MT

Unit Five Exam Review

General Exam Information

  • Total Number of Questions: 72

  • Duration: 2 hours

  • Testing Environment: LockDown Browser (ensures a secure testing environment by restricting access to other applications and websites during the exam)

  • Allowable Materials:

    • Scratch paper (for calculations or detailed notes)

    • Calculator (for mathematical problem-solving)

    • Pen or pencil

Exam Structure

  • Sections:

    • Three Matching Sections (likely involving terms, definitions, images, or specific test results)

    • 15 Short Answer Questions

      • Predominantly involve identification of images related to body fluids (e.g., CSF, synovial fluid), cells (e.g., epithelial cells, WBCs, RBCs), and urinalysis elements (e.g., casts, crystals, microorganisms).

    • 54 Multiple Choice Questions

      • Approximately two-thirds focus on urinalysis, covering topics from macroscopic analysis to microscopic elements, chemical tests, and related disease states.

Key Areas of Focus
1. Kidney and Nephron Anatomy

  • Understand the parts of the kidney (cortex, medulla, renal pelvis, ureters) and nephron (glomerulus, Bowman's capsule, proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), collecting duct).

  • Important to know how urine flows through the kidney: from the glomerulus, through the tubules, into the collecting ducts, then to the renal papilla, minor calyces, major calyces, renal pelvis, ureter, bladder, and urethra.

  • Recognize the functions of nephron components:

    • Glomerulus: Filters blood to form filtrate.

    • PCT: Primary site of reabsorption of nutrients (glucose, amino acids), ions, and water.

    • Loop of Henle: Establishes osmotic gradient for water reabsorption.

    • DCT: Fine tunes reabsorption and secretion based on body's needs.

    • Collecting Duct: Final site for water reabsorption and concentration of urine.

  • Comprehend the processes of reabsorption and secretion:

    • Reabsorption: Process of reclaiming essential water and solutes (e.g., glucose, amino acids, Na^+, Cl^-, HCO_3^-, water) from the filtrate back into the blood capillaries surrounding the nephron.

    • Secretion: The process of transferring waste substances (e.g., H^+, K^+, urea, creatinine, some drugs) from the blood into the urine for excretion.

2. Renal Lab Results

  • Familiarize yourself with the meaning of renal lab results:

    • BUN (Blood Urea Nitrogen): Indicator of kidney function. Urea is a waste product of protein metabolism; elevated BUN suggests impaired kidney function or dehydration.

    • Creatinine: Waste product from muscle metabolism, also used to assess kidney efficiency. Creatinine clearance is a more accurate measure of glomerular filtration rate (GFR).

  • Significance of proteins or glucose present in urine:

    • Protein in Urine (Proteinuria/Albuminuria): May indicate kidney impairment, especially glomerular damage. Albumin is the most common protein found. Can also be transient due to fever, exercise, or stress.

    • Glucose in Urine (Glycosuria): Often associated with diabetes mellitus when blood glucose levels exceed the renal threshold (approx. 160-180 mg/dL). Can also be due to renal tubular dysfunction (renal glycosuria) even with normal blood glucose.

3. Macroscopic Urine Results

  • Understand the importance of macroscopic characteristics:

    • Color: What it suggests about health. Normal is yellow (due to urochrome). Abnormal colors include:

      • Red/Brown: Presence of blood (hematuria) or hemoglobin/myoglobin.

      • Yellow-brown/Amber: Bilirubin (liver disease).

      • Green: Pseudomonas infection.

      • Orange: Certain medications (e.g., phenazopyridine).

    • Clarity: Indicates the presence of certain conditions or substances. Normal is clear. Hazy, cloudy, or turbid urine can indicate:

      • Red blood cells (RBCs).

      • White blood cells (WBCs).

      • Bacteria (infection).

      • Crystals.

      • Amorphous material.

      • Epithelial cells.

      • Mucus.

4. Renal Terminology

  • Key terms to remember:

    • Anuria: Absence of urine formation, defined as less than 50 mL in 24 hours. Often indicates severe kidney damage or obstruction.

    • Oliguria: Reduced urine output, defined as less than 400 mL in 24 hours.

    • Polyuria: Excessive urine output, typically more than 2.5 L in 24 hours. Associated with diabetes mellitus or diabetes insipidus.

    • Nocturia: Frequent urination during the night.

    • Dysuria: Painful or difficult urination, often associated with urinary tract infections.

5. Urine Strip Reactions

  • Knowledge of specific chemical test responses related to urine strip testing:

    • Nitroprusside Reaction: Related to ketone testing. Specifically detects acetoacetate and, to a lesser extent, acetone. Does not detect beta-hydroxybutyrate, which is the most prevalent ketone in diabetic ketoacidosis.

    • Ehrlich's Reaction: Used for detecting urobilinogen, an indicator of liver function or hemolytic conditions.

    • Double Indicator Reaction: Involves indicators like methyl red and bromothymol blue to measure pH changes, providing a range for urine pH.

  • Understanding which ketones lead to a positive test (acetoacetate and acetone) and the protein responsible for a positive result on protein strips (primarily albumin, which reacts with the tetrabromophenol blue indicator).

6. Confirmatory Tests

  • Important confirmatory tests to know:

    • Bilirubin Test: Such as the Ictotest tablet method (diazo reaction), for detecting icterus (jaundice) or liver disease.

    • ACE Test (Acetest): Tablet test for confirming the presence of ketones (acetoacetate and acetone) in higher concentrations than the strip can detect.

    • Clinitest: Copper reduction test for detecting reducing sugars in urine (e.g., glucose, galactose, fructose, lactose). Important for screening for galactosemia in infants, as it detects non-glucose reducing sugars.

7. Urine Element Identification

  • Practice analyzing images and identifying elements:

    • Pay attention to arrows in diagrams to indicate the specific parts being referenced (e.g., specific cells, casts, crystals).

    • Additional questions may involve:

      • Identification of urine crystals (e.g., uric acid, calcium oxalate, triple phosphate) and their associated pH levels (e.g., uric acid and calcium oxalate in acidic urine; triple phosphate in alkaline urine).

      • Clinical significance of squamous epithelial cells (usually contamination, not pathological) versus renal tubular epithelial cells (significant, indicates tubular damage) and other findings (e.g., RBCs, WBCs, casts, bacteria, yeast, parasites, mucus).

8. Urine Specimen Types

  • Familiarize with various urine collection methods:

    • First Morning Specimen: The most concentrated specimen, ideal for microscopic analysis, specific gravity, protein detection, and nitrite testing, as it reflects the kidney's ability to concentrate urine over time.

    • Clean Catch Method (Midstream Urine): Minimizes contamination from external genitalia by collecting the middle portion of the voided urine after cleaning the area. Primarily used for bacterial cultures.

    • Random Urine Samples: Less consistent, useful for routine screening tests with less strict collection requirements.

    • Catheterization: Involves inserting a catheter into the bladder to obtain a sterile sample, used when clean catch is difficult or a sterile sample is critical, but carries a risk of introducing infection.

    • Suprapubic Aspiration: Sterile, invasive collection by needle directly into the bladder through the abdominal wall, primarily for anaerobic cultures in infants or when other methods are not feasible.

    • 24-hour Collection: Required for quantitative analysis of analytes like creatinine clearance, total protein, and hormones, providing an average excretion rate over a full day.

9. Disease States and Urinary Elements

  • Understand disease correlations with urine findings:

    • Red Blood Cell Casts: Indicative of glomerulonephritis, severe glomerular damage, or vasculitis.

    • White Blood Cell Casts: Indicate pyelonephritis (kidney infection) or acute interstitial nephritis.

    • Clumped White Blood Cells: Suggestive of acute infection or severe inflammation within the urinary tract.

    • Bacteria in Urine: Suggestive of a urinary tract infection (UTI), often accompanied by WBCs and positive nitrite/leukocyte esterase.

    • Hyaline Casts: Can be non-pathologic (due to dehydration, exercise, fever) or signify early renal disease.

    • Granular Casts and Waxy Casts: Generally indicate more severe, chronic renal disease or stasis of urine flow.

10. Inborn Errors of Metabolism (IEM)

  • Key diseases to study:

    • Phenylketonuria (PKU): An autosomal recessive disorder caused by a deficiency in the enzyme phenylalanine hydroxylase, leading to the accumulation of phenylalanine. If untreated, it causes severe intellectual disability. Detected by newborn screening (Guthrie test).

    • Alcaptonuria: An autosomal recessive disorder characterized by a deficiency of homogentisic acid oxidase, causing homogentisic acid to accumulate in the body. Urine turns black upon exposure to air, and can lead to ochronosis (darkening of cartilage and connective tissue) and early onset arthritis.

  • Focus on unique symptoms associated with each condition.

11. Case Studies

  • Review case studies that involve:

    • Interpreting patient results for diagnosis and management.

    • Understanding interference by substances like ascorbic acid (Vitamin C), which can cause false-negative results in certain tests (e.g., bilirubin, nitrite, blood) on reagent strips by acting as a reducing agent.

12. Body Fluids Section

  • Focus on the following key concepts:

    • Transudates vs. Exudates: Understanding the difference and being able to categorize fluid types based on definitions.

      • Transudates: Result from systemic conditions (e.g., congestive heart failure, cirrhosis, nephrotic syndrome) that alter hydrostatic or oncotic pressure. They are typically clear, have low specific gravity (<1.015), low total protein (<3.0 g/dL), and low LDH.

      • Exudates: Result from local factors (e.g., inflammation, infection, malignancy) that increase capillary permeability. They are often cloudy, have high specific gravity (>1.015), high total protein (>3.0 g/dL), and high LDH.

    • CSF (Cerebrospinal Fluid): Critical understanding of tube appearance and the order of collection:

      • Tube 1: Chemistry testing (e.g., protein, glucose) and immunology.

      • Tube 2: Microbial analysis (e.g., cultures, Gram stain).

      • Tube 3: Hematology (cell count and differential).

      • Tube 4: Special studies or tissue banking.

      • This order helps minimize false positives from a traumatic tap (blood from the needle stick usually clears by Tube 3).

    • Recognize indicators of specific conditions based on CSF appearance (e.g., bloody or yellow):

      • Bloody: Can be due to a traumatic tap (blood clears with successive tubes) or subarachnoid hemorrhage (blood is uniformly distributed, xanthochromia may develop).

      • Xanthochromic (yellowish): Indicates presence of bilirubin from lysed red blood cells (old hemorrhage) or high protein.

      • Cloudy/Turbid: Suggests presence of WBCs (meningitis), bacteria, or high protein.

13. CSF Testing Parameters

  • General parameters in CSF analysis:

    • Protein Levels: Normal range is 15-45 mg/dL. Elevated levels may indicate various central nervous system diseases (e.g., meningitis, multiple sclerosis, hemorrhage, CNS tumors).

    • Glucose Levels: Normal is typically 60-70\% of plasma glucose concentration. Decreased levels are seen in bacterial, fungal, and tuberculous meningitis (microorganisms consume glucose).

    • Lactate: Important for diagnosing infections or metabolic disorders. Elevated in bacterial, fungal, and parasitic meningitis, and cerebral ischemia. Normal in viral meningitis.

    • LDH (Lactic Dehydrogenase): Elevated levels can indicate tissue breakdown or bacterial meningitis.

    • Cell Count and Differential: Normal is 0-5 WBCs/\mu L (adults). Elevated WBCs (pleocytosis) are seen in meningitis. A differential count helps distinguish types (e.g., neutrophils in bacterial, lymphocytes in viral).

14. Anatomy and Terms for Specific Fluids

  • Study origins and characteristics of various body fluids:

    • Synovial Fluid: Found in joint cavities, provides lubrication and nutrient transport. Analysis helps differentiate inflammatory (e.g., rheumatoid arthritis, gout) from non-inflammatory (e.g., osteoarthritis) arthritis and infections.

    • Serous Fluids: Includes pleural fluid (surrounding lungs), pericardial fluid (surrounding heart), and peritoneal fluid (abdominal cavity). These fluids are ultrafiltrates of plasma and their analysis helps classify effusions as transudates or exudates.

  • Viscosity and appearance distinctions among different fluids must be noted:

    • Synovial fluid is highly viscous due to hyaluronic acid. Loss of viscosity can indicate inflammation.

    • Appearance can range from clear (normal) to cloudy, bloody, or milky, each suggestive of different pathologies.

15. Crystals in Synovial Fluids

  • Identification of synovial fluid crystals:

    • Ability to differentiate types of crystals under polarized light microscopy and understand their clinical significance.

    • Monosodium Urate (MSU) crystals: Associated with gout. Typically needle-shaped and exhibit strong negative birefringence (yellow when parallel to the compensator).

    • Calcium Pyrophosphate Dihydrate (CPPD) crystals: Associated with pseudogout. Rombooid- or rod-shaped and exhibit weak positive birefringence (blue when parallel to the compensator).

16. Case Studies in Body Fluids

  • Expected questions involve understanding real patient cases:

    • Example: Vaginal Wet Prep: Identifying components such as clue cells (indicative of bacterial vaginosis), budding yeast and pseudohyphae (for candidiasis), and motile trichomonads (for trichomoniasis), and their clinical significance.

17. Miscellaneous Body Fluids

  • Key body fluids to know:

    • Vaginal Fluid: Analysis includes identifying common infections (bacterial vaginosis, yeast infections, trichomoniasis), pH, and a whiff test for diagnosis.

    • Stool Analysis: Testing for gastrointestinal infections (e.g., bacteria, viruses, parasites), occult blood (indicating bleeding), fecal fat (for malabsorption syndromes), and leukocyte detection (for inflammation).

    • Amniotic Fluid: Understanding its significance during pregnancy and delivery; tested for fetal lung maturity (e.g., L/S ratio, presence of phosphatidylglycerol (PG)), chromosomal abnormalities, infection, and neural tube defects (e.g., alpha-fetoprotein (AFP)).

    • Semen Analysis: Evaluating male fertility and reproductive health indicators based on parameters such as sperm count, motility, morphology, viability, pH, liquefaction time, and viscosity.