Indicated below are guidelines for interpreting the USG in animals. Measurements of GFR or serum biochemical analytes of GFR was not done in these dogs ( Rudinsky et al 2019). One study showed that the first morning urine sample of clinically healthy dogs ranged from as low as 1.010 to >1.060 in individual dogs and that the first morning urine varied by as high as 0.015 units (minimum to maximum) in different samples collected from the same dog over 2 weeks (within dog variability). At a concentration of 2400 mg/dL, the USG increased by 0.002 to 0.008 in pooled feline urine with USG 1.10) with radiographic contrast agents, such as iohexol, which are eliminated in the urine typically within 24-48 hours after contrast imaging studies ( Seshia and Dickinson 2020).įirst morning urine samples are frequently recommended when evaluating USG in dogs (it is believed that this would represent the “most naturally concentrated” urine sample. A decreasing linear relationship became evident when urine was spiked with 600 – 2400 mg/dL, but there was more individual cat variation (leading to r 2 ranging from 0.26 to 0.48 for these glucose concentrations). Feline urine: Addition of 50-300 mg/dL had random effects (increase and decrease of USG of 0.007) in individual cats with USG > 1.030.
![urine specific gravity range urine specific gravity range](https://image3.slideserve.com/5498707/specific-gravity-sg-l.jpg)
Although these changes may not increase the USG into the “appropriate range” nor substantially interfere with distinguishing between prerenal and renal azotemia with the USG, it will interfere with determination of hyposthenuric and isosthenuric USGs.
![urine specific gravity range urine specific gravity range](https://image1.slideserve.com/2773692/slide6-n.jpg)
There was a linear relationship between the difference in USG before and after spiking and the initial USG concentration (r 2 ranging from 0.78 to 0.98 for glucose concentrations between 12 g/dL). Canine urine: Addition of 300 mg/dL glucose increased the USG by 0.001-0.002 in samples with a USG 0.004 in samples with USG 1.040.Glucose: A study in which glucose was spiked into pooled canine and feline urine of different USGs showed the following:.The effect of these substances on USG does depend on the refractometer, some of which are more accurate than others ( Tvedten et al 2015).Ī concentration of 1 g/dL of the following substances in urine has been reported to increase the USG as follows:ī USG dependent Behrend et al 2019 (see below) Protein and glucose: The presence of large amounts of protein and glucose will alter the USG and should be considered when interpreting USG results.Central diabetes insipidus results from lack of ADH, the consequence of which is usually hyposthenuric urine (urine that cannot be concentrated USG 1.020) ( Cridge et al 2018), however color is not a surrogate for USG measurement.įactors affecting USG other than concentrating ability ADH also promotes urea absorption, which contributes to medullary interstitial tonicity. Antidiuretic hormone (ADH): This is produced by the hypothalamus and stored in the posterior pituitary. ADH opens water pores (aquaporins) in the distal convoluted and collecting tubules allowing for water to be absorbed passively along a concentration gradient established by a hypertonic medulla. This concentrates the urine.In order for the kidney to conserve water by concentrating urine, the kidney needs the following:
![urine specific gravity range urine specific gravity range](https://image.slidesharecdn.com/osmoregulation-gawad-dng-mansours-20-june-2014-140626123951-phpapp01/95/osmoregulation-urine-dilution-concentration-5-638.jpg)
Thus, in the setting of azotemia or an increased urea nitrogen and/or creatinine concentrations, USG is used to determine whether concentrating ability is adequate and is very useful for distinguishing between causes of azotemia. However animals that are dehydrated, hypovolemic or have decreased effective blood circulating volume should be conserving water (and trying to reconstitute effective blood volume), therefore concentrating their urine. A wide USG range is possible in healthy euhydrated animals.
![urine specific gravity range urine specific gravity range](https://i.pinimg.com/originals/a3/85/53/a38553764b80f49e7dec5c45a71bf8c5.png)
Knowledge of urinary solute concentration is essential for proper interpretation of urea and creatinine, which are indicators of glomerular filtration rate.