# Interpreting Urine Chemistry in the Context of Systemic Disease ## Quick Answer - Urinalysis connects kidney, liver, endocrine, and hematologic findings to systemic disease when interpreted alongside blood work and physical examination. - A complete urinalysis includes physical properties, chemical dipstick analysis, and sediment microscopy, with each component contributing distinct diagnostic information. - Urine chemistry alone cannot confirm a systemic diagnosis, and results must be interpreted with the full clinical picture and confirmed by a veterinarian. ## The Role of Urinalysis in Systemic Disease Detection Urinalysis is a foundational diagnostic tool in veterinary medicine because urine collects and concentrates metabolic byproducts, proteins, and cellular material from throughout the body. When a systemic disease alters blood chemistry, kidney function, or cellular turnover, those changes often appear in urine before they become clinically obvious. For a veterinarian, the urine sample is not an isolated test but a window into multiple organ systems that can be evaluated alongside blood work and physical examination findings. The diagnostic value of urinalysis depends on how it is performed and interpreted. A complete urinalysis includes three components: physical assessment of color and turbidity, chemical dipstick analysis, and microscopic sediment examination. Each component provides different information. Physical properties can suggest hemolysis, jaundice, or dehydration. Chemical analysis measures pH, protein, glucose, ketones, bilirubin, and blood. Microscopy identifies cells, casts, crystals, and microorganisms that are not visible on dipstick testing. Systemic diseases that commonly produce urine chemistry changes include diabetes mellitus, liver disease, hemolytic disorders, and kidney disease. In diabetes mellitus, hyperglycemia exceeds the renal threshold and glucose spills into urine. In liver disease, bilirubin metabolism is altered and bilirubin appears in urine. In hemolytic anemia, hemoglobin and bilirubin are released in excess and appear in urine. Each of these findings requires integration with blood tests and clinical signs to reach a diagnosis. The American Veterinary Medical Association emphasizes that pet owners should work with their veterinarian to establish preventive care plans that include routine diagnostic testing. Regular urinalysis is part of that preventive approach because it can detect early changes before clinical signs appear. The American Animal Hospital Association similarly supports life-stage based preventive care, where diagnostic testing frequency is adjusted based on the animal's age, breed, and risk factors. ## Core Principles of Urine Chemistry Interpretation ### Physical Properties and Their Systemic Significance The physical appearance of urine provides the first clues about systemic disease. Normal urine is pale yellow to amber, and the color comes from urochrome pigments. Changes in color can indicate specific conditions. Dark yellow or brown urine may suggest concentrated urine from dehydration. Red or brown urine may indicate blood, hemoglobin, or myoglobin. Orange or green urine may indicate bilirubin or bile pigments. Turbidity, or cloudiness, is another physical property. Normal urine is clear, but turbidity can result from cells, crystals, bacteria, or mucus. Turbid urine should be examined microscopically to determine the cause. The physical examination of urine is a screening step, and it does not provide a definitive diagnosis on its own. ### Chemical Dipstick Analysis The chemical dipstick is a plastic strip with pads that change color in response to specific substances in urine. The standard veterinary dipstick measures pH, protein, glucose, ketones, bilirubin, blood, and sometimes urobilinogen. Each pad has a detection limit, and results are read after a specific incubation time. The dipstick is a screening tool, and positive results must be confirmed with sediment examination or other tests. Urine pH is a measure of acidity or alkalinity. Normal urine pH in dogs and cats ranges from approximately 6.0 to 7.5, but it can vary with diet, hydration, and systemic disease. Acidic urine may be associated with metabolic acidosis, high-protein diets, or certain systemic diseases. Alkaline urine may be associated with urinary tract infections, plant-based diets, or metabolic alkalosis. The pH also influences crystal formation in the urinary tract. Protein in urine is detected by the dipstick as a color change. The dipstick is more sensitive to albumin than to globulins, and it does not detect all protein types. Proteinuria can be transient, such as after exercise or fever, or persistent, which may indicate kidney disease or systemic disease. A positive protein result should be confirmed with a quantitative test, such as a urine protein to creatinine ratio, to determine the magnitude of protein loss. Glucose in urine is not present in healthy animals because the renal tubules reabsorb filtered glucose. When blood glucose exceeds the renal threshold, glucose appears in urine. This finding is a key indicator of diabetes mellitus, but it can also occur in stress hyperglycemia or after intravenous glucose administration. The presence of glucose in urine should be confirmed with a blood glucose measurement. Ketones are metabolic byproducts of fat metabolism. They appear in urine when the body uses fat for energy instead of glucose, which occurs in diabetes mellitus, starvation, or fasting. Ketonuria is a serious finding that requires immediate veterinary attention, especially in diabetic animals. Bilirubin is a breakdown product of hemoglobin. It appears in urine when the liver cannot process bilirubin normally or when there is excessive red blood cell destruction. Bilirubinuria can indicate liver disease, bile duct obstruction, or hemolytic anemia. The dipstick is more sensitive to bilirubin in dogs than in cats. Blood in urine can be detected by the dipstick as hemoglobin or intact red blood cells. The dipstick does not distinguish between hematuria, hemoglobinuria, and myoglobinuria. Microscopy is needed to differentiate these causes. Blood in urine can indicate urinary tract infection, kidney disease, trauma, or systemic bleeding disorders. ## Urine Sediment Microscopy The urine sediment is the microscopic examination of the solid material in urine after centrifugation. It is a critical component of the complete urinalysis because it identifies cells, casts, crystals, and bacteria that are not detected by the dipstick. Red blood cells in the sediment indicate hematuria, which can originate from the kidney, ureter, bladder, or urethra. White blood cells in the sediment indicate inflammation or infection in the urinary tract. Epithelial cells can be from the renal tubules, transitional epithelium, or squamous epithelium, and their presence can indicate the site of disease. Casts are cylindrical structures formed in the renal tubules. They are composed of protein and cells, and their presence indicates renal tubular disease. Hyaline casts are protein casts that can be seen in dehydration or renal disease. Cellular casts, such as red blood cell casts or white blood cell casts, indicate active renal inflammation or hemorrhage. Crystals in the sediment are formed from minerals in the urine. The type of crystal depends on urine pH, concentration, and the presence of specific minerals. Crystals can be a normal finding, but they can also indicate a risk for urinary stones. The presence of crystals should be interpreted with the urine pH and the clinical context. Bacteria in the sediment indicate a urinary tract infection. The presence of bacteria should be confirmed with a urine culture to identify the organism and determine antibiotic sensitivity. ## Systemic Diseases That Alter Urine Chemistry ### Diabetes Mellitus Diabetes mellitus is a systemic disease characterized by hyperglycemia and glucose intolerance. The disease results from a deficiency of insulin or a resistance to insulin. In dogs and cats, diabetes mellitus is a common endocrine disorder. The Merck Veterinary Manual describes diabetes mellitus as a condition that requires lifelong management and monitoring. The urine chemistry in diabetes mellitus shows glucosuria and ketonuria. Glucosuria occurs when the blood glucose exceeds the renal threshold. Ketonuria occurs when the body uses fat for energy, which produces ketone bodies. The presence of both glucose and ketones in urine is a strong indicator of diabetes mellitus, but it must be confirmed with blood glucose measurement. The management of diabetes mellitus requires regular monitoring of blood glucose and urine glucose. The veterinarian will adjust insulin doses based on the blood glucose curve and the clinical response. Urine glucose is a less precise measure than blood glucose, but it can be used for monitoring between blood tests. ### Liver Disease Liver disease is a broad term that includes hepatitis, cirrhosis, and bile duct obstruction. The liver is the primary site of bilirubin metabolism, and liver disease can cause bilirubin to accumulate in the blood and appear in urine. The Merck Veterinary Manual describes liver disease as a condition that can be acute or chronic and that requires a combination of diagnostic tests. The urine chemistry of liver disease shows bilirubinuria. The dipstick is sensitive to bilirubin, and a positive result indicates that the liver is not processing bilirubin normally. Bilirubinuria can also occur in hemolytic anemia, where the liver is overwhelmed by the breakdown of red blood cells. The diagnosis of liver disease requires a combination of blood chemistry, bile acid testing, and imaging. Urine bilirubin is a screening test, and a positive result should be followed by a complete liver panel. ### Hemolytic Anemia Hemolytic anemia is a condition in which red blood cells are destroyed prematurely. The destruction of red blood cells releases hemoglobin, which is metabolized to bilirubin. The liver processes bilirubin, but in hemolytic anemia, the liver may be overwhelmed, and bilirubin appears in urine. The urine chemistry of hemolytic anemia shows hemoglobin and bilirubin. The dipstick may be positive for blood, and the sediment may show no red blood cells, indicating hemoglobinuria. The bilirubin may be elevated, and the urine may be dark or red. The diagnosis of hemolytic anemia requires a complete blood count, blood smear, and other tests to identify the cause of the red blood cell destruction. Urine analysis is a supportive test that can confirm the presence of hemoglobin and bilirubin. ## Integrating Urinalysis with Other Diagnostics Urinalysis is not a standalone diagnostic test. It must be interpreted with the complete blood count, serum chemistry, and physical examination. The urine chemistry provides clues, but the diagnosis requires a comprehensive evaluation. The complete blood count provides information about red blood cells, white blood cells, and platelets. In hemolytic anemia, the red blood cell count is low, and the reticulocyte count is high. In diabetes mellitus, the blood glucose is high, and the white blood cell count may be normal or elevated. The serum chemistry provides information about the liver, kidney, and metabolic function. In liver disease, the liver enzymes are elevated, and the bilirubin is high. In kidney disease, the creatinine and urea nitrogen are elevated. The physical examination provides information about the animal's overall condition. The veterinarian will assess the animal's weight, hydration, body condition, and the presence of any masses or pain. ## At a Glance | Systemic Disease | Urine Chemistry Finding | Confirmatory Test | Clinical Context | | --- | --- | --- | --- | | Diabetes mellitus | Glucosuria, ketonuria | Blood glucose, fructosamine | Polyuria, polydipsia, weight loss | | Liver disease | Bilirubinuria | Serum bile acids, liver enzymes | Icterus, vomiting, hepatomegaly | | Hemolytic anemia | Hemoglobinuria, bilirubinuria | Complete blood count, blood smear | Pale mucous membranes, tachycardia | | Kidney disease | Proteinuria, casts | Serum creatinine, urea nitrogen, urine protein to creatinine ratio | Polyuria, polydipsia, weight loss | ## Practical Workflow for Urinalysis in Systemic Disease The following workflow describes the steps a veterinarian or laboratory professional should follow when a urinalysis is performed as part of a systemic disease evaluation. ### Step 1: Collect a Quality Sample The urine sample must be collected in a clean container and processed promptly. The sample can be collected by free catch, cystocentesis, or catheterization. Cystocentesis is the preferred method for urine culture, but free catch is acceptable for routine urinalysis. The sample should be refrigerated if it cannot be processed within 30 minutes. ### Step 2: Perform the Physical Examination The physical examination includes the color, turbidity, and specific gravity. The specific gravity is a measure of the urine concentration, and it is an important indicator of kidney function. A low specific gravity indicates dilute urine, which may be seen in kidney disease or diabetes insipidus. A high specific gravity indicates concentrated urine, which may be seen in dehydration or fever. ### Step 3: Perform the Chemical Dipstick The dipstick is performed according to the manufacturer's instructions. The reagent pads are read at the specified time, and the results are recorded. The dipstick provides a semiquantitative result for each parameter. ### Step 4: Perform the Sediment Examination The sediment is prepared by centrifuging a sample of urine and examining the pellet under a microscope. The sediment is examined for cells, casts, crystals, and bacteria. The sediment examination is essential for confirming the dipstick results and for identifying the cause of the urine chemistry changes. ### Step 5: Integrate the Results The urinalysis results are integrated with the blood chemistry, complete blood count, and physical examination. The veterinarian uses the combined information to make a diagnosis and to develop a treatment plan. ## Records and Measurements The urinalysis results should be recorded in the animal's medical record. The record should include the date, the collection method, the physical properties, the chemical results, and the sediment findings. The record should also include the clinical signs and the other diagnostic tests that were performed. The specific gravity is a critical measurement that should be recorded for every urine sample. The specific gravity is measured with a refractometer, and it is a measure of the urine concentration. The normal specific gravity for dogs and cats is approximately 1.015 to 1.045, but it can vary with hydration and diet. The urine protein to creatinine ratio is a quantitative measure of proteinuria. It is a more accurate measure than the dipstick protein, and it is used to monitor kidney disease. The ratio is calculated by dividing the urine protein concentration by the urine creatinine concentration. ## Common Failure Patterns in Urinalysis Interpretation There are several common errors that can occur in urinalysis interpretation. These errors can lead to a misdiagnosis or a delay in diagnosis. ### Failure to Confirm a Positive Dipstick Result A positive dipstick result for blood, protein, or glucose should be confirmed with a more specific test. The dipstick is a screening test, and it can produce false positives. For example, the dipstick protein can be positive in alkaline urine, and the dipstick blood can be positive in the presence of myoglobin. ### Failure to Consider the Clinical Context The urinalysis results must be interpreted in the context of the clinical presentation. A positive glucose in a stressed cat may be a false positive, and a positive protein in a dog with a urinary tract infection may be a secondary finding. The veterinarian must consider the entire clinical picture. ### Failure to Perform a Sediment Examination The sediment examination is a critical part of the urinalysis. The dipstick cannot detect cells, casts, or bacteria, and the sediment is needed to confirm the dipstick results. A urine sample that is not examined under the microscope is an incomplete urinalysis. ### Failure to Confirm the Diagnosis The urinalysis is a screening test, and it is not a definitive diagnosis. A positive result should be confirmed with a more specific test. For example, a positive glucose in the urine should be confirmed with a blood glucose measurement, and a positive protein in the urine should be confirmed with a protein to creatinine ratio. ## Welfare and Safety Context The welfare of the animal is a primary consideration in veterinary medicine. The World Organisation for Animal Health emphasizes the importance of animal health and welfare in the prevention and control of disease. The urinalysis is a noninvasive diagnostic test that provides valuable information about the animal's health. The collection of a urine sample can be stressful for the animal, and the veterinarian should minimize the stress. The sample should be collected in a calm environment, and the animal should be handled gently. The veterinarian should also consider the animal's comfort and safety during the collection procedure. The urinalysis is a safe diagnostic test, but the veterinarian should be aware of the potential for complications. The cystocentesis is a needle aspiration of the bladder, and it can cause bleeding or infection. The veterinarian should use a sterile technique and should be careful to avoid the bladder. ## Professional Escalation Criteria The veterinarian should escalate the case to a specialist when the urinalysis results are abnormal and the diagnosis is not clear. The specialist may be a veterinary internal medicine specialist, a veterinary clinical pathologist, or a veterinary nephrologist. The veterinarian should also escalate the case if the animal is not responding to treatment or if the condition is worsening. The escalation should be based on the clinical presentation and the diagnostic results. ## A Decision Framework for Differentiating Hematuria, Hemoglobinuria, and Myoglobinuria The dipstick blood pad cannot distinguish between intact red blood cells, free hemoglobin, and myoglobin. This limitation creates a common diagnostic trap because each of these three findings points to a different systemic disease process. Hematuria suggests urinary tract hemorrhage, hemoglobinuria suggests intravascular hemolysis, and myoglobinuria suggests muscle injury. A veterinarian who treats all three as the same condition risks missing a hemolytic crisis or a severe myopathy. This section provides a structured decision framework that uses the physical properties of the sample, the sediment examination, and serum chemistry to separate these three causes before committing to a diagnostic plan. ### Why the Dipstick Blood Pad Cannot Stand Alone The dipstick blood pad uses a peroxidase-like reaction that detects the heme moiety. Heme is present in hemoglobin, myoglobin, and intact red blood cells. The pad does not distinguish among these sources. A strongly positive blood pad with a clear supernatant after centrifugation points toward hemoglobinuria or myoglobinuria instead of hematuria. A positive blood pad with a red sediment and a clear supernatant points toward intact red blood cells that settled during centrifugation. A red or brown supernatant with no visible red cells in the sediment points toward free hemoglobin or myoglobin in solution. The distinction matters for systemic disease interpretation. Hematuria can arise from a lower urinary tract infection, urolithiasis, neoplasia, or trauma. Hemoglobinuria arises from intravascular hemolysis, which can be caused by immune-mediated hemolytic anemia, transfusion reactions, or certain toxins. Myoglobinuria arises from muscle injury, which can be caused by trauma, exertional rhabdomyolysis, or severe metabolic derangements. Each of these conditions requires a different diagnostic workup and a different treatment plan. The Merck Veterinary Manual describes hematuria as the presence of red blood cells in urine and hemoglobinuria as the presence of free hemoglobin in urine. The manual also notes that myoglobinuria can produce a similar dipstick reaction. The clinical distinction depends on the plasma color, the urine sediment, and the serum chemistry results. ### Step 1: Assess the Plasma and Serum Color Before examining the urine sediment, the veterinarian should evaluate the plasma or serum color from a concurrently collected blood sample. This step is fast and provides a critical clue. Hemoglobinuria is almost always accompanied by pink or red plasma because free hemoglobin circulates in the blood before it is filtered by the kidney. Myoglobinuria is not accompanied by red plasma because myoglobin is cleared rapidly from the circulation and does not accumulate to visible levels. Hematuria does not change the plasma color because red blood cells are confined to the urinary tract. A practical approach is to collect a blood sample at the same time as the urine sample. Centrifuge or allow the blood to clot and inspect the supernatant. Pink or red plasma strongly supports intravascular hemolysis. Clear plasma with a red or brown urine sample supports myoglobinuria or hematuria. This single observation narrows the differential list considerably. ### Step 4: Centrifuge the Urine and Inspect the Supernatant The urine sample should be centrifuged as part of the sediment examination. After centrifugation, the veterinarian should inspect the supernatant separately from the sediment. A red supernatant with a clear sediment indicates free hemoglobin or myoglobin in the urine. A clear supernatant with a red sediment indicates intact red blood cells that settled during centrifugation. A brown or dark supernatant may indicate myoglobin, which is a smaller molecule than hemoglobin and can appear brown instead of red. The distinction between hemoglobin and myoglobin in the supernatant requires additional testing. A simple ammonium sulfate precipitation test can separate the two. Hemoglobin precipitates in an 80 percent ammonium sulfate solution, while myoglobin remains soluble. This test is not commonly performed in general practice, but it can be useful when the diagnosis is unclear. The veterinarian should consult a clinical pathologist or a reference laboratory when this distinction is needed. ### Step 5: Examine the Sediment for Red Blood Cells The sediment examination is the most direct way to confirm hematuria. The presence of intact red blood cells in the sediment confirms that the blood pad result is due to red cells. The absence of red cells in the sediment with a positive blood pad indicates hemoglobinuria or myoglobinuria. The veterinarian should count the red blood cells per high power field and record the number in the medical record. Red blood cells in the sediment can be cremated or lysed if the urine is dilute or alkaline. A dilute urine sample can cause red cells to lyse before the sediment is examined. This can produce a false negative sediment result and a false positive hemoglobinuria interpretation. The veterinarian should consider the urine specific gravity when interpreting the sediment. A low specific gravity sample with a positive blood pad and no red cells may still represent hematuria with cell lysis. ### Step 6: Measure Serum Creatine Kinase for Myoglobinuria When the urine supernatant is positive for blood but the plasma is clear and the sediment has no red cells, myoglobinuria should be considered. The serum creatine kinase concentration is the most useful confirmatory test. Creatine kinase is an enzyme released from damaged muscle cells. A markedly elevated serum creatine kinase supports muscle injury and myoglobinuria. The Merck Veterinary Manual describes creatine kinase as a sensitive indicator of muscle damage. The veterinarian should also evaluate the animal for clinical signs of muscle injury, including weakness, stiffness, muscle swelling, or a history of trauma or excessive exercise. The urine may be dark brown or red, and the animal may have a normal plasma color. The combination of a positive urine blood pad, clear plasma, no red cells in the sediment, and elevated serum creatine kinase supports a diagnosis of myoglobinuria. ### Step 7: Confirm Hemoglobinuria with a Complete Blood Count When the plasma is pink or red and the urine supernatant is red, intravascular hemolysis is the likely cause. The veterinarian should perform a complete blood count to assess the severity of the anemia. The packed cell volume and hemoglobin concentration will be low in hemolytic anemia. The blood smear should be examined for spherocytes, which are common in immune-mediated hemolytic anemia. The reticulocyte count will be elevated if the bone marrow is responding to the anemia. The veterinarian should also evaluate the serum bilirubin concentration. Hemolysis releases hemoglobin, which is metabolized to bilirubin. The bilirubin concentration will be elevated in hemolytic anemia, and the urine may also be positive for bilirubin. The combination of hemoglobinuria, bilirubinuria, anemia, and elevated serum bilirubin supports a diagnosis of hemolytic anemia. ### A Structured Decision Table for the Blood Pad The following table summarizes the decision framework for a positive urine blood pad. The veterinarian should use this table to guide the diagnostic workup and to avoid the common error of treating all positive blood pads as hematuria. | Observation | Hematuria | Hemoglobinuria | Myoglobinuria | | --- | --- | --- | --- | | Plasma color | Clear | Pink or red | Clear | | Urine supernatant | Clear | Red or brown | Red or brown | | Urine sediment | Red cells present | No red cells | No red cells | | Serum creatine kinase | Normal | Normal | Elevated | | Packed cell volume | Normal or low | Low | Normal | | Serum bilirubin | Normal | Elevated | Normal | ### Common Failure Patterns in the Blood Pad Interpretation The most common failure is to report a positive urine blood pad as hematuria without performing a sediment examination. This error can delay the diagnosis of hemolytic anemia or muscle injury. The second common failure is to interpret a positive blood pad in a dilute urine sample as hemoglobinuria when the red cells have lysed during storage. The veterinarian should always consider the urine specific gravity and the time between collection and processing. A third failure pattern is to ignore the plasma color. The plasma color is a fast and reliable indicator of intravascular hemolysis. A veterinarian who does not collect a blood sample at the same time as the urine sample loses this diagnostic information. The veterinarian should always collect a blood sample when a urine sample is collected for systemic disease evaluation. A fourth failure pattern is to treat myoglobinuria as a urinary tract problem. Myoglobinuria is a muscle problem, and the treatment is directed at the muscle injury and the underlying cause. The veterinarian should not place a urinary catheter or perform a cystocentesis in an animal with suspected myoglobinuria unless there is a separate indication for the procedure. ### Records and Measurements for the Blood Pad Workup The medical record should include the urine sample collection method, the time from collection to processing, the urine color and turbidity, the specific gravity, the dipstick blood result, the sediment red blood cell count, the plasma color, the serum creatine kinase concentration, and the packed cell volume. The record should also include the clinical signs and the physical examination findings. The veterinarian should record the urine specific gravity because it affects the interpretation of the sediment. A low specific gravity sample can cause red cell lysis, which can produce a false negative sediment result. The record should also include the serum creatine kinase concentration when myoglobinuria is suspected. The normal range for creatine kinase varies by laboratory, and the veterinarian should interpret the result with the reference interval. ### Professional Escalation Criteria for the Blood Pad Workup The veterinarian should escalate the case to a veterinary internal medicine specialist or a veterinary clinical pathologist when the urine blood pad is positive and the cause is not clear after the initial workup. The specialist can perform additional testing to distinguish hemoglobinuria from myoglobinuria, including the ammonium sulfate test or a urine protein electrophoresis. The veterinarian should also escalate the case when the animal has a severe anemia, a suspected immune-mediated hemolytic anemia, or a suspected toxin exposure. These conditions require specialized treatment and monitoring. The veterinarian should also escalate the case when the animal has a severe muscle injury and the serum creatine kinase concentration is markedly elevated. ### Welfare and Safety Context for the Blood Pad Workup The World Organisation for Animal Health emphasizes the importance of animal health and welfare in the prevention and control of disease. The blood pad workup is a noninvasive diagnostic process that provides valuable information about the animal's health. The veterinarian should minimize the stress of the blood and urine collection procedures and should handle the animal gently. The veterinarian should also consider the safety of the animal during the diagnostic workup. An animal with a severe hemolytic anemia may be unstable and may require oxygen therapy or a blood transfusion. An animal with myoglobinuria may be in pain and may require analgesia. The veterinarian should stabilize the animal before performing the diagnostic workup. ### Practical Implementation Steps for the Blood Pad Workup The following steps describe the practical implementation of the blood pad workup in a clinical setting. 1. Collect a urine sample and a blood sample at the same time. 2. Centrifuge the blood sample and inspect the plasma color. 3. Centrifuge the urine sample and inspect the supernatant and the sediment. 4. Examine the sediment for red blood cells and record the count. 5. If the plasma is pink or red, perform a complete blood count and a serum bilirubin. 6. If the plasma is clear and the sediment has no red cells, perform a serum creatine kinase. 7. Integrate the results with the physical examination and the other diagnostic tests. 8. Record all findings in the medical record. 9. Escalate the case to a specialist if the diagnosis is not clear or if the animal is unstable. ### Comparison with the Standard Urinalysis Workflow The blood pad workup is a focused extension of the standard urinalysis workflow. The standard workflow includes the physical examination, the chemical dipstick, and the sediment examination. The blood pad workup adds the plasma color assessment and the serum creatine kinase measurement to the standard workflow. These additional steps are necessary to distinguish the three causes of a positive urine blood pad. The standard workflow is sufficient for most urinalysis evaluations. The blood pad workup is indicated when the urine blood pad is positive and the cause is not clear. The veterinarian should use the blood pad workup when the urine is red or brown, when the sediment has no red cells, or when the plasma is pink or red. The blood pad workup is also indicated when the animal has clinical signs of hemolysis or muscle injury. ### Limitations of the Blood Pad Workup The blood pad workup has several limitations. The ammonium sulfate test for hemoglobin and myoglobin is not commonly performed in general practice and may require a reference laboratory. The serum creatine kinase concentration can be elevated in a variety of conditions, and it is not specific for myoglobinuria. The plasma color can be affected by lipemia or hemolysis during blood collection, which can produce a false pink color. The veterinarian should interpret the blood pad workup with the full clinical picture. The blood pad workup is a decision framework, and it does not replace the clinical judgment of the veterinarian. The veterinarian should use the blood pad workup to guide the diagnostic plan and to avoid the common error of treating a positive urine blood pad as hematuria without further investigation. ## Frequently Asked Questions ### What does a positive glucose in the urine mean? A positive glucose in the urine indicates that the blood glucose is above the renal threshold. This is a common finding in diabetes mellitus, but it can also occur in stress hyperglycemia or after intravenous glucose. The veterinarian should confirm the finding with a blood glucose measurement. ### What does a positive bilirubin in the urine mean? A positive bilirubin in the urine indicates that the liver is not processing bilirubin correctly, or that there is excess red blood cell breakdown. This can be a sign of liver disease or hemolytic anemia. The veterinarian should perform a complete liver panel and a blood count to determine the cause. ### What does a positive blood in the urine mean? A positive blood in the urine can indicate red blood cells, hemoglobin, or myoglobin. The dipstick cannot distinguish between these causes, and the sediment examination is needed to identify the cause. The blood in the urine can be from a urinary tract infection, kidney disease, or trauma. ### What does a low specific gravity mean? A low specific gravity indicates that the urine is dilute. This can be seen in kidney disease, diabetes insipidus, or excessive water intake. The veterinarian should perform a blood chemistry and a water deprivation test to determine the cause. ### What does a high specific gravity mean? A high specific gravity indicates that the urine is concentrated. This can be seen in dehydration, fever, or a high protein diet. The veterinarian should consider the hydration status and the clinical presentation. ### What does a positive ketone in the urine mean? A positive ketone in the urine indicates that the body is using fat for energy. This can be seen in diabetes mellitus, starvation, or fasting. The veterinarian should perform a blood glucose measurement and a blood ketone measurement to determine the cause. ### What does a positive glucose in the urine mean? A positive glucose in the urine indicates that the blood glucose is above the renal threshold. This is a common finding in diabetes mellitus. The veterinarian should confirm the blood glucose and evaluate the animal for other signs of diabetes. ### What does a positive protein in the urine mean? A positive protein in the urine indicates that the protein is leaking into the urine. This can be a sign of kidney disease, urinary tract infection, or systemic disease. The veterinarian should perform a protein to creatinine ratio and a urine culture to determine the cause. ## Related Veterinary Guides - [Anesthesia for Patients with Endocrine Disease: Diabetes and Hyperthyroidism](/knowledge/veterinary-medicine/anesthesia-analgesia/anesthesia-patients-endocrine-disease-diabetes-hyperthyroidism) - [Anesthesia for Patients with Liver Disease: Drug Metabolism and Dosing](/knowledge/veterinary-medicine/anesthesia-analgesia/anesthesia-patients-liver-disease-drug-metabolism-dosing) - [Laboratory Monitoring of Liver Disease: Serial Biochemistry and Prognostic Indicators](/knowledge/veterinary-medicine/clinical-pathology/laboratory-monitoring-liver-disease) - [Veterinary Urinalysis Strips at Home: Leukocytes, Protein, pH, Microalbuminuria, and Vet Confirmation](/knowledge/veterinary-medicine/at-home-diagnostics/canine-urine-test-strips-infection) - [Liver Disease Symptoms In Dogs](/knowledge/veterinary-medicine/symptom-guides/liver-disease-symptoms-in-dogs) ## References and Further Reading - [Pet Care](https://www.avma.org/resources-tools/pet-owners). American Veterinary Medical Association. - [AAHA Guidelines](https://www.aaha.org/resources). American Animal Hospital Association. - [Global Guidelines](https://wsava.org/global-guidelines). World Small Animal Veterinary Association. - [Merck Veterinary Manual](https://www.merckvetmanual.com/). Merck Veterinary Manual. - [Cornell University College of Veterinary Medicine](https://www.vet.cornell.edu/). Cornell University. - [Animal Health and Welfare](https://www.woah.org/en/what-we-do/animal-health-and-welfare). World Organisation for Animal Health. - [Urinary Tract Disorders of Foals.](https://pubmed.ncbi.nlm.nih.gov/35282963). The Veterinary clinics of North America. Equine practice, 2022. - [Systemic effects of periodontal disease in cats.](https://pubmed.ncbi.nlm.nih.gov/23193952). The veterinary quarterly, 2012. - [Diagnosis of urinary tract infections.](https://pubmed.ncbi.nlm.nih.gov/15223209). The Veterinary clinics of North America. Small animal practice, 2004. - [Alimentary lymphoma in cats and dogs.](https://pubmed.ncbi.nlm.nih.gov/21486644). The Veterinary clinics of North America. Small animal practice, 2011. - [Diagnosis and treatment of avian renal disease.](https://pubmed.ncbi.nlm.nih.gov/16407082). The veterinary clinics of North America. Exotic animal practice, 2006. > This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.