Is specific gravity a good estimate of urine osmolality?

Imran, Sethi; Goldwater, Eva; Christopher, S Hayward; Flynn, Ethan A.; Henner, David

doi:10.1002/jcla.20424

Cited by 42 publications

(35 citation statements)

References 10 publications

(12 reference statements)

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“…Cell hydration pathways conceivably mediate the extra weight loss because the effect is associated with intake of drinking water in excess of 1L/d [26] and/or significant urine dilution [27] (specific gravity <1.01, i.e. urine osmolality<300mmol/kg [28]). Urine dilution is a sensitive indicator of hypo-osmotic cell swelling [21, 29] (see Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Qualitative and/or Quantitative Drinking Water Recommendations for Pediatric Obesity Treatment

Stookey¹

2014

J Obes Weight Loss Ther

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Objective The qualitative recommendation to ‘drink water instead of caloric beverages’ may facilitate pediatric obesity treatment by lowering total energy intake. The quantitative recommendation to ‘drink enough water to dilute urine’ might further facilitate weight loss by increasing fat oxidation via cell hydration-mediated changes in insulin. Methods This 8 week randomized intervention tested whether both qualitative-plus-quantitative (QQ) drinking water recommendations result in more weight loss than the qualitative recommendation alone (Q) in 25 children (9–12y) with body mass index at or above the 85th Percentile, given a reduced glycemic diet and usual physical activity. Random urine osmolality, saliva insulin, and body weight were assessed weekly. Mixed models explored if insulin mediated an effect of urine osmolality on weight loss. Results In intention-to-treat analyses, QQ and Q participants did not differ significantly with respect to level of urine osmolality, saliva insulin, or weight loss. Only 4 out of 16 QQ participants complied with instruction to drink enough water to dilute urine, however. In completers analyses, the compliant QQ participants, who diluted urine osmolality from 910 ± 161 mmol/kg at baseline to below 500 mmol/kg over time (8 week mean±SE: 450 ± 67 mmol/kg), had significantly lower saliva insulin over time (8 week mean±SE: 13 ± 8 pmol/l vs. 22 ± 4 pmol/l) and greater weight loss (mean ± SE: −3.3 ± 0.7kg vs. −2.0 ± 0.5 kg) than compliant Q participants (7 out of 9 participants) who maintained elevated urine osmolality over time (8- week mean±SE: 888 ± 41 mmol/kg). Urine osmolality below 500 mmol/kg was significantly associated with weight loss. Change in saliva insulin partially explained the association. Conclusions QQ recommendations may increase weight loss for those able to dilute urine. Work is warranted to pursue cell hydration effects of drinking water for pediatric obesity treatment.

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Section: Introductionmentioning

confidence: 99%

Qualitative and/or Quantitative Drinking Water Recommendations for Pediatric Obesity Treatment

Stookey¹

2014

J Obes Weight Loss Ther

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“…The urine specific gravity (USG) can also be used at the bedside to guide diabetes insipidus management if there is a delay in obtaining urine osmolality results from the laboratory. USG determined by both reagent strip and refractometry has a correlation of approximately 0.75 with urine osmolality [29]. This relationship between the specific gravity and osmolality is disturbed when the urine contains an abnormal solute, such as glucose or protein.…”

Section: Postoperative Overviewmentioning

confidence: 99%

Management of Electrolyte and Fluid Disorders after Brain Surgery for Pituitary/Suprasellar Tumours

Albanese

2015

Horm Res Paediatr

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Disturbances in salt and water balances are relatively common in children after brain surgeries for suprasellar and pituitary tumours, presenting diagnostic and therapeutic challenges. Although hypernatraemia associated with central diabetes insipidus is commonly encountered, it is hyponatraemia (HN) that poses more of a diagnostic dilemma. The main differential diagnoses causing HN are the syndrome of inappropriate antidiuretic hormone secretion, marked by inappropriate retention of water, and cerebral salt wasting, characterized by polyuria and natriuresis. Diagnosis and management can be even more difficult when these conditions precede or coexist with each other. These diagnostic and therapeutic dilemmas are discussed in detail in this review.

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“…Finally, urine dilution could disturb the assay . With regard to dilution however, only four samples with a non‐detectable result (24% of all non‐detectable samples) were strongly diluted, having an osmolality of <180 mOsm/kg (approximately corresponding to a specific gravity of <1.004, the applied cut‐off for not accepting a sample in anti‐doping procedures). In contrast, 30 samples (10%) with similarly low osmolality had positive or negative assay results.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity and specificity of detection methods for erythropoietin doping in cyclists

Heuberger

Eenoo²,

Rotmans

et al. 2019

Drug Testing and Analysis

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Recombinant human erythropoietin (rHuEPO) is used as doping a substance. Anti‐doping efforts include urine and blood testing and monitoring the athlete biological passport (ABP). As data on the performance of these methods are incomplete, this study aimed to evaluate the performance of two common urine assays and the ABP. In a randomized, double‐blinded, placebo‐controlled trial, 48 trained cyclists received a mean dose of 6000 IU rHuEPO (epoetin β) or placebo by weekly injection for eight weeks. Seven timed urine and blood samples were collected per subject. Urine samples were analyzed by sarcosyl‐PAGE and isoelectric focusing methods in the accredited DoCoLab in Ghent. A selection of samples, including any with false presumptive findings, underwent a second sarcosyl‐PAGE confirmation analysis. Hematological parameters were used to construct a module similar to the ABP and analyzed by two evaluators from an Athlete Passport Management Unit. Sensitivity of the sarcosyl‐PAGE and isoelectric focusing assays for the detection of erythropoietin abuse were 63.8% and 58.6%, respectively, with a false presumptive finding rate of 4.3% and 6%. None of the false presumptive findings tested positive in the confirmation analysis. Sensitivity was highest between 2 and 6 days after dosing, and dropped rapidly outside this window. Sensitivity of the ABP was 91.3%. Specificity of the urine assays was high; however, the detection window of rHuEPO was narrow, leading to questionable sensitivity. The ABP, integrating longitudinal data, is more sensitive, but there are still subjects that evade detection. Combining these methods might improve performance, but will not resolve all observed shortcomings.

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Is specific gravity a good estimate of urine osmolality?

Abstract: In pathological urines, direct measurement of urine osmolality should be used.

Cited by 42 publications

References 10 publications

Qualitative and/or Quantitative Drinking Water Recommendations for Pediatric Obesity Treatment

Qualitative and/or Quantitative Drinking Water Recommendations for Pediatric Obesity Treatment

Management of Electrolyte and Fluid Disorders after Brain Surgery for Pituitary/Suprasellar Tumours

Sensitivity and specificity of detection methods for erythropoietin doping in cyclists

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