Changes In Urine Specific Gravity Research Articles

Ad Libitum Drinking Prevents Body Mass Loss Across Consecutive Workdays in Heat

Hydration practices across consecutive days of heavy-intensity work in heat when fluid is freely available is unknown. Without this information it remains unknown whether hydration modifies heat strain under hot working conditions and whether worker recommendations adequately maintain hydration status. We hypothesized that participants would maintain hydration status including daily percent change in body mass across workdays. Fifteen healthy, unacclimated participants (7 Females, Age: 27±6 y, Body mass: 75.0±14.4 kg, Body fat: 26.6±5.8%) completed three consecutive days (Day 1, Day 2, Day 3) of 4 h of 395±10 W work to a work/rest cycle of 45/15 min in a 36.3±0.8°C, 21±5% relative humidity environment. Participants were offered 237 mL of a sport drink every 20 min to consume ad libitum. Urine flow rate (UFR) was measured before work. Urine specific gravity (USG) and nude body mass were measured before and after work. Thirst and fluid consumption were measured throughout work. USG before work was not different between Day 1 (1.013±0.010) and Day 2 (1.013±0.010, p=0.822), but was greater before work on Day 3 (1.015±0.010, p=0.046) compared to Day 2. Change in USG from before to after work was not different between Day 1 (+0.003±0.008) and Day 2 (+0.000±0.006, p=0.123), but was lower on Day 3 (-0.002±0.006, p=0.021) compared to Day 1, with no difference between Day 2 and Day 3 (p=0.058). Before work body mass was not different across days (p=0.103). Daily percent change in body mass was not different across days (p=0.366, Day 1: 0.53±1.11%, Day 2: 0.18±0.95%, Day 3: 0.18±0.81%), indicating weight gain each day. Sweat rate (p=0.790) and UFR (p=0.469) were not different among days. Participants consumed 77±18% (Day 1), 82±19% (Day 2), and 82±16% (Day 3) of fluid offered (p=0.401), equaling 31±10 mL/kg (Day 1), 33±11 mL/kg (Day 2), 33±10 mL/kg (Day 3) (p=0.370). Maximum thirst was greater on Day 1 (3.5±1.1) compared to Day 3 (2.9±1.0, p=0.045) with no difference between Day 1 and Day 2 (3.4±1.4, p=0.648) or between Day 2 and Day 3 (p=0.121). This study demonstrates consistent hydration practices and no differences in hydration status across three consecutive days of high-intensity work in heat when fluid is freely available. Under these conditions, workers can consume fluids ad libitum and worker recommendations for hydration during heat stress should be revisited. This project was funded my the National Institute for Occupational Safety and Health (1K01OH012016-01A1). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sex Differences in Hydration Biomarkers and Test-Retest Reliability Following Passive Dehydration.

This study investigated (a)differences between males and females for changes in serum, tear, and urine osmolality, hematocrit, and urine specific gravity following acute passive dehydration and (b)assessed the reliability of these biomarkers separately for each sex. Fifteen males (age: 26.3 ± 3.5years, body mass: 76 ± 7kg) and 15 females (age: 28.8 ± 6.4years, body mass: 63 ± 7kg) completed a sauna protocol twice (5-28days apart), aiming for 4% body mass loss (BML). Urine, blood, and tear markers were collected pre- and postdehydration, and change scores were calculated. Male BML was significantly greater than that of females in Trial 1 (3.53% ± 0.55% vs. 2.53% ± 0.43%, p < .001) and Trial 2 (3.36% ± 0.66% vs. 2.53% ± 0.44%, p = .01). Despite significant differences in BML, change in hematocrit was the only change marker that displayed a significant difference in Trial 1 (males: 3% ± 1%, females: 2% ± 1%, p = .004) and Trial 2 (males: 3% ± 1%, females: 1% ± 1%, p = .008). Regression analysis showed a significant effect for sex (male) predicting change in hematocrit (β = 0.8, p = .032) and change in serum osmolality (β = -3.3, p = .005) when controlling for BML but not for urinary or tear measures. The intraclass correlation coefficients for females (ICC 2, 1) were highest for change in urine specific gravity (ICC = .62, p = .006) and lowest for change in tear osmolarity (ICC = -.14, p = .689), whereas for males, it was posthematocrit (ICC = .65, p = .003) and post tear osmolarity (ICC = .18, p = .256). Generally, biomarkers showed lower test-retest reliability in males compared with females but, overall, were classified as poor-moderate in both sexes. These findings suggest that the response and reliability of hydration biomarkers are sex specific and highlight the importance of accounting for BML differences.

Urine concentrating ability in cats with hyperthyroidism: Influence of radioiodine treatment, masked azotemia, and iatrogenic hypothyroidism.

Hyperthyroid cats often have urine specific gravity (USG) values <1.035. It remains unclear how USG changes after treatment, if USG can be used to predict azotemia after treatment, or how iatrogenic hypothyroidism influences USG values. To determine the proportion of hyperthyroid cats with USG <1.035 vs ≥1.035; if USG changes after treatment; and whether USG <1.035 correlated with unmasking of azotemia or hypothyroidism. Six hundred fifty-five hyperthyroid cats treated with radioiodine; 190 clinically normal cats. Prospective, before-and-after study. Hyperthyroid cats had serum thyroxine, thyroid-stimulating hormone, and creatinine concentrations, and USG measured before and 6 months after successful treatment with radioiodine. Of untreated hyperthyroid cats, USG was ≥1.035 in 346 (52.8%) and <1.035 in 309 (47.2%). After treatment, 279/346 (80.6%) maintained USG ≥1.035, whereas 67/346 (19.4%) became <1.035; 272/309 (88%) maintained USG <1.035, whereas 37/309 (12%) became ≥1.035. Only 22/346 (6.4%) with USG ≥1.035 developed azotemia after treatment, compared with 136/309 (44%) with <1.035 (P < .001). Of cats remaining nonazotemic, 38% had USG <1.035, compared with 20% of normal cats (P < .001). The 137 cats with iatrogenic hypothyroidism had lower USG after treatment than did 508 euthyroid cats (1.024 vs 1.035), but USGs did not change after levothyroxine supplementation. USG <1.035 had high sensitivity (86.1%) but moderate specificity (65.2%) in predicting azotemia after treatment. Hyperthyroidism appears not to affect USG in cats. However, cats with evidence of sub-optimal concentrating ability before radioiodine treatment (USG < 1.035) are more likely to develop azotemia and unmask previously occult chronic kidney disease. Iatrogenic hypothyroidism itself did not appear to affect USG values.

A Pilot Randomized Trial to Compare Polyuria and Polydipsia during a Short Course of Prednisolone or Methylprednisolone in Dogs with Atopic Dermatitis.

Simple SummaryGlucocorticoids (a.k.a. steroids) are often used to treat allergic skin diseases in dogs, but they commonly cause side-effects, such as increased drinking (polydipsia) and urination (polyuria). Veterinarians have long believed that the steroid methylprednisolone causes less drinking and urination than prednisolone. We performed a clinical trial in which dogs with atopic dermatitis were treated either with prednisolone or methylprednisolone at the beginning of an elimination diet. After two weeks, the owners did not notice any significant increase in drinking. Most dogs had a reduction in the specific gravity (that is the density) of the urine, which signals a more diluted and abundant urine, but there was no significant difference between the two steroids for urine dilution. In conclusion, there were no significant changes in either drinking and urine dilution when giving prednisolone or methylprednisolone to allergic dogs for two weeks. A longer treatment duration or higher doses might give different results, however.Glucocorticoids are widely used to treat canine allergic disorders, but they frequently cause polyuria and polydipsia (PUPD). At equipotent dosages, oral methylprednisolone is believed to cause less PUPD than prednisolone. We performed a pilot randomized, open, parallel trial with 22 dogs with nonseasonal AD receiving either prednisolone or methylprednisolone at equipotent dosages, once daily for 14 days during the first phase of a restriction–provocation dietary trial. Before and on days 3, 7, and 14 after starting the glucocorticoids, owners estimated water consumption for 24 h. On the same days and before the glucocorticoid was given, owners collected the first-morning urine to determine the urine specific gravity (USG). There were no significant differences between the prednisolone and methylprednisolone groups on days 3, 7, and 14 when comparing the changes in water intake from baseline. Most dogs from both groups exhibited a slight reduction in USG during the study. Still, there was no significant difference in USG changes between the groups on any of these three reevaluation days. In conclusion, the administration of two weeks of oral prednisolone and methylprednisolone at equipotent anti-inflammatory dosages at the beginning of an elimination diet did not lead to significant differences in water intake and USG.

Habit or lack of education? Hypohydration is present in elite senior judo athletes even during a weight-stable training camp

It has been well-documented that high-level judo athletes presented a high level of hypohydration during weight-cutting and competition periods. However, there is a lack of studies investigating the hydration status of high-level judo athletes during a weight-stable training period. Therefore, this study aimed to investigate elite judo athletes’ hydration status, body mass change, and fluid intake during a weight-stable training camp. Twenty-seven judo athletes (women n = 8, men n = 19, body weight = 79.6 ± 20.9 kg) from the senior national judo team voluntarily participated in this study. Data were collected in the morning after waking up and before and after the morning and evening training sessions. On the second day, the measurements were taken again in the morning after waking up. Urine-specific gravity (USG) was classified as hydrated (USG &lt; 1.020) and hypohydrated (USG ≥ 1.020). The athletes’ USG values measured on two consecutive mornings increased (1.025 ± 0.007 to 1.029 ± 0.006) during 24 h, in which athletes performed judo training in the morning and evening. Moreover, sex and weight category did not affect the changes in USG values ( p &gt; .05). Most of the elite judo athletes presented hypohydration (92.6%). The relationship between the fluid intake of the athletes and the changes in USG and body weight values during 24 h was not significant ( p &gt; .05). The current study’s findings revealed that high-level judo athletes present a high level of hypohydration even during a weight-stable training camp. Furthermore, the training sessions during the experiment period (24 h) worsened the hydration status of the senior athletes in all weight categories for both women and men.

Workers' health and productivity under occupational heat strain: a systematic review and meta-analysis

Occupational heat strain (ie, the effect of environmental heat stress on the body) directly threatens workers' ability to live healthy and productive lives. We estimated the effects of occupational heat strain on workers' health and productivity outcomes. Following PRISMA guidelines for this systematic review and meta-analysis, we searched PubMed and Embase from database inception to Feb 5, 2018, for relevant studies in any labour environment and at any level of occupational heat strain. No restrictions on language, workers' health status, or study design were applied. Occupational heat strain was defined using international health and safety guidelines and standards. We excluded studies that calculated effects using simulations or statistical models instead of actual measurements, and any grey literature. Risk of bias, data extraction, and sensitivity analysis were performed by two independent investigators. Six random-effects meta-analyses estimated the prevalence of occupational heat strain, kidney disease or acute kidney injury, productivity loss, core temperature, change in urine specific gravity, and odds of occupational heat strain occurring during or at the end of a work shift in heat stress conditions. The review protocol is available on PROSPERO, registration number CRD42017083271. Of 958 reports identified through our systematic search, 111 studies done in 30 countries, including 447 million workers from more than 40 different occupations, were eligible for analysis. Our meta-analyses showed that individuals working a single work shift under heat stress (defined as wet-bulb globe temperature beyond 22·0 or 24·8°C depending on work intensity) were 4·01 times (95% CI 2·45-6·58; nine studies with 11 582 workers) more likely to experience occupational heat strain than an individual working in thermoneutral conditions, while their core temperature was increased by 0·7°C (0·4-1·0; 17 studies with 1090 workers) and their urine specific gravity was increased by 14·5% (0·0031, 0·0014-0·0048; 14 studies with 691 workers). During or at the end of a work shift under heat stress, 35% (31-39; 33 studies with 13 088 workers) of workers experienced occupational heat strain, while 30% (21-39; 11 studies with 8076 workers) reported productivity losses. Finally, 15% (11-19; ten studies with 21 721 workers) of individuals who typically or frequently worked under heat stress (minimum of 6 h per day, 5 days per week, for 2 months of the year) experienced kidney disease or acute kidney injury. Overall, this analysis include a variety of populations, exposures, and occupations to comply with a wider adoption of evidence synthesis, but resulted in large heterogeneity in our meta-analyses. Grading of Recommendations, Assessment, Development and Evaluation analysis revealed moderate confidence for most results and very low confidence in two cases (average core temperature and change in urine specific gravity) due to studies being funded by industry. Occupational heat strain has important health and productivity outcomes and should be recognised as a public health problem. Concerted international action is needed to mitigate its effects in light of climate change and the anticipated rise in heat stress. EU Horizon 2020 research and innovation programme.

The Effect of Water Loading on Acute Weight Loss Following Fluid Restriction in Combat Sports Athletes.

Novel methods of acute weight loss practiced by combat sport athletes include "water loading," the consumption of large fluid volumes for several days prior to restriction. We examined claims that this technique increases total body water losses, while also assessing the risk of hyponatremia. Male athletes were separated into control (n = 10) and water loading (n = 11) groups and fed a standardized energy-matched diet for 6 days. Days 1-3 fluid intake was 40 and 100ml/kg for control and water loading groups, respectively, with both groups consuming 15ml/kg on Day 4 and following the same rehydration protocol on Days 5 and 6. We tracked body mass (BM), urine sodium, urine specific gravity and volume, training-related sweat losses and blood concentrations of renal hormones, and urea and electrolytes throughout. Physical performance was assessed preintervention and postintervention. Following fluid restriction, there were substantial differences between groups in the ratio of fluid input/output (39%, p < .01, effect size = 1.2) and BM loss (0.6% BM, p = .02, effect size = 0.82). Changes in urine specific gravity, urea and electrolytes, and renal hormones occurred over time (p < .05), with an interaction of time and intervention on blood sodium, potassium, chloride, urea, creatinine, urine specific gravity, and vasopressin (p < .05). Measurements of urea and electrolyte remained within reference ranges, and no differences in physical performance were detected over time or between groups. Water loading appears to be a safe and effective method of acute BM loss under the conditions of this study. Vasopressin-regulated changes in aquaporin channels may potentially partially explain the mechanism of increased body water loss with water loading.

Spot Sample Urine Specific Gravity Does Not Accurately Represent Small Decreases in Plasma Volume in Resting Healthy Males

ABSTRACTBackground: Urine specific gravity (USG) is often used to assess hydration status, particularly around athletic competition, but it is unknown whether high USG is indicative of plasma volume (PV) reduction (i.e., hypohydration). We tested the hypothesis that if high USG is reflective of reduced PV, subsequent fluid ingestion would increase PV.Purpose: The purpose of this study was to examine 24-hour changes in USG and PV in individuals presenting with high and low spot USG.Methods: Nineteen healthy males were provided food and water over 24 hours with a total water volume of 35 ml·kg−1 body mass. Absolute PV and blood volume (BV), measured using the CO-rebreathe technique, along with USG were measured before and after a 24-hour intervention period. Based on a preintervention morning spot USG, subjects were post hoc assigned to groups according to USG (≤1.020 or >1.020; low and high USG, respectively).Results: Despite presenting with an elevated spot USG (1.026 ± 0.004), subsequent fluid ingestion over 24 hours did not lead to changes (∆) in PV (−75 ± 234 ml) or BV (−156 ± 370 ml) in the high USG group (p > 0.05). However, a spot USG after the 24-hour intervention in this group decreased (p = 0.018) to a level indicating improved hydration status (1.017 ± 0.007). In the low USG group, there were no changes in PV (−39 ± 274 ml), BV (−82 ± 396 ml), or USG (0.003 ± 0.007) over the 24-hour fluid intervention (all p > 0.05).Conclusions: Despite a high preintervention USG and subsequent decrease after 24-hour fluid intake, measures of PV and BV were not indicative of this seemingly improved hydration status. This suggests that a highly concentrated spot sample USG and subsequent changes are not accurately representative of PV or BV.

Factors Associated with Postoperative Diabetes Insipidus after Pituitary Surgery.

BackgroundDetermining risk factors for diabetes insipidus (DI) after pituitary surgery is important in improving patient care. Our objective is to determine the factors associated with DI after pituitary surgery.MethodsWe reviewed records of patients who underwent pituitary surgery from 2011 to 2015 at Philippine General Hospital. Patients with preoperative DI were excluded. Multiple logistic regression analysis was performed and a predictive model was generated. The discrimination abilities of the predictive model and individual variables were assessed using the receiving operator characteristic curve.ResultsA total of 230 patients were included. The rate of postoperative DI was 27.8%. Percent change in serum Na (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.15 to 1.69); preoperative serum Na (OR, 1.19; 95% CI, 1.02 to 1.40); and performance of craniotomy (OR, 5.48; 95% CI, 1.60 to 18.80) remained significantly associated with an increased incidence of postoperative DI, while percent change in urine specific gravity (USG) (OR, 0.53; 95% CI, 0.33 to 0.87) and meningioma on histopathology (OR, 0.05; 95% CI, 0.04 to 0.70) were significantly associated with a decreased incidence. The predictive model generated has good diagnostic accuracy in predicting postoperative DI with an area under curve of 0.83.ConclusionGreater percent change in serum Na, preoperative serum Na, and performance of craniotomy significantly increased the likelihood of postoperative DI while percent change in USG and meningioma on histopathology were significantly associated with a decreased incidence. The predictive model can be used to generate a scoring system in estimating the risk of postoperative DI.

Fluid balance of Olympic male basketball players before and during performance (633.4)

Fluid balance of Olympic male basketball players was assessed prior to and throughout performance and possible relationships between hydration status and physical load were examined during three pre‐Olympic basketball games. Pre‐ and post‐game urine specific gravity (USG) and body weight as well as fluid intake during the games were determined. Physical load was assessed by accelerometry/GPS (MinimaxX, Catapult). Overall, 54% of players were hypohydrated entering at least one of three games. Forty percent in Games 1 and 2 and 67% of players in Game 3 lost 蠅1% of body mass. No associations were detected between fluid intake and hydration or physical load. Negative correlations were observed for pre‐game USG and late game physical load (Q3: r=‐.603, p&lt;.039; Q4: r=‐.909, p&lt;.034). Pre‐game USG was not related to fluid intake during the game. A negative correlation existed between USG change and physical load (r=‐.627, p&lt;.023) when all games were averaged. These data suggest that poor pre‐game hydration may be related to late game fatigue and that dehydration during play as evidenced by change in USG is related to lower physical load. Voluntary fluid intake failed to compensate for a poor pre‐game USG.

Renal effects of carprofen and etodolac in euvolemic and volume-depleted dogs

To determine the effects of carprofen and etodolac on renal function in euvolemic dogs and dogs with extracellular fluid volume depletion induced via administration of furosemide. 12 female Beagles. Dogs received a placebo, furosemide, carprofen, etodolac, furosemide and carprofen, and furosemide and etodolac. The order in which dogs received treatments was determined via a randomization procedure. Values of urine specific gravity, various plasma biochemical variables, glomerular filtration rate (GFR [urinary clearance of creatinine]), and renal plasma flow (urinary clearance of para-aminohippuric acid) were determined before and after 8 days of drug administration. A washout time of approximately 12 days was allowed between treatment periods. Administration of furosemide, furosemide and carprofen, and furosemide and etodolac caused changes in urine specific gravity and values of plasma biochemical variables. Administration of carprofen or etodolac alone did not have a significant effect on renal plasma flow or GFR. Concurrent administration of furosemide and carprofen or furosemide and etodolac caused a significant decrease in GFR. After 12-day washout periods, mean values of GFR were similar to values before drug administration for all treatments. Results indicated GFR decreased after 8 days of concurrent administration of furosemide and carprofen or furosemide and etodolac to dogs. Administration of preferential cyclooxygenase-2 inhibitors to dogs with extracellular fluid volume depletion or to dogs treated with diuretics may transiently impair renal function.

Acetate containing sports beverages appear to alter buffering capacity during endurance exercise in trained male athletes

Methods Trained male cyclists (n=11;24.3 ± 0.6 years; VO2MAX:54.9 ± 2.7ml/kg/min)consumed isocaloricsports beverages containing citric acid (placebo), triacetin (TRI), or acetic acid (AA)in a double-blind, randomized, controlled crossover study. Subjects consumed 710 mLbeverage anda standard breakfastbeginning each test day. Subjects performed two 30 second Wingate cycle tests separated by 4 minutes and consumed 7.5 ml/kg beveragewhile resting during a 60-min recovery period. Subjects then cycled for three 15-min consecutive segments at 65% VO2MAX followed by a 15-min simulated “time trial.” Three ml/kg beverage was consumed during the endurance cycle test. Plasma glucose and lactate; serum free fatty acids, sodium, potassium, chloride, bicarbonate, osmolality; whole blood pH, urine osmolality and specific gravity were obtained at timesthroughout the day to assess markers of metabolism, and respiratory and cardiovascular variables were assessed during the time trial. Data were analyzed using repeated measures analysis of variance including subject and treatment as factors; Tukey’s test was used for pairwise comparisons. Data are presented as means ± SEM and p 0.05). Minute ventilation was reduced with AAafter segment 3(p = 0.03), and triacetin (p = 0.08) versus control. Acetic acid consumption tended to reduce total work versus placebo (p = 0.06) during the time trial. There were no significant changes in urine specific gravity, urine osmolality levels, total urine volume, or net fluid loss throughout the day (p> 0.05).

Relationship Between Changes in Upon-Waking Urinary Indices of Hydration Status and Body Mass in Adolescent Singaporean Athletes

This study investigated the relationship between changes in upon-waking body mass (BM) and changes in urine specific gravity (U(sg)) and urine color (U(col)) from 1 day to the next. Throughout the 5-day investigation, healthy adolescent Singaporean athletes (n = 66) had their upon-waking, bladder-voided BM measured. A small aliquot of the first bladder void each day was collected and analyzed for U(sg) and U(col), the latter by both an investigator (IU(col)) and individual participants (SU(col)). Results revealed a significant inverse relationship between changes in BM and changes in U(sg) (p = .003) and U(col) (p = .001). On average, U(sg) and U(col) changed by ~0.003 units and ~1 color (across a 9-unit scale), respectively, with every 1% change in BM from 1 day to the next. There was a stronger relationship between U(sg) and IU(col) (r = .82, p < .001) than between U(sg) and SU(col) (r = .60, p < .001). These results suggest that the degree of fluid deficit may be predicted from the U(sg) measurements among moderately hypohydrated athletes. In addition, training athletes to interpret and use the U(col) chart is recommended.

Impact of Bolus versus Metered Fluid Consumption on Urine Specific Gravity and Urine Color

PURPOSE: This study assessed urine specific gravity (USG) and urine color (UC) as measures of hydration status (compared to body mass changes) following bolus and metered rehydration. METHODS: Subjects (n=8) exercised in a climate controlled chamber (35°C, 55% RH) until a 2% loss of body weight was obtained. In 4 separate trials, fluids (water and a carbohydrate-electrolyte beverage) were replaced using bolus (100% volume replacement within 1hr) and metered (12.5% of total volume every 30 minutes for 4 hrs) administrations. Urine was collected as produced for 8 hours following dehydration. USG, UC, and urine volumes were measured for each void. RESULTS: Pearson and Spearman correlations revealed weak relationships (r = 0.01 to r = 0.34) between changes in % hydration measured by body weight and USG, and UC, regardless of administration techniques or recovery beverages used; however, correlations between USG and UC varied from r = 0.63 to 0.86. CONCLUSIONS: Whereas changes in USG and UC tracked well with one another, these data suggest that these urinary markers may be limited in value when used to track hydration status in less than 2% hypohydrated healthy ambulatory people.

The Timing of Fluid Intake during an Olympic Distance Triathlon

Seven highly trained male triathletes, aged 18 to 35 years, were tested during two simulated Olympic distance triathlons to determine whether run performance was enhanced when consuming 177 ml of water at 8, 16, 24, and 32 kilometers (Early Trials) compared to consumption at 10, 20, 30, and 40 kilometers (Late Trials), during the cycling segment of the triathlon. Swim times for 1500 m were similar between trials; 40-km cycling times were approximately 10 s faster during the Late Trials; however, 10-km run times were faster during the Early Trials (P < 0.02). No significant differences between run trials were found for the rating of perceived exertion, oxygen uptake, heart rate, and change in urine specific gravity. It was concluded that the consumption of fluids earlier in the cycle phase of the Olympic distance triathlon benefits the run and overall performance time.

THE EFFECT OF A COMPETITIVE WRESTLING SEASON ON BODY WEIGHT,HYDRATION, AND MUSCULAR PERFORMANCE IN COLLEGIATE WRESTLERS

The purpose of the present investigation was to examine the effects of a collegiate wrestling season on body weight, hydration, and muscular performance. Twelve Division I collegiate wrestlers (mean ± SE; 20.75 ± 0.41 year) volunteered to participate in testing sessions during midseason and 3 weeks following the season. Testing consisted of weigh-in, providing a urine sample for hydration analysis, and a measure of isometric leg extension peak torque. Weight significantly increased (p < 0.05) following the completion of the competitive season. No significant change in urine specific gravity (p > 0.05) was observed. Muscular performance was affected by the season as peak torque (PT) and PT-to-body weight ratio increased significantly (p < 0.05). Following the collegiate wrestling season, augmentation in body weight and muscular performance of the wrestlers occurs without alterations in hydration status. Further research is warranted on what type of strength training program would most effectively reduce the decrements in strength associated with weight loss and the strain of a competitive season.

Diuretic effects of fenoldopam in healthy cats

AbstractObjective: To determine the effect of fenoldopam infusion on urine output, sodium excretion, creatinine clearance, and indirect blood pressure in healthy cats.Design: Prospective study.Setting: Veterinary medical teaching hospital.Animals: Eight purpose‐bred cats, 2–4 years old.Interventions: None.Measurements: Urine output was measured hourly for 12 hours before and after fenoldopam administration. Sodium excretion, modified creatinine clearance, and fractional sodium excretion were measured before and following fenoldopam administration. Urine specific gravity, central venous pressure, and systolic blood pressure were measured every 4 hours during the experiment.Main results: Compared with pre‐infusion values, urine output, sodium excretion, and fractional excretion of sodium increased significantly 6 hours after initiation of fenoldopam infusion. This increase was sustained throughout the observation period. The modified creatinine clearance decreased significantly following 2 hours of fenoldopam infusion, but increased significantly by 6 hours after infusion, the time of peak urine output. Changes in urine specific gravity mirrored changes in fractional sodium excretion, whereas the central venous pressure mirrored changes in modified creatinine clearance. The diuretic effect in cats was prevented when a dopamine receptor blocking agent was administered before fenoldopam infusion.Conclusion: Fenoldopam at a dose of 0.5 μg/kg/min induces diuresis in cats in a delayed manner. This increase appears to be due, in part, to dopamine receptor‐induced natriuresis. Changes in glomerular filtration rate may also occur.

Sweat Rate, Fluid Consumption, and Hydration Indices for Youth Soccer Players

PURPOSE: Previous research has shown that youth participating in sports camps begin hypohydrated and display inadequate hydration during camp. The purposes of this study were to measure sweat rate (SR), fluid consumption (FC), and various hydration indices and to use this information as tools to educate youth soccer players about hydration status. METHODS: Thirty-three boys and 17 girls (50.2±9.4 kg, 159.1±7.2 cm, 13±0.9 yrs, and 8±2 yrs soccer experience) volunteered to participate as part of a summer soccer camp in which they practiced 2–3 times per day for 5 consecutive days. Subjects were randomly assigned to non-intervention (NI) or educational intervention (EI) and grouped as younger (10–13 yrs) or older (14–17 yrs) at camp registration. EI took place in the evening on days 2–4 and lasted for approx. 5 min in groups of 2–3. SR, FC during practice, and various hydration indices were used as educational tools. SR was calculated from body weight (BW) taken immediately before practice and immediately post practice, while correcting for FC. Urine sample and BW were obtained before breakfast (AM) and before dinner (PM) each day. RESULTS: SR (1/hr) was greater in males vs females (1.01±0.31 vs 0.69±0.21, respectively) and older vs younger (1.10±0.31 vs 0.77±0.25, respectively). Older males and females had sweat rates of 1.17±0.23 and 0.69±0.56 l/hr, respectively. Younger males and females had sweat rates of 0.84±0.30 and 0.68±0.15 l/hr, respectively. FC (l/hr) during practice was greater for males than females (0.81 vs 0.69, p=0.015), and no differences existed between older and younger (0.91 vs 0.64, p=0.185). A higher rate of FC did not compensate for increased SR in males compared to females, so they became more dehydrated during practice (−0.56 vs 0.06 %BW loss, respectively). Of the 60.4% that lost weight during practice, 30.9% lost >1% BW. EI had no effect on SR or FC (p>.05). Average urine specific gravity (USG) was lower in EI than NI for males (p=0.007) and younger (p=0.045). USG changes from AM to PM increased as the week progressed (p=0.019), but EI failed to reverse this trend (p>.05). Changes in urine osmolality from PM to AM of the next day showed tendencies for EI subjects to have improved rehydration compared to NI (−39 vs +42 mOsm/kg·H2O, respectively). CONCLUSIONS: FC and SR, although rarely measured in the field, were similar to published lab findings. Although FC closely matched SR for all groups, the subjects remained chronically dehydrated during camp. EI may influence the hydration status of males and females and younger and older soccer players. Future studies with EI need to further emphasize hydration when not exercising.

The Effect of a Competitive Wrestling Season on Body Weight, Hydration, and Muscular Performance in Collegiate Wrestlers

The purpose of the present investigation was to examine the effects of a collegiate wrestling season on body weight, hydration, and muscular performance. Twelve Division I collegiate wrestlers (mean +/- SE; 20.75 +/- 0.41 year) volunteered to participate in testing sessions during midseason and 3 weeks following the season. Testing consisted of weigh-in, providing a urine sample for hydration analysis, and a measure of isometric leg extension peak torque. Weight significantly increased (p < 0.05) following the completion of the competitive season. No significant change in urine specific gravity (p > 0.05) was observed. Muscular performance was affected by the season as peak torque (PT) and PT-to-body weight ratio increased significantly (p < 0.05). Following the collegiate wrestling season, augmentation in body weight and muscular performance of the wrestlers occurs without alterations in hydration status. Further research is warranted on what type of strength training program would most effectively reduce the decrements in strength associated with weight loss and the strain of a competitive season.

Management of fluid and electrolyte therapy in the newborn.

The fluid balance can be monitored with a system that is fairly simple but requires meticulous collection of patient data. Appropriate organization of this data into a tabulated form, and daily interpretation of these data is given in Table X. The pertinent data includes previous fluid and electrolyte balance, intake, output, trends in changes in urine specific gravity, changes in body weight, serum electrolytes, calcium phosphorus, blood gases, and vital signs. It should be emphasized that the goal of fluid balance in the first week of life is to achieve a negative balance with an anticipated weight loss of approximately 10% during the first week of life. This allowance for 1 to 2% per day of weight loss and 1–1.5 mEq/day of sodium loss during the first week of life is essential specifically in premature and sick infants to avoid overload or dehydration.