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It’s not just water !

It’s not just water !. An introduction to Urinalysis as performed in the Clinical Laboratory. Student Objectives:. Upon completion of this lecture presentation and the laboratory analysis, students will be expected to: 1. Describe the major functions of the kidney.

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It’s not just water !

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  1. It’s not just water ! An introduction to Urinalysis as performed in the Clinical Laboratory.

  2. Student Objectives: • Upon completion of this lecture presentation and the laboratory analysis, students will be expected to: 1. Describe the major functions of the kidney. 2. List the major structures of the kidney involved in urine formation. 3. Describe the importance of performing Urinalysis.

  3. Student Objectives - continued: 4. Observe the various urine elements detected via dipstick chemical analysis. 5. Observe the basic cell types found in the microscopic analysis of urine sediment. 6. Name the clinical laboratory professionals who perform urinalysis testing and explain the education each requires.

  4. Topics • This presentation covers the following topics: • What is Urinalysis? • Review of kidney function • Macroscopic examination of urine • Chemical examination of urine • Microscopic examination of urine • Who performs urinalysis testing? • Summary and References

  5. What is Urinalysis? • Urinalysis – or the analysis of urine – is one of the oldest laboratory procedures in the practice of medicine. • It is a good test for assessing the overall health of a patient. Courtesy of the National Library of Medicine

  6. What is Urinalysis? • It provides information about: • The state of the kidney and urinary tract. • Metabolic or systemic (non-kidney) disorders. • Urinalysis can reveal diseases that have gone unnoticed because they do not produce striking signs or symptoms. • Examples include diabetes mellitus, various forms of kidney failure, and chronic urinary tract infections.

  7. Review of Kidney Function • Urine is composed of approximately 96% water and 4% dissolved substances derived from food or waste products of metabolism. • The actual composition of urine varies, depending on diet, metabolism, general health of the body, and health of the kidney. • Urinalysis is performed to assess the urine’s composition as well as kidney function.

  8. Review of Kidney Function • Recall the urinary system consists of two kidneys, two ureters and the bladder.

  9. Review of Kidney Function • Also recall the role of blood - to bring nutrients and oxygen to cells of the body and to carry waste materials away from those cells. • The kidney has the largest role in controlling the chemical composition of the blood in order to maintain proper cell function in the body.

  10. Review of Kidney Function In the kidney, blood undergoes filtration and dialysis to separate waste compounds that will be removed from the body from those that will be returned to the circulating blood. Figure 1

  11. Review of Kidney Function • More specifically, the kidney has the functions of: • removal of waste products from the blood • retention of nutrients such as proteins and glucose • maintenance of acid-base balance • regulation of water and electrolyte (salt) content of the body • hormone synthesis

  12. Urine is formed in the kidney structure called the nephron. Each kidney contains about one million nephrons. The nephron is made up of a glomerulus and a set of tubules. Review of Kidney Function Cross section of a nephron

  13. Review of Kidney Function • The tubular portion of the nephron consists of several structures: • Proximal convoluted tubule • Loop of Henle • Distal convoluted tubule • Collecting duct

  14. Review of Kidney Function • Urine is formed through a three phase process of: • Filtration • Reabsorption • Secretion

  15. Review of Kidney Function • Filtration of the blood occurs within the specialized collection of capillaries in the glomerulus. • The glomerulus permits water and small molecules and ions from the blood to enter a surrounding tubule called the Bowman’s capsule. This is called the filtrate. • Blood cells and large protein molecules remain in the blood and return to the venous circulation.

  16. Review of Kidney Function • Reabsorption of essential chemicals the body needs (glucose, amino acids, NaCl and other salts, water and vitamins)occurs within the nephron’s proximal tubule, Loop of Henle, and distal tubule. • Reabsorption prevents the loss of necessary body compounds but also adjusts the concentration of urine so it is more dilute when the body has more water (i.e., hydrated) and more concentrated when the body is short of water (i.e., dehydrated).

  17. Review of Kidney Function • Secretionof foreign chemicals the body does not need(ammonia, drugs, hormones, toxins)begins in the proximal tubules and continues in the distal tubule and the collecting duct. • Secretion of excess ions such as H+ and K+ help establish electrolyte and acid-base balance.

  18. Review of Kidney Function • All three processes of filtration, reabsorption and secretion occur simultaneously as a result of complex cellular transport mechanisms and buffering mechanisms within the nephron tubules. • The glomerular filtrate becomes more concentrated and acidic after it leaves the distal tubule and enters the collecting duct. • The fluid that leaves the collecting duct is now urine.

  19. Review of Kidney Function • The processes of glomerular filtration and renal tubular reabsorption and secretion are can become affected when the kidney is compromised by disease. • Loss of renal function can be caused by variety of conditions such as: • congestive heart failure • injury to the glomerulus or tubules caused by drugs, heavy metals and viral infections • diabetes, hypertension and kidney stones.

  20. Urinalysis • Renal function tests, such as the urinalysis, are used to screen for the cause and the extent of renal dysfunction. • Urinalysis consists of the following measurements: • Macroscopic exam • Chemical exam • Microscopic exam of the sediment

  21. Macroscopic Exam • Examination of the physical properties including…. • Color • Clarity (or transparency)

  22. Macroscopic Exam • Color - normal • yellow (straw to amber) • Color - abnormal (due to disease, drugs or diet) • pale to colorless • amber (dark yellow) • orange • pink or red • green • brown or black

  23. Macroscopic Exam • Clarity (or transparency) - normal • clear • Clarity - abnormal (due to insoluble elements such as cells, crystals, etc.) • hazy • cloudy • turbid

  24. Macroscopic Exam Left to right: Straw, clear; yellow, clear; yellow, hazy; yellow, clear; red-orange, clear; brown, hazy.

  25. Chemical Exam • The presence of normal and abnormal chemical elements in the urine are detected using dry reagent strips. • These plastic strips contain absorbent pads with various chemical reagents for determining a specific substance.

  26. Chemical Exam • When the test strip is dipped in urine the reagents are activated and a chemical reaction occurs. • The chemical reaction results in a specific color change.

  27. Chemical Exam • After a specific amount of time has elapse, this color change is compared against a reference color chart provided by the manufacturer of the strips.

  28. Chemical Reaction Chart

  29. Chemical Exam • The intensity of the color formed is generally proportional to the amount of substance present.

  30. Typical Substances Tested & Significance • pH- partial assessment of acid base status; alkaline pH indicates old sample or urinary tract infection • Specific Gravity - state of kidney and hydration status of patient • Protein - primarily detects protein called albumin; important indicator in the detection of renal disease • Glucose - primarily detects glucose (sugar); important indicator of diabetes mellitus

  31. Typical Substances Tested & Significance • Blood - red blood cells, hemoglobin, or myoglobin (muscle hemoglobin); sensitive early indicator of renal disease • Ketone- normal product of fat metabolism; increased amounts seen in diabetes or starvation (extreme dieting) • Bilirubin- detects bilirubin (a product of red cell breakdown); indicator of liver function • Urobilinogen- another by-product of red cell breakdown; increased amounts seen in fever, dehydration, hemolytic anemia and liver disease

  32. Typical Substances Tested & Significance • Nitrite- certain bacteria convert normal urine nitrate to nitrite; indicator of urinary tract infection • Leukocyte Esterase - detects esterase enzyme present in certain white blood cells (e.g, neutrophils, monocytes); indicator of urinary tract infection

  33. Example Chemical Analysis Results ...

  34. Elevated pH (alkaline) (Normal for comparison)

  35. Positive Glucose (Normal for comparison)

  36. Positive Blood & Ketones (Normal for comparison)

  37. Positive Blood and Leukocyte Esterase (Normal for comparison)

  38. Microscopic Exam • Most commonly used procedure for the detection of renal and/or urinary tract disease. • This exam consists of reviewing the solid material suspended in the urine - both chemical and cellular.

  39. Microscopic Exam • Requires a well-trained laboratory professional who is: • skilled in the use of various microscopic techniques such as bright field and phase microscopy • able to distinguish normal or contaminating items from abnormal, pathologic elements • knowledgeable of the clinical significance of each finding and its relationship to the chemical and physical analysis

  40. Microscopic Exam • The urine specimen is centrifuged and the liquid portion is poured off. • The concentrated cellular sediment ….

  41. Microscopic Exam …. is then placed on a microscope slide, covered with a coverslip and ….

  42. Microscopic Exam • … viewed under a microscope.

  43. Microscopic Exam • A variety of normal and abnormal cellular elements may be seen in urine sediment such as: • Red blood cells • White blood cells • Mucus • Various epithelial cells • Various crystals • Bacteria

  44. Microscopic Exam • Red blood cells • presence of a few is normal • higher numbers are indicator of renal disease • result of bleeding at any point in urinary system 40x objective

  45. Microscopic Exam • White blood cells • a few are normal • high numbers indicate inflammation or infection somewhere along the urinary or genital tract 40x objective

  46. Microscopic Exam • Mucus • look like long, ribbon-like threads • common finding in urine sediment • secreted by glands in the lower urinary tract 40x objective

  47. Microscopic Exam • Epithelial cells • cells are large and flat • normal cells that line the urinary and genital tract or renal tubules 40x objective

  48. Microscopic Exam • A variety of normal and abnormal crystals may be present in the urine sediment.

  49. Microscopic Exam • Crystals of calcium oxalate • colorless octahedron • found in acid urine • Crystals of triple phosphate • colorless, “coffin-lid” prism • common finding; not clinically significant

  50. Microscopic Exam • Hyaline Casts • colorless and fatter than mucus • a few are normal • may be increased after strenuous exercise • form when protein solidifies in the nephron Hyaline cast & epithelial cell, 40x objective

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