Kidney Function Tests and Glomerulonephritis
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Questions and Answers

What components are included in the osmolality equation for determining osmolarity?

  • [Na+], [Glucose], [BUN] (correct)
  • [Urea], [BUN], Albumin
  • [Creatinine], [Cholesterol], [Triglycerides]
  • [Na+], Creatinine, [Cholesterol]

    • In prerenal azotemia, how does urea respond in comparison to creatinine?

  • Both are elevated equally. (correct)
  • Urea increases while creatinine decreases.
  • Creatinine increases while urea remains constant.
  • Urea decreases while creatinine remains constant.

    • Which condition is most likely characterized by rapid onset and presented with hematuria and proteinuria?

  • Nephrotic Syndrome
  • Chronic Glomerulonephritis
  • Prerenal Azotemia
  • Acute Glomerulonephritis (correct)

    • In Nephrotic Syndrome, what lab findings are typically observed in plasma?

    <p>Increased total cholesterol, Increased triglycerides</p> Signup and view all the answers

    What false results can the Jaffe Reaction yield due to hemolysis?

    <p>False increase in creatinine</p> Signup and view all the answers

    What is the reference range for Blood Urea Nitrogen (BUN)?

    <p>6-23 mg/dL</p> Signup and view all the answers

    Which method is NOT used to measure Uric Acid levels?

    <p>HPLC method</p> Signup and view all the answers

    What can cause a false increase in creatinine measurement using the Jaffe method?

    <p>Presence of ketones</p> Signup and view all the answers

    What is a consequence of increased blood urea, known as azotemia?

    <p>Uremia</p> Signup and view all the answers

    Which condition is associated with increased levels of uric acid leading to gout?

    <p>Renal calculi</p> Signup and view all the answers

    What is the primary function of antidiuretic hormone (ADH) in relation to water?

    <p>Increases water reabsorption in the collecting ducts</p> Signup and view all the answers

    How does aldosterone affect potassium levels in the body?

    <p>It promotes potassium excretion and sodium reabsorption</p> Signup and view all the answers

    What triggers the release of renin in the kidney?

    <p>Decreased blood flow and plasma sodium concentration</p> Signup and view all the answers

    What is the role of erythropoietin in the body?

    <p>To promote red blood cell production</p> Signup and view all the answers

    Which of the following substances is primarily regulated by the renin-angiotensin-aldosterone system?

    <p>Sodium</p> Signup and view all the answers

    What is the function of 1,25-Dihydroxy vitamin D3 in the body?

    <p>Determines phosphate and calcium balance</p> Signup and view all the answers

    Which of the following statements accurately describes prostaglandins in relation to renal function?

    <p>They increase renal blood flow and oppose renal vasoconstriction.</p> Signup and view all the answers

    Creatinine levels in the blood are most commonly used to assess what aspect of health?

    <p>Renal function</p> Signup and view all the answers

    What is primarily responsible for maintaining osmotic pressure in the body?

    <p>Sodium</p> Signup and view all the answers

    Which condition is associated with an increased anion gap?

    <p>Diabetes mellitus complications</p> Signup and view all the answers

    What indicates the presence of an unmeasured substance in the body?

    <p>Increased osmolal gap</p> Signup and view all the answers

    Which substance is NOT typically a cause for decreased anion gap?

    <p>Diabetes mellitus</p> Signup and view all the answers

    Which of the following best represents the total carbon dioxide (CO2) composition in the bicarbonate/carbonic acid buffering system?

    <p>95% bicarbonate, 5% dissolved CO2</p> Signup and view all the answers

    Study Notes

    Kidney Function Tests

    • Osmolality Equation: (1.86 * [Na+]) + [Glucose]/18 + [BUN]/2.8 + 9 = Osm/L

    • Creatinine and BUN: Should be elevated proportionally if there is a kidney problem.

    • Prerenal Azotemia: Increased BUN without increased creatinine.

      • Decreased renal blood flow: CHF, shock, decreased renal blood volume.
      • Increased protein catabolism: High protein diet, fever, upper GI bleeding.
      • Dehydration: Urea moves with water; less water excretion → less urea excretion.

    • Jaffe Reaction: Creatinine + Alkaline picrate → Red-orange.

      • False increase: Hemolysis, ketones, glucose, proteins, ascorbic acid
      • False decrease: Icterus.

    • Kinetic Jaffe: Measures reaction rate.

      • More specific.
      • Only ketones interfere.

    Glomerulonephritis

    • Acute Glomerulonephritis: Rapid onset.

      • Inflammation due to GAS, drug toxicity, SLE.
      • Hypertension, edema.
      • Urine Lab Findings: Hematuria, proteinuria.
      • Plasma Lab Findings: Increased: Creatinine, Urea, K+. Decreased: Na+, CO2, Albumin.

    • Chronic Glomerulonephritis: Slow onset inflammatory response.

      • May be asymptomatic (only slightly decreased GFR).
      • Urine Lab Findings: Slight hematuria, proteinuria.
      • Plasma Lab Findings: Increased: Urea, creatinine.
      • Gradual hypertension, renal failure with lab findings similar to acute form.

    Nephrotic Syndrome

    • Increased Glomerular basement membrane permeability.
    • Generalized edema.
    • Urine Lab Findings: Severe proteinuria
    • Plasma Lab Findings: Increased: Alpha-2-globulins (AMG), Total Cholesterol, Triglycerides. Decreased: Albumin and Alpha-1-globulins.

    Hormones

    • Antidiuretic Hormone (ADH): Released in distal convoluted tubule and collecting ducts; increases water reabsorption.

      • Released from posterior pituitary in response to increased plasma osmolality and decreased intravascular volume.
      • Increases permeability of distal convoluted tubules and collecting ducts to water, causing increased water reabsorption.
      • Increased plasma osmolality: Thirst and increased ADH secretion → Increased [urine] osmolality, Decreased urine output.
      • Decreased plasma osmolality: Decreased ADH secretion → Decreased [urine] osmolality, Increased urine output.
      • Diabetes insipidus (neurogenic): Decreased ADH secretion/action → Dehydration.

    • Aldosterone (ALD): Released by distal convoluted tubule.

      • Increases Na+ reabsorption; K+ and H+ secretion.
      • Regulation by RAS (regulates BP).
      • Decreased plasma Na+ and blood flow: Increased ALD secretion.
      • Renin-Angiotensin: Regulates blood pressure and ALD secretion. Decreased BP → Increased ALD.
      • Potassium: Reabsorbed and excreted by distal convoluted tubule and collecting ducts; excretion controlled by aldosterone.

    • Renin: Regulates ALD secretion.

      • Decreased BP: Increased RAS → Increased ALD.
      • Renin catalyzes synthesis of angiotensin.
      • Sodium: Controlled primarily by renin-angiotensin-aldosterone hormonal system, excreted from kidney.

    • Erythropoietin: RBC production.

      • Chronic renal failure: Anemia.
      • Acts on erythroid progenitor cells in bone marrow, increasing number of RBCs.

    • 1,25-Dihydroxy vitamin D3: Active form of vitamin D.

      • Determines phosphate and calcium balance and bone calcification.

    • Prostaglandins: Increase renal blood flow, sodium and water excretion, and renin release.

      • Oppose renal vasoconstriction.

    Creatinine

    • Waste product in creatine phosphate (high energy source) production.
    • Measured to assess renal function.
    • Proportional to muscle mass.
    • Can be used for TDM, and Delta check.
    • Enzymatic methods: Creatinase, creatine hydrolase.
      • Increased specificity compared to both Jaffes.
    • False Increase: Hemolysis, ketones, glucose, protein, ascorbic acid (Jaffe). Ketones (Kinetic Jaffe)
    • False Decrease: Icterus.
    • Reference Range: 0.6-1.1 mg/dL.
    • Increased: ERSD (plasma)
    • Corrected Creatinine Clearance: Cu/Cs * Total volume/1440 * 1.73/Surface area.

    Blood Urea Nitrogen (BUN)

    • End product of protein catabolism: AA → NH3 → Urea cycle → Urea.
    • Increased urea: Azotemia → uremia.
    • Methods:
      • Urease: Urea → NH4+ + HCO3-.
      • Coupled enzyme reaction: NADH → NAD+ (rate of disappearance of NADH measured).
      • Indicator dye: (ammonia + pH indicator).
      • Conductimetric.
    • Interferences: Increased ammonia: Increased blood ammonia, contaminated reagents, glassware, water.
    • Specimen: Serum, plasma, pre-diluted urine. No anticoag that inhibit urease (no NaF, Na-citrate).
    • Reference range: 6-23 mg/dL.

    Uric Acid

    • End product in purine metabolism. Dietary and endogenous nucleic acids. Liver converts purines → uric acid.

    • Methods:

      • Uricase: Uric acid + O2 → allantoin + CO2 + H2O2.
      • Couple enzymatic: H2O2 + Reduced chromogen (colorless) → Oxidized chromogen (colored) + H2O.

    • Interferences: False decrease: Bilirubin, ascorbic acid.

    • Increased:

      • Gout: Urates precipitates in joint fluids, renal calculi. Males 30-50 years.
        • Primary causes: Increased purine production.
        • Secondary causes: Alcohol and drugs, increased dietary intake.
      • Increased cell breakdown: Chemotherapy, leukemia.
      • Chronic renal disease: uric acid excretion.

    • Decreased: Fanconi syndrome: Defective tubular reabsorption.

      Electrolytes

    • Osmotic pressure: Primarily maintained by Na+.

    • Osmolal gap: Measured - Calculated.

      • RR: < 10 mOsm/kg.
      • Increased osmolal gap: indicates unmeasured substance is present (alcohol, ketone).

    • Anion gap: Difference between unmeasured anions and unmeasured cations:

      • (Na + K) - (Cl + HCO3/CO2) (10-20 mmol/L).
      • (Na) - (HCO3/CO2 + Cl) (7-16 mmol/L).

    • Increase: Increased unmeasured anions OR decrease unmeasured cations.

      • Increased anion gap metabolic acidosis.
      • Methanol
        • Uremia
        • DKA
        • Paraldehyde
        • Iron, Isoniazid, ibuprofen
          • Lactic acidosis
        • Ethylene glycol, ethanol
        • Salicylates

    • Decreased: Decreased unmeasured anions OR increased unmeasured cations.

      • Hypoalbuminemia, hypergammaglobulinemia.

    Membranes

    • Na+: Na ionophore, Na sensitive glass.

    • K+: Valinomycin.

    • Cl-: Solid-state- AgCl2 or Ag Sulfide (Halogen).

    • Interference: Protein build-up.

      Bicarbonate/carbonic acid

    • Most important buffering pair.

    • Total CO2:

      • Bicarbonate (95%).
      • Dissolved CO2 (5%).
      • Carbonic acid.

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    Description

    Explore the essential concepts of kidney function tests, including the osmolality equation and the Jaffe reaction. Learn about prerenal azotemia and acute glomerulonephritis, along with their causes, symptoms, and lab findings. This quiz will enhance your understanding of renal function and its clinical implications.

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