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Emergency Medicine
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
IV fluids. Colloid may be given to maintain intravascular volume then crystalloid at 2/3 maintenance if the child is unable to feed. Beware hyponatraemia from reduced free water clearance. Orogastric feeding may be preferred in the acute phase as a nasal tube will increase airway resistance.
Therapeutic Uses and Side Effects
Published in Fazal-I-Akbar Danish, Ahmed Ehsan Rabbani, Pharmacology in 7 Days for Medical Students, 2018
Fazal-I-Akbar Danish, Ahmed Ehsan Rabbani
Renal: Loss of ability of collecting tubules to conserve water (under the influence of ADH) → excessive free water clearance → polyuria and polydypsia. This is called nephrogenic diabetes insipidus.Chronic interstitial nephritis.Minimal change glomerulonephritis (→ nephrotic syndrome).
Significance of Hormones in Regulation of Metabolism During Exercise
Published in Atko Viru, Adaptation in Sports Training, 2017
The water content of body fluid compartments depends on osmolality. To check water diuresis independent of plasma and urine osmolality, the free water clearance is calculated. During exercise the free water clearance tended to become positive in humans. This change was in combination with the increased vasopressin concentration in the plasma.254 During repeated exercises the increases in the vasopressin level and plasma osmolality were simultaneous.255 Prostaglandins may block the action of vasopressin. Nevertheless, in men an inhibition of prostaglandin synthesis was evoked by aspirin administration for 3 days prior to exercise. This procedure, however, did not influence the alterations in creatine clearance, urine volume, osmolar clearance, and electrolyte excretion.256
Adequacy of Daily Fluid Intake Volume Can Be Identified From Urinary Frequency and Perceived Thirst in Healthy Adults
Published in Journal of the American College of Nutrition, 2020
Matthew A. Tucker, Aaron R. Caldwell, Matthew S. Ganio
A number of factors influence individual variability in DFI needs including environmental conditions, physical activity levels, body morphology, and metabolism (7–9). For these reasons, blanket recommendations on a target DFI that individuals should strive to achieve come with a number of caveats. In recent years, several studies have examined links between total DFI, markers of urinary concentration, and circulating levels of arginine vasopressin (AVP) (10, 11). These studies have raised the idea that while recommendations of a DFI based on principles of urinary water and solute excretion can certainly be of value (12), determining an objective method for individuals to self-assess hydration status and adequacy of their DFI could be of tremendous potential utility. An increase in urine output (and subsequently urinary frequency [UF]) is typically indicative of greater free-water clearance, suggesting suppression of circulating AVP and thus less renal conservation of body water. This has important implications given the apparent link between low-volume, highly-concentrated urine output and chronic disease risk (13, 14), as well as AVP contributing to the progression of chronic kidney disease and decline in glomerular filtration rate (15, 16).
Spot Sample Urine Specific Gravity Does Not Accurately Represent Small Decreases in Plasma Volume in Resting Healthy Males
Published in Journal of the American College of Nutrition, 2018
Matthew A. Tucker, Cory L. Butts, Alf Z. Satterfield, Ashley Six, Evan C. Johnson, Matthew S. Ganio
All urine samples were analyzed for USG, osmolality (Uosm), and color. The postintervention sample was analyzed for USG, Uosm, and color individually before being mixed with the rest of the urine collected to form a complete 24-hour sample. Additionally, total volume was measured on the 24-hour samples. USG was determined on each sample using a calibrated handheld refractometer (Master-SUR/NM, Atago, Japan). Urine osmolality was measured in duplicate using freezing point depression osmometry (model 3250, Advanced Instruments Inc., Norwood, MA). Color was assessed in a well-lit room using the 8-level color scale where the sample was in a glass tube against a plain white background [11,27]. Samples were weighed to the nearest 5 g (i.e., 5 ml; OHAUS Catapult 1000, Pine Brook, NJ) to determine volume. Osmolar clearance (Cosm) and free water clearance (CH2O) were calculated using the following standard equations [28] where urine flow rate (V) was equal to the 24-hour urine volume converted to a milliliters per minute value:
Impact of obesity with or without hypertension on systemic haemodynamic and renal responses to lower body negative pressure
Published in Blood Pressure, 2021
Nima Vakilzadeh, Dusan Petrovic, Marc Maillard, Lucie Favre, Eric Grouzmann, Gregoire Wuerzner
During orthostatic stress, water and sodium retention occurred leading to decreases in urinary output and free water clearance and an increase in urine osmolality in all groups. However, water retention was more marked in the OBN than in the H and OBH groups (Figure 2). The increase in urine osmolality was also more pronounced in the OBN than in the H group during LBNP. Sodium excretion and lithium clearance decreased during the LBNP period in the H and the OBN group only with no difference in the magnitude of the response between groups.