INTRODUCTION: Microgravity exposure unloads the skeleton. This increases urinary calcium excretion, which reflects both increased bone loss and kidney stone formation risk. We studied the probability that first morning void (FMV) urinary calcium (Uca) measurements would capture the highest Uca concentration in a day.METHODS: For 8 wk, three men and three women collected void-by-void 24-h urine samples weekly. Uca concentration was analyzed using a calcein-based system. Uca concentrations were ranked among all samples from each person. FMV and non-FMV (nFMV) Uca concentrations were compared with a Mann Whitney U-test. The probability that an FMV would capture the highest Uca concentration in a day was assessed.RESULTS: Among 377 voids collected, 46 were FMV and 331 were nFMV. Among all samples, the Uca concentration for FMV was significantly higher than nFMV (P < 0.0001). Out of the 46 FMVs, 24 were highest in Uca concentration for the corresponding 24-h period, giving a 52.2% probability that any given FMV would capture the highest Uca concentration in a day. The probability of measuring the highest Uca concentration from at least 1 d increased to 77.1%, and 89.1% when two or three FMVs were collected respectively.DISCUSSION: Acquiring 2–3 repeated FMVs provides a high likelihood of capturing the highest Uca from a day. This suggests repeated first morning void Uca concentrations could assess the risk of bone loss and kidney stone formation, which may provide ability for real-time implementation of countermeasure programs to prevent bone and renal complications in prolonged spaceflight.Thamer S, Buckey JC. First void urinary calcium for tracking bone loss and kidney stone risk in space. Aerosp Med Hum Perform. 2022; 93(7):546–550.

Introduction Sleep Apnea (SA) is a common sleep disorder that increases postoperative morbidity. There is limited research on how SA influences outcomes following operative fixation of ankle fractures. Therefore, the aim of this study was to determine whether patients who undergo surgical fixation for bimalleolar ankle fractures have higher rates of medical complications and health care expenditures. Methods A retrospective review from January 1, 2005 to March 31, 2014 was conducted using the parts A and B Medicare Data from PearlDiver database. Patients with and without SA on the day of the primary open reduction and internal fixation (ORIF) of their bimalleolar ankle fractures were queried using the International Classification of Diseases, Ninth Revision codes. Welch’s t-tests were used to compare costs of care. A multivariate binomial logistic regression model was used to calculate the odds ratio (OR) of adverse events. A P-value <.001 was considered statistically significant. Results There were 20 560 patients (SA = 3150; comparison cohort = 17 410) who underwent ORIF for bimalleolar ankle fractures during the study period. Sleep apnea patients were found to have significantly higher rates and odds of 90-day medical complications (21.42% vs 7.47%, OR: 3.11, P < .0001) and 90-day costs of care ($7213.12 vs $5415.79, P < .0001). Conclusion This research demonstrates an increased risk of postoperative medical complications and health care costs among patients with SA undergoing ORIF for bimalleolar ankle fractures. Level of Evidence Therapeutic, Level IV: Retrospective

Purpose of reviewWeightlessness increases both bone loss and kidney stone formation risk. The large interior volume of the International Space Station (ISS) has allowed for a mix of exercise devices to help maintain the skeleton. But space exploration is changing. Long stays on the ISS will be replaced by journeys in smaller spacecraft both to and around the Moon. Small private space stations are under development. This will limit the ability to do exercise countermeasures, which can increase both bone loss and kidney stone risk. This review examines this risk and how it can be minimized in this new era of spaceflight. Recent findingsSimple, low-mass, low-power ways to track bone loss and kidney stone risk in space are being researched. Tracking urinary calcium concentration in the first morning void and targeting additional countermeasures (e.g. bisphosphonates) to those who run consistently high levels is one promising approach. SummaryNew exploration spacecraft would not have the room and capability to replicate the current 2 h, daily exercise countermeasure programme on the ISS. A monitoring approach, perhaps using urinary calcium as a marker, is needed to find those at greatest risk. This would allow countermeasures to be targeted individually and used efficiently.

INTRODUCTION: Microgravity-induced bone loss increases urinary calcium excretion which increases kidney stone formation risk. Not all individuals show the same degree of increase in urinary calcium and some pre-flight characteristics may help identify individuals who may benefit from in-flight monitoring. In weightlessness the bone is unloaded, and the effect of this unloading may be greater for those who weigh more. We studied whether pre-flight body weight was associated with increased in-flight urinary calcium excretion using data from Skylab and the International Space Station (ISS). METHODS: A retrospective analysis of Skylab and ISS data was conducted. The study was reviewed and approved by the National Aeronautics and Space Administration (NASA) electronic Institutional Review Board (eIRB) and data were sourced from the Longitudinal Study of Astronaut Health (LSAH) database. The effect of weight on urinary calcium excretion was examined using linear mixed effect models with day-in-flight, weight, and program (Skylab or ISS) as fixed effects and the subject’s responses over time as random effects. RESULTS: The combined Skylab and ISS data included 45 participants (9 Skylab, 36 ISS). Both weight and day in flight were positively related to urinary calcium excretion. There was also an interaction between weight and day in flight with higher weight associated with higher calcium excretion earlier in the mission. DISCUSSION: Several factors can affect urinary calcium excretion in space including baseline urinary calcium excretion, dietary intake, and genetic makeup. This study shows that pre-flight weight is also a factor and could be included in the risk assessments for bone loss and kidney stone formation in space.