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  2. 2. OVERVIEW1. Urinalysis2. Serum/plasma urea & creatinine concentrations3. Urine protein to creatinine ratio (UPC ratio) 2
  3. 3. 1.URINALYSISMAIN INDICATIONS ARE: • Evaluation of renal & lower urinary tract abnormalities • Assessment of some metabolic/endocrine disorders • Assessment of state of hydration 3
  4. 4. Gross evaluation Specific gravity (SG)Urinalysis Biochemical analysis Sediment examination (microscopy) Culture 4
  5. 5. GROSS EVALUATION: COLOURUrine from healthy animals can vary in colour Red discolourationbut is usually light, mild or dark yellow Red discolouration may indicate haemoglobinuria, myoglobinuria or haematuria. 5
  6. 6. GROSS EVALUATION: TURBIDITY turbidity in urine fromUpper sample :Clear urine Turbid urine a cow withLower sample:Turbid (healthy horse) pyelonephritis 6
  7. 7. TURBIDITY Healthy horses and rabbits may have turbid urine due to high concentration of mucin and crystals. In other species turbidity can indicate the presence of sediment. On refrigeration, urine samples may become turbid from crystallisation of minerals which were in solution, and they may clear when returned to room temperature 7
  8. 8. Gross evaluation Specific gravity (SG)Urinalysis Biochemical analysis Sediment examination (microscopy) Culture 8
  9. 9. SPECIFIC GRAVITY (SG)Ratio of weight (density) of urine to that of an equal volume of waterat the same temperature. No units. Values depend on: - hydration status and water intake - the kidney’s concentrating ability It is a test of renal tubular function Hydration status can be determined by assessing skin turgor or by measurement of serum albumin, or PCV and total proteins. 9
  10. 10. SPECIFIC GRAVITY (SG): MEASUREMENT– Reagent test strips are unreliable for animals/Always use the refractometer– If the urine is turbid, centrifuge it before measuring SG of the supernatant 1.050 1.040 1.030 1.020 1.010 1.000 10
  11. 11. SG: INTERPRETATIONHYPERSTHENURIA: concentrated urine - >1.012 -urine of healthy, normally hydrated animalsISOSTHENURIA: urine neither concentrated nor diluted -1.007-1.012 (urine SG = plasma filtrate SG) -persistent isosthenuria warrants further investigationHYPOSTHENURIA: urine is more diluted than plasma - <1.007- persistent hyposthenuria warrants further investigation 11
  12. 12. SG: INTERPRETATION * The range of values for SG can vary according to water intake and hydration status. Usually SG in normal concentrated urine is >1.030 * WATER DEPRIVATION TEST * Contra-indication: It should never be carried out in depressed, dehydrated or azotemic animals, or if renal failure is suspected. * Indication: Confirmation of the animals ability to concentrate its urine when water is withheld. * Protocol: The urine SG is monitored every 2 hours until 5% of body weight is lost, or the urine SG is >1.020. * Interpretation: * If the urine SG increases to 1.020, tubular function and ADH availability are confirmed. * If the urine SG remains <1.020, diabetes insipidus is suspected. 12
  13. 13. Gross evaluation Specific gravity (SG)Urinalysis Biochemical analysis Sediment examination (microscopy) Culture 13
  14. 14. BIOCHEMICAL ANALYSIS URINE STRIPS Always follow manufacturer instructions 14
  16. 16. GLUCOSE- Glucose is not normally found in urine of healthy animals- Causes of glycosuria • Persistent hyperglycaemia - Diabetes mellitus • Transient hyperglycaemia - Stress in cats - Drugs (xylazine, ketamine) - IV fluids containing glucose - Convulsions • Renal tubular disorders - Fanconi syndrome - Primary glucosuria 16
  17. 17. BILIRUBIN– Not accurate for dogs/cats • Tests utilising a tablet (ictotest) can be more accurate than strip- tests • Light can break down bilirubin– Trace to + normal in healthy dogs.No bilirubin present in the urine of other healthy animals– The bilirubin in the urine is water-soluble conjugated bilirubin– Causes of bilirubinuria • Same as causes of bilirubinaemia 17
  18. 18. KETONES – Accurate test for animals • Does not detect β-hydroxybutyric acid – Ketones are not present in the urine of clinically healthy animals • Trace can be normal in rabbits – Causes of ketonuria • Diabetes mellitus, pregnancy, starvation, ketosis, immediately after calving in high–producing dairy cowsN.B. Many disorders causing anorexia in cattle (e.g. mastitis, metritis, pneumonia)will cause ketonaemia and ketonuria, but levels of ketones are generally not as highas in primary ketosis. 18
  19. 19. BLOOD / HAEMOGLOBIN- Accurate test for animals- Detects intact RBCs, haemoglobin or myoglobin- Follow-up positive result with sediment examination- Interpret positive result in conjunction with the method of urine collection (cystocentesis can be a cause of presence of blood in urine) 19
  20. 20. pH– Acceptable test for animals- Carnivores: • acidic urine is normal if fed a meat diet • alkaline urine usually reflects urinary tract infection- Herbivores: • alkaline urine is normal • acidic urine may reflect increased protein catabolism e.g. high protein diet, starvation, fever, nursing animals– Some drugs can influence pH– Not an accurate indicator of systemic acid/base balance 20
  21. 21. PROTEIN– Acceptable test for animals but can give false positive reaction in alkaline samples.– Test detects mainly albumin. Does not detect globulins– Always interpret in conjunction with SG and sediment examination (it is not abnormal to have trace protein in concentrated urine but always abnormal finding in diluted urine).– Common causes of proteinuria: • urogenital haemorrhage • urogenital inflammation • renal protein loss 21
  22. 22. NITRITE, UROBILINOGEN, LEUKOCYTES- Nitrite • Positive results may indicate bacterial infection • false negative results occur commonly- Urobilinogen • Questionable clinical usefulness- Leukocytes • False negative results common in dogs • False positive results common in cats NONE ARE RELIABLE IN EXAMINING ANIMAL URINE 22
  23. 23. 2. Serum urea & creatinine concentrations 23
  24. 24. UREA LIVER BLOOD Urea cycle Urea TISSUES Urea NH4+ 75% proteins NH4+ KIDNEYS 25% Urea UreaDietary Proteins bacteria NH4+ Urea in GASTROINTESTINAL TRACT urine 24
  25. 25. UREA and creatinine– Glomeruli: 75% of urea is excreted (excretion ↑ or ↓ when glomerular filtration rate ↑ or ↓ )– Tubules: Urea is reabsorbed (reabsorption ↑ or ↓ when glomerular filtration rate ↓ or ↑)– Creatinine is derived from creatine-phosphate, creatinine is excreted via the glomeruli. It is not reabsorbed in the tubules so excretion of creatinine is a measure of glomerular filtration rate. 25
  26. 26. BUN vs. UREA– BUN = blood urea nitrogen= concentration of the nitrogen component of urea in blood– BUN value is Lower than urea value. BUN:Urea ratio is approximately 1:2– But the term BUN is used interchangeably with urea 26
  27. 27. CREATININE KIDNEYS creatine creatinine creatinineMUSCLE creatinine BLOOD Creatinine in urine creatinine NH4+ INTESTINES 27
  28. 28. AZOTAEMIA- Increased serum/plasma urea & creatinine concentrations URAEMIA– Marked azotaemia and clinical signs (vomiting, anorexia, gastrointestinal ulceration) 28
  30. 30. PRE-RENAL AZOTAEMIA- DECREASED RENAL PERFUSION - Hypovolaemia, dehydration, cardiovascular disease  Urea is ↑ and creatinine Normal / ↑  Urine specific gravity is ↑- INCREASED UREA PRODUCTION - G.I. TRACT HAEMORRHAGE  Urea is ↑ and creatinine is Normal - HIGH PROTEIN DIET  Urea is ↑ and creatinine is Normal 30
  31. 31. RENAL AZOTAEMIA- RENAL DISEASE - ONLY evident when more than 60-75% of nephrons are compromised • Urea and creatinine are ↑ • Urine is inadequately concentrated 31
  32. 32. POST-RENAL AZOTAEMIA- URINARY TRACT OBSTRUCTION • ureter, urethra- URINARY TRACT RUPTURE • ureter, bladder, urethra - Urea and creatinine are ↑ 32
  33. 33. LOW SERUM/PLASMA UREA: CAUSES– Decreased Liver Function– Portosystemic shunt– Increased Excretion • Extreme PU/PD • Overhydration– Low protein intakeYoung Animals have a lower reference range 33
  34. 34. RUMINANTS / HORSES- Excrete most of urea via the gut (very little via kidneys). So blood urea can be normal despite severe renal disease.- Therefore blood creatinine is a more sensitive indicator of renal disease 34
  35. 35. 3.Urine protein to urinecreatinine ratio (UPC ratio) 35
  36. 36. UPC RATIO– Used to assess the clinical significance of proteinuria– Total protein & creatinine concentrations are measured in a single urine sample and expressed in the same units UPC RATIO INTERPRETATION < 1.0 Proteinuria if present is not significant MILD/MODERATE Significant proteinuria from: INCREASES (1-2) urogenital haemorrhage urogenital inflammation glomerular protein loss MODERATE/SEVERE Usually glomerular protein loss INCREASES (>2) 36
  37. 37. Urine Sediment Examination Produced by centrifugation of urine onto a slide Looking for:  Abnormal crystals  Cells  Infectious agents  Casts  Contaminants 37
  38. 38. Ammonium biurate: suggestive of liver dysfunction and/or portosystemic shunting 38
  39. 39. Conjugated bilirubin: normal in dogs, but abnormal in other species. Suggestsconjugated bilirubinemia 39
  40. 40. Calcium oxalate: suggestive of hypercalciuria, hyperoxaluria (dietary, ethyleneglycol) or calcium oxalate urolithsCan occur normally if urine has been stored 40
  41. 41. Magnesium ammonium phosphate (struvite) – present in normal animals butexcessive amounts can be an indicator of struvite uroliths or mixed urolithsCommon in bacterial-induced alkalinuria 41
  42. 42. Calcium oxalate monohydrate – suggestive of hypercalciuria or EG toxicity 42
  43. 43. Cysteine – indicative of disruption of cysteine metabolism/catabolism (drug inducedor inborn error in metabolism 43
  44. 44. Drug-associated - sulfonamides 44
  45. 45. Tyrosine – associated with severe liver disease 45
  46. 46. Tyrosine – associated with severe liver disease 46
  47. 47. RBCs – up to 5 RBC per high power field is normal. Increased RBCs in urinegenerally indicates hemorrhage into the bladder or urethra (artifact with cathetercollection in some cases) 47
  48. 48. WBCs – up to 5 WBC per high power field is normal, higher levels suggest infectionsomewhere within the urinary tract 48
  49. 49. Transitional epithelial cells from renal pelvis, ureters, urinary bladder or urethraMorphology used for detection of neoplastic change (cytology) 49
  50. 50. Squamous epithelial cells – indicator of contamination from skin, prepuce etc 50
  51. 51. Neoplastic cells – commonly transitional cell carcinomas 51
  52. 52. Bacteria – bacili on the right, cocci on the left. Presence is always abnormal – eitherinfection or contamination (storage, collection) 52
  53. 53. Fungi – presence is always abnormal – Candidiasis or Aspergillus sp. In the case ofinfection. Be aware: contamination, storage, growth on microscope slides or in stainpreparations 53
  54. 54. Parasites 54
  55. 55. Casts:Hyaline casts = precipitated proteinCellular casts: These have distinct cells withinthe protein matrix - if the cells are of epithelialorigin (i.e., not WBCs or RBCs), they are calledepithelial casts..Granular casts: As cells within the protein castmatrix break down, the cast becomes coarselythen finely granular.Waxy casts: Waxy casts are the final stage ofcast degeneration (usually originating fromcellular and granular casts). Compared tohyaline casts, they are readily observablebecause they have a smooth appearance, nointernal texture, and are more refractile than thesurrounding urine. 55
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  58. 58. Questions? 58