure) protocol was used. When the hybrid room was unavailable, a mobile CT scanner (O-Arm; Medtronics) was used in the traditional room (n = 2). Results: Thirty-one ICTs were performed in 23 consecutive patients during endoscopic stone procedures with a median effective radiation dose of 1.39 mSv per scan, significantly less than the preoperative noncontrast CT (12.02 mSv) in the same patients (p < 0.001). Longitudinal radiation exposure associated with stone treatment significantly decreased by 83% (15.80 to 2.68 mSv, p < 0.001) compared with a similar historical PCNL cohort. Clinically significant residual stones (≥3 mm) were identified at initial ICT in eight patients (35%) and further treated in six patients. One patient had missed residual stone diagnosed 34 days after surgery, which was apparent on re-review of the ICT. Thus, final verified SFR was 87% for all stages. Mean number of procedures improved from 1.77 to 1.30 (p = 0.05) and rate of postoperative CT scans improved from 82% to 26% (p < 0.001). Conclusion: Ultralow-dose ICT was demonstrated to simultaneously improve SFR and number of staged treatments, and greatly reduce the perioperative radiation dose for our patients. The findings support the continued use of this modality to benefit all patients with large stones.

Carbon Dioxide Pyelography: A Convenient and Safe Alternative to Both Room Air and Iodinated Contrast Pyelography During Endourologic Procedures.

Introduction/Background: There are increasing reports of serious complications related to the air pyelography technique, which raise concerns about the safety of room air (RA) injection into the renal collecting system. Carbon dioxide (CO2) is much more soluble in blood than nitrogen and oxygen and thus considerably less likely to cause gas emboli. Iodinated contrast medium (ICM) is expensive, and supplies may not be as reliable as previously assumed. CO2 pyelography (CO2-P) techniques using standard fluoroscopy and digital subtraction fluoroscopy (CO2 digital subtraction pyelography [CO2-DSP]) are described. Materials and Methods: During the endourologic stone cases, 15 to 20 mL of CO2 gas was typically injected into the renal pelvis through a catheter or sheath. Imaging was usually obtained with endovascular CO2 digital subtraction angiography settings using either a traditional fluoroscopy system (TFS) or robotic arm multiplanar fluoroscopy system (RMPFS) (Artis Zeego Care+Clear®; Siemens). Results: CO2-P was performed in 22 endoscopic stone treatment cases between March 2021 and August 2022, primarily using digital subtraction settings in 20 cases. CO2-DSP overall provided higher quality images of the renal pelvis and collecting system than CO2-P, but with a relatively higher radiation dose. Following a quality intervention, fluoroscopy doses for CO2-DSP cases were decreased by 81% overall. The use of CO2-P avoided fluoroscopic or intraoperative CT (ICT) artifacts seen with intraluminal ICM. Conclusions: CO2-P allows the urologist to obtain imaging of the renal collecting system without ICM and with much lower risk of air embolism compared with RA pyelography. CO2 is a nearly cost-free alternative to ICM. Because CO2 is widely available and the technique is easy to perform, we propose that CO2-P should be favored over traditional air pyelography to improve patient safety.

Evaluation of Piperacillin-Tazobactam for Antibiotic Prophylaxis in Traumatic Grade III Open Fractures.

Background: Broad-spectrum antibiotic agents are sometimes utilized for prophylaxis of Gustilo grade III open fractures. However, this practice is not recommended by current guidelines, and it is unknown how patient outcomes are impacted. This study aimed to determine if prophylaxis with piperacillin-tazobactam (PT) results in different rates of infection versus guideline-concordant therapy (GCT). Patients and Methods: This was a single-center, retrospective cohort study of adult trauma patients with Gustilo grade III open long bone fractures admitted between January 2008 and August 2018. The primary outcome of infection (superficial or deep) at six weeks and secondary outcomes of delayed union, nonunion, Clostridioides difficile, and development of resistant organisms were abstracted from medical records. Guideline-concordant therapy was defined as a first-generation cephalosporin with or without an aminoglycoside. Univariable and multivariable analyses controlling for injury severity score (ISS) were performed. Results: One hundred twenty patients were included; 97 (81%) received PT, 23 (19%) received GCT. Common injury mechanisms were motor vehicle/motorcycle accident (57%) and falls (17%), and a majority involved a lower extremity (65%). Baseline characteristics were similar except higher median ISS in PT (14; interquartile range [IQR], 9-22) versus GCT (9; IQR, 9-14). Guideline-concordant therapy was given for a median of four (range, 2-8) days and PT for six (range, 3-11) days (p = 0.078). On univariable analysis, PT patients had more infections at six weeks (23.7% vs. 4.3%; p = 0.042), but multivariable analysis demonstrated no difference (odds ratio [OR], 5.81; 95% confidence interval [CI], 0.73-46.25; p = 0.096). Patients receiving prophylaxis with PT had a longer median length of stay at 16 days (range, 10-22) versus nine days (range, 4-16). No statistically significant differences in delayed union, non-union, Clostridioides difficile, or development of resistant organisms were observed. Conclusions: Broad-spectrum antibiotic prophylaxis with PT did not improve infection rates compared to GCT, suggesting it may not be warranted.

Changing composition of staghorn calculi.

PURPOSE: The 2005 American Urological Association Guideline on the Management of Staghorn Calculi suggests that metabolic stones are uncommon in the composition of staghorn calculi. We determined the incidence and treatment outcomes of metabolic stones in patients with complete staghorn calculi compared to infection stones in those undergoing percutaneous nephrolithotomy. MATERIALS AND METHODS: We retrospectively analyzed all patients who underwent percutaneous nephrolithotomy for complete staghorn calculi between April 2005 and April 2010. Stone analysis was reviewed to classify stone type as infectious or metabolic. Perioperative characteristics and patient outcomes were compared in relation to stone composition. RESULTS: Of 52 kidneys (48 patients) with complete staghorn calculi 29 (56%) were metabolic and 23 (44%) were infection stones. Stone compositions in the metabolic group were calcium phosphate (55%), uric acid (21%), calcium oxalate (14%) and cystine (10%). Patients with metabolic stones were more likely male (55% vs 17%, p = 0.005) and more likely to have a negative preoperative urinary culture (62% vs 35%, p = 0.05). Patients with metabolic stones had a lower complication rate (p = 0.02), while those with infection stones tended to require additional access and secondary treatment, and to have higher recurrence rates. Multiple urinary metabolic abnormalities were noted in all 13 (48%) patients with metabolic stones who completed evaluation. CONCLUSIONS: In a contemporary cohort of patients, metabolic stones comprised a large proportion of complete staghorn calculi. In our series calcium phosphate was the most common stone composition noted. Metabolic stones should be considered during the evaluation of staghorn calculi, and our results underscore the importance of stone analysis and subsequent metabolic evaluation in these patients.

Comparison of trauma mortality and estimated cancer mortality from computed tomography during initial evaluation of intermediate-risk trauma patients.

BACKGROUND: Computed tomography (CT) is the primary source of nontherapeutic medical radiation exposure. Radiation exposure is associated with an increased risk of cancer mortality. Although the risk of cancer mortality is negligible in comparison with that of trauma mortality in high-risk patients, the balance of risk versus benefit in patients with less severe mechanisms of injury is unknown. METHODS: This observational cohort study using a trauma center registry included blunt trauma patients prospectively triaged to an intermediate risk group (level II). Radiation dose was calculated using average dosage for each CT scan. Age-adjusted attributable radiation risk for cancer mortality was calculated using Biological Effects of Ionizing Radiation VII data. RESULTS: Six hundred forty-two level II trauma patients were analyzed, with a mean age of 43.8 years and a median Injury Severity Score of 8. Patients received a median radiation effective dose of 24.7 mSv in the first 24 hours of medical evaluation. Higher Injury Severity Score was associated with greater total radiation dose. Of the four deaths, all were 80 years or older with intracranial injuries. The estimated risk of cancer death attributable to CT exposure was 0.1%. CONCLUSIONS: The risk of mortality from trauma is six times higher than the estimated risk of radiation-induced cancer mortality in intermediate level trauma patients. The mortality due to trauma is greatest in older patients, suggesting lower clinical suspicion is needed to warrant CT studies in this population. Efforts to reduce radiation exposure to trauma patients should focus on young patients with minor injuries.

Technical and equipment challenges for laparoendoscopic single-site surgery and natural orifice transluminal endoscopic surgery.

Laparoendoscopic single-site surgery (LESS) and natural orifice transluminal endoscopic surgery (NOTES™) are new approaches to minimally invasive surgery. A number of technical challenges need to be overcome and new developments of equipment are required before widespread acceptance of either modality occurs. In this paper we discuss novel approaches and innovations as well as review examples of equipment and platforms that have previously been used for LESS and NOTES. Emphasis is given to urological applications.

Laparoscopy assisted transjejunal ERCP for treatment of pancreaticopleural fistula.

CONTEXT: Pancreaticopleural fistula is a rare complication estimated to occur in 0.5% of the patients with pancreatitis and even extremely rare in surgically altered anatomy (e.g. Roux-en-Y anastomosis) patients. The conventional ERCP is difficult to treat pancreaticopleural fistula in a patient with complex upper GI anatomy because of long anatomical route. CASE REPORT: We represent a case of a 47-year-old female with remote subtotal gastrectomy with Roux-en-Y gastrojejunostomy admitted with recurrent left pleural effusion due to pancreaticopleural fistula. After failed ERCP through the anatomical route, pancreaticopleural fistula was treated successfully with laparoscopy-assisted transjejunal ERCP. CONCLUSION: Laparoscopy-assisted ERCP is a useful modality in patients with surgically altered anatomy.

Survey of medical center employees' willingness and availability to donate blood in support of a civilian warm fresh whole blood program.

OBJECTIVES: In military settings, utilizing warm fresh whole blood (WFWB) was associated with reduced mortality; however, there are multiple challenges for administering WFWB to civilians. The authors aimed to determine barriers to hospital employees emergently donating to civilian WFWB programs. METHODS: We surveyed hospital employee willingness to donate emergently, familiarity with blood donation, and queried baseline demographics. The electronic survey was disseminated to a random sample of employees. Descriptive and univariate analyses were performed. RESULTS: Three thousand surveys were sent; 883 were returned (28 percent). The majority of respondents were female (n = 630, 71 percent). Respondent familiarity with WFWB donation included very/somewhat familiar (n = 381, 43 percent) and somewhat-not/not-at-all familiar (n = 356, 40 percent). Most were definitely or somewhat willing to emergently donate (n = 660, 75 percent). Four hundred and sixty would drive from home to donate (52 percent). The majority worked day-time shifts (n = 754, 85 percent). In regards to donation history, 366 (41 percent) had donated blood more than ten times, but 138 (16 percent) had never donated. Barriers to emergent donation were identified (55 percent), with the most common being childcare responsibilities (n = 242; 27 percent). CONCLUSIONS: Hospital employees are willing to donate WFWB emergently, but program implementation must address donor availability and logistical barriers. Future research should assess feasibility of a civilian WFWB program by determining regulatory challenges, development of a quality system for emergency donations, assessment of optimal workforce structure, potential impact to the general blood inventory, as well as patient and community perspectives regarding untested blood units.

Decreasing pancreatic leak after distal pancreatectomy: saline-coupled radiofrequency ablation in a porcine model.

Despite marked improvements in pancreatic surgery, the high incidence and morbidity of pancreatic leak after resection has remained unchanged. The objective of this study was to evaluate the role of saline-coupled radiofrequency ablation (TissueLink) as an alternative to traditional methods of stump closure in an animal model of distal pancreatectomy. Forty swine were randomized after pancreatic transection and remnant stump was either oversewn in a traditional fashion (control) or treated with the device alone (TissueLink). Animals were killed and necropsied at 3 or 5 weeks postoperatively. Primary endpoints were the development of a pancreatic fistula defined as dye extravasation from the remnant duct, presence of undrained amylase-rich fluid collections/abscess, and greater than threefold drain/serum amylase after the third postoperative day. The incidence of pancreatic leak in the TissueLink group was 5.5 vs 42% in the control group (p = 0.01). There were no differences in operative time or other clinical parameters measured. Histologic analysis of the remnant pancreatic stumps confirmed our results. These data support our hypothesis that saline-coupled radiofrequency ablation leads to obliteration of ducts with a resultant decrease in pancreatic leak and subsequent complications. This technology may play a substantial role in preventing this dreaded complication in the clinical setting.

Captive tiger attack: case report and review of the literature.

Tigers, as well as other large predators, are being held in private settings with increasing frequency. Unregulated private "zoos" are cropping up in many rural and suburban settings across the country. The number of attacks from captive predators also is on the rise. This case highlights the potentially violent and aggressive nature of wild animals held in captivity. Treatment principals and wounding patterns of large cat attacks are emphasized.

A case and review of bowel perforation secondary to metastatic lung cancer.

Gastrointestinal tract perforation (GITP) secondary to metastatic lung cancer is extremely rare. We present a case of small bowel perforation secondary to metastatic lung cancer. The objective of this study was to review the current literature and further characterize the incidence, histology, and risk of GITP secondary to lung cancer metastasis. A Medline search was done to identify all the cases of GITP attributed to metastatic lung cancer reported in the literature. Data was collected and analyzed from a collection of cases in the medical literature since 1960. We identified 98 cases of perforated lung cancer metastasis to the small intestine. Four gastric perforations, three colonic perforations, and one appendiceal perforation were also identified but not analyzed. The mean age was 64.5 years. There was a male predominance of 89 per cent versus 11 per cent female. Perforations occurred most often in the jejunum (53%) followed by ileum (28%). Combined jejunum-ileum lesions accounted for 4 per cent of perforations. No duodenal perforations were reported, though a specific site was not determined in 13 per cent of cases. Small bowel perforations were most often caused by adenocarcinoma (23.7%), squamous cell carcinoma (22.7%), large cell carcinoma (20.6%), and small cell carcinoma (19.6%). The prevalence of small bowel perforation secondary to a given primary lung cancer histology varied by region. The mean survival was 66 days with 50 per cent of patients not surviving past 30 days. Despite a high incidence of lung cancer, small bowel perforation secondary to lung cancer metastasis remains relatively rare. Perforated metastases occur more often in men and are found more commonly in the jejunum. Small bowel perforations are caused most often by adenocarcinoma; however, squamous cell and large cell carcinoma metastases are more likely to result in perforation. Small bowel perforation in this setting has a significant impact on mortality, decreasing 1-year survival to less than 3 per cent.

Comparison of sexual function and quality of life after pelvic trauma with and without Angioembolization.

BACKGROUND: The aim is to study the safety of Angioembolization on long-term sexual function and quality of life. METHODS: IRB approval was gained to review the prospectively collected trauma database as well as prospective questionnaires of patients at least 1 year out from pelvic fractures that occurred between 1996 and 2009. Surveys included the SF36v2, Female Sexual Function Index and the International Index of Erectile Function. Values for each domain were compared between patients treated with AE and 2:1 case-matched control patients as well as between the national norms. Values are presented as percentages or means with 95 % CI. P < 0.05 was considered statistically significant. RESULTS: Thirty Seven cases and 74 matched controls were identified. 42 patients completed the survey. There were 13 cases (12 males), and 29 controls (22 males). There was a higher ISS (Injury Severity Score) (32 vs 27; p = 0.048) in the cases, but no difference in pelvic AIS (Abbreviated Injury Severity Score) (3 vs 3). Both groups scored similarly in the SF36 in all domains, but the entire cohort scored lower than the national norms in the physical functioning (41.9 (37.8-46.0) vs50), role physical (40.9 (36.2-45.7) vs50), body pain 43.8 (40.7-46.9) vs50), role emotional 46.3 (42.8-49.8) vs50), and physical composite score (42.1 (38.0-46.3) vs50). All domains of the sexual function in both questionnaires showed significant impairment in our cohort compared with norms. Male cases had similar scores to the controls. CONCLUSION: Pelvic fractures portend a worse long-term QOL and sexual function than the general population. AE, however, does not have an additive affect to these indices.

Fixed-dose vasopressin compared with titrated dopamine and norepinephrine as initial vasopressor therapy for septic shock.

STUDY OBJECTIVE: To investigate the early blood pressure effects of vasopressin compared with titrated catecholamines as initial drug therapy in patients with septic shock. DESIGN: Retrospective cohort, single-center study. SETTING: Intensive care units at the Mayo Clinic, Rochester, Minnesota. PATIENTS: Fifty, 49, and 51 intensive care patients treated initially with vasopressin, norepinephrine, and dopamine, respectively. INTERVENTION: Patients received either intravenous infusion of fixed-dose vasopressin 0.04 U/minute or titrated infusions of norepinephrine or dopamine for low systemic arterial pressures. MEASUREMENTS AND MAIN RESULTS: Patients treated with vasopressin, norepinephrine, and dopamine were similar in all measured characteristics except for their score on the Acute Physiology and Chronic Health Evaluation (APACHE) III (dopamine > vasopressin, p=0.049), renal comorbidities (dopamine > vasopressin, p=0.03) and baseline mean arterial pressure (MAP) (norepinephrine < vasopressin, p=0.005 or dopamine < vasopressin, p=0.05). In all patients, MAP 1 hour before and 1 hour afte intervention, heart rate, and systolic blood pressure were obtained. No treatment differences were identified in achieving postvasopressin MAP after adjusting for APACHE III score, renal dysfunction, and baseline MAP. In patients receiving vasopressin, 28-day mortality was 52%, similar to those receiving norepinephrine (65%, p=0.28) and dopamine (60%, p=0.53). CONCLUSION: Initial, fixed-dose vasopressin infusions increased MAP to 70 mm Hg or greater at 1 hour in intensive care patients with septic shock, similar to titrated norepinephrine or dopamine. Fixed-dose vasopressin appears appropriate as an alternative agent for hemodynamic support in patients with septic shock.

Adequate or not? A comparison of 24-hour urine studies for renal stone prevention by creatinine to weight ratio.

PURPOSE: The intent of this study was to compare urine parameters between kidney stone formers with low, expected, and high creatinine to weight ratio (Cr/kg) and to discuss implications for treatment. PATIENTS AND METHODS: In this retrospective study, 381 stone formers (205 females and 176 males) with urine collections for nephrolithiasis evaluation were included. Using the first collected sample, patients were grouped into low, expected, and high Cr/kg using sex appropriate reference ranges (15.0-20.0 mg/kg for females and 18.0-24.0 mg/kg for males) and evaluated. RESULTS: Of initial collections, 50.7% were outside the Cr/kg reference range. Median age increased as Cr/kg decreased with 13 years age difference between low (56) and high (43) groups. Body mass index and weight also increased significantly with decreased ratio. No significant difference between groups was found for urine volume, total oxalate, oxalate concentration, pH, and supersaturations of calcium oxalate and uric acid. Total calcium, sodium, citrate, calcium concentration, supersaturation of calcium phosphate, and other parameters significantly increased with increased Cr/kg for the cohort. CONCLUSIONS: To our knowledge, this is the first study to thoroughly evaluate the impact of Cr/kg on urine parameters. Clinicians should be cognizant of limitations of Cr/kg for evaluating collection adequacy. It is especially important to consider Cr/kg when there is potential for undertreatment or overtreatment of patients with abnormal Cr/kg. Studies demonstrating hypercalciuria and high Cr/kg may need to be repeated before starting thiazide diuretics. Further studies are needed to determine how to better interpret urine components that vary with Cr/kg ratio.