- Azotemia is an elevation of blood urea nitrogen (BUN) and serum creatinine.
- Urinary specific gravity (SG) is a measure of the concentration of solutes in the urine. It measures the ratio of urine density compared with water density and provides information on the kidney’s ability to concentrate urine. A urinary specific gravity measurement is a routine part of urinalysis. [1, 2, 3] The reference range is 1.005-1.030.
- SG of urine= urine density/water density
- Water density= 1 g/cm³
- ρ = m / v (g/cm³)
- Bilirubinuria: High conjugated bilirubin in the urine
- Cholestasis (intrahepatic or extrahepatic): High GGT and Direct Bilirubin will be 50% more than of the total bilirubin.
- Low specific gravity (SG) (1.001-1.003) may indicate the presence of diabetes insipidus, a disease caused by impaired functioning of antidiuretic hormone (ADH). Low SG also may occur in patients with glomerulonephritis, pyelonephritis, and other renal abnormalities. In these cases the kidney has lost its ability to concentrate due to tubular damage.
- **High SG **may occur in patients with adrenal insufficiency,dehydration, hepatic disease, congestive heart failure, or in patients experiencing excessive water loss due to sweating, fever, vomiting, or diarrhea.
- The degree of proteinuria yields useful information on the source of protein loss; namely losses of large amounts of protein (with high urine protein to creatinine ratios) is due to glomerular, and not tubular, disease.
- Protein: Creatinine Ration:
- Persistent proteinuria with an inactive urine sediment is likely marker of chronic kidney disease (CKD) in dogs and cats.1 Recent evidence also suggests an association between renal proteinuria and progression of CKD in both species: the greater the magnitude of proteinuria, the greater the risk of renal disease progression and mortality.2-5 Importantly, treatments that have attenuated proteinuria in dogs and cats with CKD have also been associated with slowed kidney disease progression and/or improved survival.4-8 For these reasons, screening for renal proteinuria and longitudinal assessment of renal proteinuria have recently received renewed interest.
- Proteinuria is a general term that describes the presence of any type of protein in the urine, such as albumin, globulins, and Bence Jones proteins. Proteinuria of renal origin results from two major mechanisms: the first is a loss of selective glomerular filtration resulting in an increased amount of plasma protein in the filtrate; the second is an impaired resorption of the filtered protein. Albumin is the predominate protein in urine in dogs and cats in both health and renal disease.
Urine serum chemistry profile
- Although increases in BUN and creatinine are supportive of renal dysfunction, these tests are influenced by nonrenal factors as well. For example, dehydration can cause increases in BUN and serum creatinine not associated with renal failure. BUN can also be influenced by diet and GI bleeding and is considered inferior to creatinine to evaluate GFR. Serum creatinine levels can be falsely decreased in animals with severe muscle wasting and falsely increased in patients with severe muscle damage.
- Although BUN and serum creatinine increase as GFR decreases, this relationship is not linear. Large changes in GFR early in renal disease cause only small increases in BUN and serum creatinine, whereas small changes in GFR in advanced renal disease may be associated with large changes in BUN and serum creatinine.
- SG of urine= urine density/water density
- Water density= 1 g/cm³
- ρ = m / v (g/cm³)
- Protein: Creatinine Ration: