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PubMed2000

Urinary protein and albumin excretion corrected by creatinine and specific gravity.

Timed urine collections are difficult to use in clinical practice owing to inaccurate collections making calculations of the 24-h albumin or protein excretion questionable. One of our goals was to assess the 'correction' of urinary albumin and (or) protein excretion by dividing these by either the creatinine concentration or the term, (specific gravity-1)x100(1). The 24-h creatinine excretion can be estimated based on the patients' gender, age and weight. We studied the influence of physiological extremes of hydration and exercise, and protein and creatinine excretion in patients with or suspected kidney disorders. Specimens were collected from healthy volunteers every 4 h during one 24-h period. We assayed the collections individually to give us an assessment of the variability of the analytes with time, and then reassayed them after combining them to give a 24-h urine. For all volunteers, the mean intra-individual CVs based on the 4-h collections expressed in mg/24 h were 80.0% for albumin and 96.5% for total protein (P0.2). The CVs were reduced by dividing the albumin or protein concentration by the creatinine concentration or by the term, (SG-1)x100. This gave a CV for mg albumin/g creatinine of 52% (P<0.1 vs. albumin mg/g creatinine); mg protein/g creatinine of 39% (P<0.05 vs. mg protein/g creatinine); mg albumin/[(SG-1)x100] of 49% (P<0.1 vs. albumin)/[(SG-1)x100]; and mg protein/[(SG-1)x100] of 37% (P<0. 05 vs. mg protein)/[(SG-1)x100]. For the 68 subjects in the study, the strongest correlation was between the creatinine concentrations and the 24-h urine volume: r=0.786, P<0.001. The correlation of (SG-1)x100 vs. the 24-h urine volume was: r=0.606, P<0.001; for (SG-1)x100 and the creatinine concentration, the correlation was: r=0.666, P<0.001. Compared to the volunteers, the albumin and protein excretion in mg/24 h were more variable in the patients. The same was true if the albumin or protein concentrations were divided by the creatinine concentration or by (SG-1)x100. Protein and albumin concentrations were lower in dilute urines. Dividing the albumin or protein concentrations by the creatinine concentration reduced the number of false negative protein and albumin results. Dividing the albumin or protein values in mg/24 h by (SG-1)x100 eliminated fewer false negatives. Albumin concentrations increased significantly after vigorous exercise. The increase was almost eliminated when the albumin result was divided by the creatinine concentration suggesting that a decreased urine flow and not increased glomerular permeability causes an increase of post-exercise albuminuria. The same was true for proteinuria. A dipstick test plus an optical strip reader that can measure urine protein, albumin, and creatinine and calculate the appropriate ratios provides a better screening test for albuminuria or proteinuria than one measuring only albumin or protein.

Adult↗
PubMed1976

[The specific gravity of the excitation formation and conduction system of the heart compared to the working myocardium as an indication of differences in structure and composition (author's transl)].

Samples of heart conducting system tissue and samples of ordinary heart muscle (left heart, right heart, and septum interventriculare) were taken from the hearts of 50 prime-conditioned bulls. The specific gravity of the heart conducting system was significantly higher than that of ordinary heart muscle. This is surprising because it cannot be explained by a difference in water content. The question arises whether or not there are differences in the composition of protein and in the content of glycogen.

Animals↗
PubMed1991

Positional nystagmus due to alteration of the specific gravity in the labyrinth.

Horizontal positional nystagmus having characteristics similar to ice water caloric nystagmus was induced by injecting heavy water into the rabbit middle ear cavity or facial nerve through the stylomastoid foramen. Furthermore, with general administration of glycerol to normal subjects, horizontal positional nystagmus as with general administration of heavy water to experimental animals was observed. It is possible that alteration of the specific gravity arising from infiltration of heavy water or glycerol into the labyrinth accounts for the manifestation of positional nystagmus. These studies on positional nystagmus may be one of the means to elucidate the mechanism of caloric nystagmus and to examine the function of the human blood-labyrinth-barrier.

Adolescent↗
PubMed2005

A dipstick protein and specific gravity algorithm accurately predicts pathological proteinuria.

BACKGROUND: The proper strategy to screen for early chronic kidney disease is debatable, but protein-creatinine ratio from a random urine sample (UPC) commonly is used. The purpose is to determine whether dipstick data effectively identify patients with increased UPC ratios. Because urine concentration affects proteinuria interpretation, we hypothesized that dipstick protein (DSP) and specific gravity (SG) are sufficient for screening. METHODS: A hospital laboratory database was searched for urine samples simultaneously assayed for UPC ratio, DSP, and SG (n = 2,098). A random 70% of the cohort was used to generate a development model, which was validated in the remaining 30%. Samples were stratified according to DSP and SG values. A DSP versus SG matrix was created, and each sample was allocated to a discrete DSP-SG category. Proportions of samples with overt (UPC ratio > or = 500 mg/g) and nephrotic-range proteinuria (UPC ratio > or = 3,000 mg/g) were calculated for all 40 cells. RESULTS: Optimum correlations between DSP-SG cells and UPC ratios were determined for the development model, yielding 97.0% negative predictive value (NPV) for a UPC ratio of 500 mg/g or less and 97.5% positive predictive value (PPV) for a UPC ratio of 500 mg/g or greater. NPV for a UPC ratio of 3,000 mg/g or less was 99.7%. Application of the model to the validation sample showed a 96.5% NPV for a UPC ratio of 500 mg/g or less, 99.4% PPV for a UPC ratio of 500 mg/g or greater, and 99.0% NPV for a UPC ratio of 3,000 mg/g or less. CONCLUSION: DSP and SG values effectively identify patients requiring proteinuria quantification by means of UPC ratio. A Web-based tool was developed that allows DSP and SG value entry and provides a recommendation regarding the need for proteinuria quantification.

Biomarkers↗
PubMed2006

Consistently high urine specific gravity in adolescent American football players and the impact of an acute drinking strategy.

The purpose of this study was to determine whether high-school football players showed risks of fluid deficits during two-a-day training (Part 1), and whether implementing a drinking strategy could acutely improve the markers of hydration (Part 2). In Part 1, pre-training urine specific gravity (USG) and pre- and post-training body weight were measured at the morning session for 5 consecutive days of two-a-day practices to monitor the hydration status of 13 varsity players. The mean pre-training body weight was consistently lower (mean decrease of 0.5 kg, p<0.05) following the first day of measurement. Pre-training USG values remained consistently high each day (range for daily means: 1.022+/-0.003 to 1.024+/-0.005). Part 2 consisted of assessing hydration status in 46 varsity and junior varsity players prior to morning training during two-a-day training before and following implementing a drinking strategy. In association with the strategy, mean body weight increased 0.5 kg (p<0.01) and mean USG decreased from 1.021 to 1.016 (p<0.01) following the drinking protocol. The slight decline in body weight and consistently high USG (Part 1) suggested that standard fluid replacement strategies were less than optimal for a majority of the players. Implementing a drinking strategy appeared to improve hydration status based on changes in body weight and USG (Part 2).

Adolescent↗
PubMed2006

Using urine specific gravity to evaluate the hydration status of workers working in an ultra-low humidity environment.

In environments with ultra-low humidity, workers may have excessive body water loss due to evaporation through the skin, which can lead to dehydration. Before the development of clinical symptoms and signs, concentrated urine may be applied as an early indicator of dehydration. We used urine specific gravity (USG) as a biomarker to evaluate the hydration status of workers working in such an environment. We collected the urine samples from workers at a lithium battery plant during their annual health examination, and the relative humidity of some working areas called "dry rooms" in the plant was 1.5 +/- 1%. We recruited workers in those dry rooms as the exposure group (N=50) and defined the remaining workers, including administration office workers, as the comparison group (N=122). The prevalence of abnormally concentrated urine (USG>1.030) and related factors were compared between these two groups. While the exposure group were younger and had shorter employment durations compared to the comparison group (p<0.05), they had a higher prevalence of abnormally concentrated urine (p<0.01). After adjusting for age, gender, employment duration, and body surface area, we found that working in the dry rooms was associated with an odds ratio of 11.9 (95% confidence interval: 2.5 to 56.9) of having abnormally concentrated urine. Therefore, USG is a good biomarker for evaluating the hydration status of workers working in ultra-low humidity environments, who need proper protection and adequate fluid supply to prevent excess water loss and its adverse health effects.

Adult↗
PubMed1987

Formulas for fetal weight estimation by ultrasound measurements based on neonatal specific gravities and volumes.

To improve the accuracy of fetal weight estimation by ultrasound measurement, especially in low birth weight infants, including those with intrauterine growth retardation, two new formulas were developed from a new point of view. The formulas were established by (1) actual measurements of the volumes of the neonatal head and trunk with limbs, (2) analysis of the relationship between the sizes of the parts of the fetal body measured by ultrasound examination before birth and the volumes of the parts of the neonatal body, and (3) calculation of the specific gravities of the parts of the neonatal body. The prospective study showed a high correlation between estimated weights and actual birth weights with a small range of error in infants weighing between 450 and 4800 gm.

Birth Weight↗
PubMed1990

Low specific gravity urine with crystalluria as discriminant index for nephrolithiasis.

A community-based study for crystalluria in morning urine (MU) specimens was carried out under light microscopy. The MU specimens were collected from 29 males with renal stones (GI), 36 age-and sex-matched normal controls (GII) and 27 household members of GI who did not have stones (GIII). The findings can be summarized as follows. 1. In the groups as a whole, almost all crystal and crystal aggregate found was oxalate type and with highest prevalence in GI. 2. In urine with low specific gravity (SG) i.e. less than or equal to 0.010, prevalence of oxalate crystals in GI (57.7%) was significantly higher (p less than 0.05) than in both GII (5.9%) and GIII (13%). Furthermore, at this range of SG, 15 per cent of the MU specimens in GI showed aggregation of oxalate crystals, whereas, the condition was neither found in GII nor GIII. 3. Our data suggest urine supersaturation with respect to calcium oxalate was found in both renal stone patients and normal subjects but more frequently in the former and also suggests more deficiency or lack of inhibitors for oxalate crystal nucleation and aggregation in urine of renal stone patients. The occurrence of oxalate crystals and crystal aggregates in urine of low SG may be useful as an index to discriminate stone patients from normal subjects or as an index to indicate the high risk group in the community.

Adult↗
PubMed2004

The effect of specific gravity of perfluorocarbon liquid on the retina after experimental vitreous substitution.

PURPOSE: To evaluate the histological changes in the retina after experimental vitreous substitution with various amounts of perfluorophenanthrene (PFPH). METHODS: Thirty-two rabbit eyes were mechanically vitrectomized and filled up with 0.8 cc or 0.2 cc highly purified PFPH. The substance remained for 1 week (4 eyes), 2 weeks (8 eyes), 4 weeks (10 eyes) or 8 weeks (10 eyes). Eight eyes underwent the same surgical procedure without PFPH exchange to serve as a control group. A histological comparison of corresponding areas in the center and in the periphery of the inferior retina ensued. RESULTS: After 2 weeks, nuclear drop-downs and irregularities of the outer plexiform layer and of both nuclear layers were observed centrally in the eyes with a 0.8 cc substitution. The changes proceeded to irregularities and cell loss of all retinal layers with focal areas of complete destruction of the retinal architecture after 8 weeks. In contrast, single nuclear drop-downs, wrinkling of the outer nuclear layer and cell loss in the photoreceptor layer were observed in the peripheral retina at the end of the observation period. In those eyes where 0.2 cc PFPH was exchanged nuclear drop-downs were found after 2 weeks, leading to focal thinning of the outer plexiform layer and irregularities of the outer nuclear layer after 4 weeks with an insignificant increase after 8 weeks. At this time these histological alterations were comparable with those that we observed after 2 weeks in the eyes with a 0.8 cc tamponade in a corresponding area. CONCLUSIONS: Even high purification of PFPH does not prevent retinal damage. The different results in different areas after vitreous substitution with 0.2 cc and with 0.8 cc demonstrate that the high specific gravity of the substance may also play a role in the development of histological changes after extended tamponade.

Animals↗