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2015-10-29 17:35:27

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  1. Nitrogen containing compounds that are not proteins, amino acids or polypeptides
    Non-protein Nitrogen Compounds
  2. The determination of non-protein nitrogenous substances in the blood has traditionally been used to monitor
    renal function.
  3. Majority of these npn compounds arise from
    catabolism of proteins and nucleic acids
  4. BUN?
    Urea Nitrogen (Blood)
  5. Highest concentration of NPN in blood
    Major excretory product of protein metabolism
    These processes release nitrogen, which is converted to ammonia
    Synthesized in the liver from CO2 and Ammonia that arises from deamination of amino acids
    Urea Nitrogen (Blood) BUN
  6. the term blood urea nitrogen (BUN) has been used to refer to
    urea determination
  7. Concentration of Urea Nitrogen (Blood) BUN is determined by:
    • Renal function
    • Dietary intake
    • Protein catabolism rate
  8. hydrolysis of urea to ammonium ion , then detect ammonium ion (NH4+)
  9. The most common method couples the urease reaction with glutamate dehydrogenase
  10. measure a chromagen produced directly from urea
    Measuring urea - direct method
  11. methods measure ammonia, produced from urea
    Indirect methods
  12. Measurement of urea is used to?
    • evaluate renal function
    • to assess hydration status
    • to aid in the diagnosis of renal disease
    • and to verify adequacy of dialysis
  13. elevated conc. of urea in blood
  14. Very high plasma urea concentration accompanied by renal failure is called
    • uremia, or the
    • uremic syndrome
  15. Causes of urea plasma elevations are
    • Prerenal
    • Renal
    • postrenal
  16. Reduced renal blood flow Less blood is delivered to the kidney less urea filtered.
    High protein diet or increased catabolism (Fever, major illness, stress)
    Pre-Renal Azotemia
  17. Anything that produces a decrease in functional blood volume, include:
    • Congestive heart failure,
    • shock,
    • hemorrhage,
    • dehydration
  18. Decreased renal function causes increased blood urea due to poor excretion
    Acute & Chronic renal failure
    Glomerular nephritis
    Tubular necrosis
    other Intrinsic renal disease
    Renal Azotemia
  19. Obstruction of urine flow
    Renal calculi
    Tumors of bladder or prostate
    Severe infections
    examples of
    Post-Renal Azotemia
  20. Low protein dietary intake
    Liver disease (lack of synthesis)
    Severe vomiting and/or diarrhea (loss)
    Decreased Urea Nitrogen
  21. Formed by the muscle
    Amount proportional to muscle mass, constant excretion rate
    Freely excreted by the kidney glomerulus
    Less influenced by diet
  22. Plasma creatinine concentration is a function of:
    • relative muscle mass
    • rate of creatine turnover
    • and renal function
  23. which is very good test to evaluate renal function
  24. Measurement of creatinine concentration is used to determine sufficiency of?
    • kidney function
    • severity of kidney damage
    • monitor progression of kidney disease
  25. measure of amount of creatinine eliminated from blood by kidneys
    Creatinine clearance
  26. volume of plasma filtered by glomerulus per unit of time
    Glomerular filtration rate (GFR):
  27. Abbreviated Modification of Diet in Renal Disease (MDRD) equation: includes 4 variables what are they?
    • creatinine concentration,
    • age,
    • gender,
    • ethnicity
  28. With increasing damage to the kidney by disease, GFR ___________ before clinical symptoms
  29. Plasma concentration of creatinine is_____________  to clearance
    inversely proportional
  30. a small molecule that may serve as a better surrogate for GFR
    Cystatin C
  31. BUN/Creatinine Ratio generally between?
    10:1 and 20:1
  32. Increased BUN/Creatinine Ratio ratio indicates ?
    • catabolic states of tissue breakdown
    • compromised blood flow
  33. Decreased BUN/Creatinine Ratio ratio indicates
    • acute tubular necrosis
    • low-protein diet, starvation
    • severe liver disease
  34. Prerenal  Pathological Conditions Caused by reduce blood flow or cardiovascular failure will have BUN ____ Creatinine _____ Ratio_____
    • Increased
    • Normal
    • Increased
  35. Analytical Methods (Creatinine)
    • Jaffe reaction
    • Kinetic Jaffe method
    • Coupled enzymatic methods
    • Isotope dilution mass spectrometry
  36. May be measured in plasma, serum, or urineHemolyzed & icteric samples should be avoided.May be refrigerated for 4 days; frozen for longer storage
    Specimen Requirements & Interfering Substances for measuring creatinine
  37. Ascorbate, glucose, α-keto acids, & uric acids may increase creatinine concentration measured by Jaffe reaction
    Bilirubin causes negative bias in both Jaffe & enzymatic methods.
    Patient use of cephalosporin antibiotics, dopamine, lidocaine
    Sources of Error in createnin measurments
  38. End product of purine (nucleic acid) metabolism
    very insoluble and can form kidney stones
    Present in plasma as monosodium urate
    At plasma pH → relatively insoluble
    Uric Acid
  39. Serum uric acid depends on?
    • purine synthesis and metabolism
    • dietary intake and metabolism
    • renal function
  40. Increased uric acid seen in?
    • gout
    • increased cell turnover
    • renal impairment
  41. assess inherited disorders of purine metabolism
    to confirm diagnosis and monitor treatment of gout
    to assist in the diagnosis of renal calculi
    to prevent uric acid nephropathy during chemotherapeutic treatment,
    and to detect kidney dysfunction
    we would measure?
    Uric acid
  42. Primarily in men
    Onset 30-50 years
    UA greater than 6.0 mg/dL
    Pain & inflammation of joints by precipitation of sodium urates in tissues
    Increased risk of renal calculi
    hyperuricemia due to overproduction of uric acid in 25-30%
  43. occurs in patients on chemotherapy for diseases such as leukemia & multiple myeloma.
    Allopurinol inhibits xanthine oxidase, an enzyme in the uric acid synthesis pathway, is used to treat these patients
    Increased catabolism
  44. causes elevated levels of uric acid because filtration and secretion are hindered
    Chronic renal disease
  45. Secondary to severe liver disease
    Defective renal tubular reabsorption=Fanconi’s Syndrome
    Chemotherapy with 6-mercaptopurine or azathioprine – inhibit purine synthesis
    Over treatment with allopurinol
    will lead to ?
  46. Measured in heparinized plasma, serum, or urine
    Diet may affect concentration overall, but fasting not necessary.
    Specimen Requirements & Interfering Substances when measuring Uric acid
  47. Formed in deamination of amino acids during protein metabolism
    Removed from circulation & converted to urea in liver
    Toxic when free, but found in low concentrations in plasma
  48. Most common cause of abnormal ammonia levels
    Ammonia is not removed from circulation & not converted to urea
    Severe liver disease
  49. Elevated ammonia levels are _________ and are often associated with _________
    • neurotoxic
    • encephalopathy
  50. Most commonly disease seen in children
    Often preceded by viral infection treated with aspirin
    Severe fatty infiltration of liver
    May be fatal if ammonia levels remain high
    100% survival if ammonia stays below 5x normal
    Reye’s Syndrome
  51. Determination of prognosis for severe liver disease
    Determination of severity & prognosis of Reye’s syndrome
    Diagnosis of inherited deficiency of urea cycle enzymes
    Monitoring of hyperalimentation therapy
    Ammonia Clinical Application
  52. 2-step approach in which ammonia is isolated from sample & then assayed
    Direct measurement of ammonia by enzymatic method or ion-selective electrode
    Analytical methods of Ammonia
  53. Venous blood should be obtained without trauma & placed on ice immediately.
    Heparin & EDTA are suitable anticoagulants.
    Samples should be centrifuged at 0–4°C within 20 minutes of collection & plasma or serum removed.
    Patient should not smoke for several hours before collection.
    Specimen Requirements & Interfering Substances for Ammonia
  54. Elevated concentrations of ammonia are seen in following conditions:
    • Severe liver disease
    • Encephalopathy
    • Inherited deficiency of enzymes of urea cycle
  55. Analytic Methods for ammonia include?
    • Glutamate dehydrogenase
    • Direct ISE
  56. THe NPN compound present in highest concentration in the blood.
    Major excretory product of protein metabolism
    formed in liver from amino groups and free ammonia.
  57. The concentration of urea in the plasma is determined by?
    • protein content of the diet
    • rate of protein catabolism
    • renal function and perfusion
  58. measurements of urea is used to evaluate?
    • renal function
    • hydration status
    • determine nitrogen balance
    • aid in diagnosis of renal disease
    • verify adequacy of dialysis
  59. Urea is often reported in term of______ concentration?
  60. Urea concentration may be measured in?
    • Plasma
    • serum
    • Urine
  61. Specimen requirement for urea concentration determination include?
    • Plasma: avoid ammonium ions and high concentration of sodium citrate and sodium fluoride
    • No fasting is required,
    • Nonhemolyzed sample is recommended
    • specimen that cannot be analyzed within a few hours should be refrigerated
  62. Why is urea specimen must be refrigerated is cannot be analyzed within a few hours?
    because Urea is susceptible to bacterial decomposition.
  63. Elevated concentration of urea in the blood is known as?
  64. Very high plasma urea concentration accompanied by renal failure is called?
    • Uremia
    • Uremic syndrom
  65. Conditions coaching increased Plasma urea are classified according to the cause into what categories?
    • pre-renal
    • renal
    • post-renal
  66. Low protein intake Severe vomiting and diarrhea
    liver disease
     are all causes of ________ urea concentration in plasma
  67. Congestive heart failure
    Shock, Hemorrhage, Dehydration 
    Increased protein catabolism
    High protein diet.
    All are causes of _______ urea concentration in plasma, and part of ____ category .
    • Increased 
    • pre-renal
  68. Acute and chronic renal failure
    Renal disease, including glomerulonephritis and tubular necrosis are all cases of _____ urea concentration in plasma and part of ____ category
    • increased
    • renal
  69. Urinary tract abstraction  will cause _______ urea concentration in plasma and it is part of ____ category
    • increased
    • postrenal
  70. Nearly all uric acid in plasma is present as?
    monosodium urate
  71. Non specific analytical Chemical method  that requires protein removal, that is used to determine uric acid is?
    Phosphotungstic acid
  72. very specific enzymatic method that is used to analyze uric acid?
    Use Urecase
  73. enzymatic method that is readily automated where reducing agents can interfere that is used to analyze uric acid i?
    Couples enzymatic - peroxidase
  74. Enzymatic method used to analyze uric acid in which hemoglobin and xanthine interfere is?

    decreased absorbance at 293 measured
  75. proposed referenced analytical method used to measure uric acid is?
    Isotop dilution mass spectrometry
  76. Specimen requirements for uric acid collection include?
    • Heparinized serum or plasma
    • serum should be removed from cell as soon as possible
    • gross lipemia should be avoided
    • High billirubin concentration may falsly decrease results
    • Drugs: salicylates and Thiazides increase value
    • Serum may be stored in the fridge for 3-5 days 
    • EDTA or Fluoride additives should not be used
  77. gout
    increased catabolism of nucleic acid or starvation
    chronic renal disease
    treatment with cytotoxic drugs
    hemolytic and proliferative process 
    purine reach diet
    Enzyme deficiency
    Toxemia or pregnancy
    Lactic acidosis 
    Drugs and poison
    all cause ?
    abnormally increased plasma uric acid concentration
  78. Liver disease
    defective tubular reabsorbtion
    Chemotherapy with azathioprine or 6-mercaptopurine
    overtreatment with allopurinol will case uric acid concentration to ?
  79. Creatin is synthesized primarily in the liver from?
    • arginine
    • glycin
    • methionine
  80. Plasma creatinine concentration is a function of?
    • relative muscle mass
    • rate of creatine turnover
    • renal function
  81. in which reaction creatinine reacts with picric acid in alkaline solution to form red-orange chromogen?
    Jeffe reaction
  82. Acetoacetate
    are compounds that interfere  in which chemical method when measuring creatinine?
    Jeff reaction
  83. what would be a significant source of ammonia contamination in patients?
    cigarette smoke
  84. why hemolysis should be avoided when collecting a specimen for ammonia analysis ?
    because erythrocytes contain 2 to 3  times as much ammonia as plasma
  85. which anticoagulants are suitable when collecting a specimen for ammonia analysis?
    • EDTA
    • Heparin
  86. Hyperammonemia is associated with inherited deficiency of?
    urea cycle enzymes