Lab diagnosis 2
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What tests are affected by hemolysis? Which is the most important? Why?
- Potassium, LDH, Phosphorous
- Potassium - high or low amounts will cause cardiac arrest (small range)
What molecules must be maintained at critical levels in the blood? (Too much or too little will cause problems)
Glucose, Potassium, Calcium, Sodium
What molecules indicate critical problems if there is too much in the blood?
CK - 1 and CK - 2 and Bilirubin (infants)
What tests do you have to fast before?
What is a BUN test?
Blood urea nitrogen
What were the first instruments to analyze blood samples?
SMA 6/60, SMA 12/60 and SMAC
What two methods are used for most of a biochemical profile?
Colorimetry and Enzymes
How does Colorimetry work?
Based on Beer-Lambert Law: Color is directly proportional to concentration
What are the two ways enzymes can be measured?
- Rate at which substrate is converted to product
- Rate at which a substrate is depleted
What does Electrophoresis do?
Separate similar substances into individual components
What are the 5 tests electrophoresis is used for?
- Hemoglobin - detecting abnormal forms
- Protein - Total protein or serum protein electrolyte (TPE or SPE) ex. multiple myeloma
- Immunophoresis (immunofixaton electrophoresis) (IFE or IEP) - done when their is an immunoglobulin spike in SPE
- Lipoprotein - ex. hyperlipidemia
- Western blot - confirmatory test (3 bands)
What are the immunoglobulins? Which is the most prevalant? Which arrives first? Which lasts the longest?
- IgG - 85%, 2nd to arrive, lasts longest
- IgM - largest, first to arrive
What are the 5 types of antigen-antibody complex formation tests?
- Precipitation tests
- Agglutination tests
- Neutralization tests
- Fluorescent antibody tests (Immunofluorescence)
- Complement fixation
What is the RPR a screening test for? What type of test is it?
What is immunoprecipitation?
A newer version of precipitation in which there is a well in the center and arcs will form around it if a reaction occurs
What is another name for agglutination tests? What is the most common type? What is a common example?
- Agglutination Inhibition/particle inhibition
- Latex agglutination
- Heterophile antibody test (for mono)
What are three nutralization tests and what do they test for?
- ASO titer (anti-streptolysin O) - strep
- Anti-DNAaseB (ADB) - strep
- AHT (antihyaluronidase) - strep
What are the 4 most common strep pathologies?
- Rheumatic fever
- Acute Post strep Glomerulonephritis
- Erythems nodosum
- Acute bacterial endocarditis
What is erythema nodosum? What can cause it?
- red nodes on legs (usually pre-tibial)
- Strep, mono, birth control, chron's
What are the two most common Fluorescent antibody tests and what do they test for?
- FTA (Fluorescent treponemal antibody) - syphilis
- FANA (Fluorescnet anti-nuclear antibody) - SLE
What test was done for SLE before FANA?
dsDNA antibody (ds = double stranded)
What is a complement fixation test?
- Tests for the presence of an antibody or antigen
- Negative test --> complement binds to and lyses sheep RBCs
- Positive test --> complement binds to antibody-antigen complex and sheep RBC's remain intact
What is RIA?
Old antigen-antibody test, replaced by EIA (faster, more sensitive)
What is ELISA?
- Enzyme-linked immunosorbent assay
- Screening test for many antibodies (strep, HIV, hepatitis)
- Antibody in well, immunoglobulin binds then antibody with detection marker binds
What is Nephelometry?
Measures the rate of turbity which indicates the quantity of serum proteins (highest when antigen = antibody concentration) - particles scatter light --> positive
What is Western blot?
- Confirmatory test for many antibodies
- Electrophoresis (color reaction occurs)
What tests indicate a musculoskeletal problem?
- Calcium (#1)
- Uric acid
- Alkaline phosphatase (#2)
What is calcium an indicator of?
Parathyroid function and various malignacies
What are the 3 forms of calcium?
- 50% free/ionized
- 45% bound
What does acidosis promote?
Increased ionized/free calcium
What does PTH do to calcium blood levels?
What does calcitonin do to blood levels of calcium?
Decreases (puts it in the bone)
How does estrogen affect calcium?
Puts calcium in bone
How will hyperthyroid or hyper adrenal glands affect calcium?
hypocalcemia, bone decalcification
Causes of Hypercalcemia?
- Primary hyperparathyroid (#1)
- Malignancy (#2)
- Metastatic bone tumors
- PTH producing tumors (lungs or renal)
- Vitamin D intoxication
What are the symptoms of hypercalcemia?
- Neurological (irritability, memory loss)
- Peptic ulcers
- Bone lesions
- Kidney stones
Causes of hypocalcemia?
- Malnutrition (#1)
- Hypoalbuminemia (#1)
- Renal disease/failure
- Secondary hyperparathyroidism
- Vitamin D deficiency
What is a major cause of secondary hyperparathyroidism?
What are the symptoms of hypocalcemia?
- Increased neuromuscular excitability
- Altered cardiac function
What are three signs of Tetany?
- Chvostek's - tap on parotid gland near facial nerve --> face contracts if positive
- Main d'accoucher - tetany of wrist
- Trousseau's - blood pressure cuff causes involuntary spasm of hand
What are some follow up tests for calcium?
- Ionized calcium test
- PTH assay
- X-ray or protein electrophoresis - multiple myeloma
- Chest x-ray if coughing - sarcoidosis, TB
- Cortisol - Cushings
- Vitamin D levels
How do Calcium and phosphorus levels affect each other?
- When one goes up, the other goes down (body tries to maintain constant product of the two)
- Exception - vitamin D deficiency
Causes of Hyperphosphatemia?
- Renal failure/osteodystrophy
- Secondary hyperparathyroidism
- Excess vitamin D intake
Causes of hypophosphatemia?
- Primary hyperparathyroidism
- Malabsorption syndromes
What are the two main pathologies with high uric acid levels?
Gout (#2) and Renal Calculi (#1)
Causes of Hyperuricemia?
- Excess purine consumption
- Excessive cell breakdown/catabolism on nucleic acids
- Excessive cell production and destruction (ex. leukemia, multiple myeloma, P. vera)
- Renal disease (inability to excrete urea)
What drugs can cause hypouricemia?
- Allopurinol - purine blocker
- Asprin - purine blocker
- Colchicine - excretes purines
Primary vs. secondary gout?
- Primary - from overproduction of uric acid or impaired renal tubular excretion
- Secondary - excessive uric acid from increased nucleic acid turnover or acquired renal problems decreasing excretion
What are the three main isoenzymes of alkaline phosphatase (ALP)?
- Bone (osteoblasts) (highest concentration) (#1)
- Liver (#2)
Causes of increased ALP?
- Liver infection/cancer/disease
- Bone pathologies (including fractures)
- Last tri of pregnancy
What is septic arthritis?
Infectious arthritis - bacterial invasion of a joint --> inflammation, destruction
Labs for septic arthritis?
Arthrocentesis (pus in joint fluid), increased WBC count, C-reactive protein and ESR
What is gout?
Gouty arthritis - metabolic disease where urate deposits in joints, usually feet and legs
Labs for gout?
- Arthrocentesis (monosodium urate crystals)
- Uric acid blood levels increased
What is osteoarthritis?
- Most common arthritis
- Deterioration of joint cartilage, formation fo reactive new bone at margins and subchondral areas
What is osteomyelitis?
Pyogenic bone infection that can be acute or chronic, can stay local or spread
Labs for osteomyelitis?
increased WBCs, ESR, C-reactive protein, blood cultures
Differential diagnosis for osteomyelitis?
- Rheumatic fever
- Bone fracture
What is Paget's?
- Osteitis deformans
- Slow progressive metabolic bone disease
- Initial excess resorption of bone followed by bone formation
- Affects males > 40 years
Labs for Paget's?
- Serum alkaline phosphatase
- Urine: 24 hour hydroxyproline
- X-ray/bone scan
What is muscular dystrophy?
A group of congenital disorders characterized by progressive symmetrical wasting of skeletal muscles without neural or sensory defects
What are the two main types of muscular dystrophy?
- Duchenne's - childhood form, deficiency in dystrophin (protein)
- Limb girdle - affects upper arms and legs, cardiovascular problems
Tests for muscular dystrophy?
- CK-3 (CK-MM) - elevated
- Muscle testing
- Pre-natal testing
What is osteoporosis?
Metabolic bone disorder in which the rate of bone resorption accelerates and formation decreases
Labs for osteoporosis?
- Calcium - normal
- Phosphorous - normal
- Alkaline phosphatase - normal
- PTH - possible elevation
- Urine - collagen
- Dexa scan
What tests on the biochemical profile indicate a problem with the liver?
- Alkaline phosphatase
- AST (SGOT)
- ALT (SGPT)
- Albumin/total protein
What follow up liver tests are there?
- Bile salts/acids
- Vitamin K/PT/PTT
- Alpha fetoprotein
- Alpha 1-antitrypsin
- BSP dye
- Hepatitis tests
What is AST? What do elevated levels of AST indicate?
- Aspartate aminotransferase or Serum Glutamin Oxaloacetic transaminase
- Indicates Liver (hepatitis, infectious mono, hepatic metastasis, tumor, alcoholism) or heart (MI, surgery) problem
What is ALT? What organ has the highest concentration of ALT? What would a greatly increased ALT indicate? What would a moderately increased ALT indicate?
- Alanine aminotransferase or Serum Glutamic Pyruvic transaminase
- Liver has hghest concentration of ALT
- Significant increase: Hepatitis, hepatic necrosis, hepatic ischemia
- Moderate: Cirrhosis, cholestasis (bile duct is blocked), hepatic tumor, obstructive jaundice
What issues are indicated by AST/ALT >1?
Alcoholic cirrhosis, liver congestion, metastasis to liver
What issues are indicated by AST/ALT <1?
Acute hepatitis, viral hepatitis, infectious mono
What enzyme is most sensitive to alcohol usage?
What does an increase in SGGT indicate?
- Liver disease
- Alcohol intake
- obstructive jaundice
- Meds: Dilantin and Phenobarb
How would you DDX liver disease from skeletal disease?
- Both: Increased AST, Alk Phos, LDH
- Liver only: Increased ALT, SGGT, Bilirubin
What is LAP? What does an increased LAP indicate?
- Leucine Aminopeptidase
- Liver disease
How many LDH isoenzymes are there? What is the most abundant? What does each indicate?
- LDH 2 is the most abundant
- LDH 1 indicates MI or renal
- LDH 2 indicates reticuloendothelial
- LDH 3 indicates lungs or lymphocytes
- LDH 5 indicates Liver, skeletal muscle
What is a flipped or reversed LDH? What does it indicate?
LDH 1 > LDH 2 --> MI
Which LDH will be elevated during strenous exercise?
1,2 and 5
What type of bilirubin is higher in the blood?
What is another name for unconjugated bilirubin?
Where is bilirubin conjugated?
Where does bilirubin come from?
RBC breakdown (porphyrin ring of heme)
What is another name for prehepatic jaundice? What is its cause?
- Increased RBC breakdown (hemolytic anemia, sickle cell, Pernicious anemia, erythroblastosis fetalis/hemolytic anemia of the newborn, Resolution of large hematoma, hepatitis, cirrhosis, neonatal hyperbilirubinemia, Gilbert's disease/Crigler-Najjar syndrome G6PD deficiency)
What is kernicterus?
Accumulation of bilirubin in baby's brain causing mental retardation
A person with bilirubinuria and elevated direct probably has?
Post-hepatic jaundice (obstructive) (gallstones/ cholelithiasis, pancreatic carcinoma, tumors, duct obstruction/cholestasis) - failure to excrete conjugated bilirubin
Neonatal jaundice gives increased?
Unconjugated bilirubin, cause by immature liver (hepatic jaundice)
Hemolytic ds of newborn gives increased?
Unconjugated bilirubin, mom is breaking down baby's RBCs (Rh- mom and Rh+ baby)
What type of bilirubin is increased in Gilbert's ds? What is it commonly misdiagnosed as?
What type of bilirubin can be found in the urine? Why?
Conjugated, it is water soluble
Elevated direct and indirect bilirubin can occur wit?
Liver damage (hepatitis, alcoholism, cancer)
Increased urobilinogen in the urine reflects increased _____ in the blood?
Unconjugated bilirubin (the U's go together)
What will the urine findings be in a liver problem?
Increased urobilinogen and presence of conjugated bilirubin
What fraction of bilirubin is conjugated?
- 15 to 20%
- 70 to 85% is unconjugated
What does decreased albumin lead to?
What can decrease albumin levels?
Malnutrition/malabsorption (Crohn's, Whipple's), Liver disease, inflammatory diseases, 3rd degree burns, protein-losing kidney disease (nephrotic syndrome)
What can increased albumin levels?
Are PT/PTT and Vit K used for liver testing?
No, but they will be affected by many liver pathologies
What clotting factors are vit. K dependent? What clotting pathways are affected?
- 2, 7, 9, 10
- Intrinsic, Extrinsic and common
What clotting factors are in the intrinsic pathway? extrinsic? common?
- Intrinsic: 9,8,11,12
- Extrinsic: 3,7
- Common: 1,2,10
What is the problem with testing for ammonia?
Ammonia is very volatile, must be placed on ice right away
What causes increased ammonia levels?
- Advanced liver failure:
- Primary hepatocellular disease
- Portal hypertension
- Severe heart failure with congestive hepatomegaly
- Reyes syndrome
- Hepatic encepalopathy
- Hepatic coma
- Genetic metabolic disorder of urea cycle
What is Reyes syndrome?
Brain and liver damage caused by asprin in young children
What happens if bile acids/salts are decreased?
- Gallstones (cholesterol precipitates)
- Impaired fatty acid absorption
What is AFP? What is it used for?
- Alpha-fetoprotein - made by fetal liver and yolk sac
- Pre-natal testing and detection of liver cancer
What is AAT? What does it do?
- Alpha 1-antitrypsin
- Protein made by the liver which keeps protesases from destroying the lungs and liver
What does a deficiency in AAT cause?
- Emphysema (early onset, panacinar, more in lower 1/3rd of lung)- proteseases make holes in cells --> decreased surface area for oxygen exchange forming an air bulla/blister
- Low serum proteins
- Neonatal respiratory distress sydrome
What is CEA? What is it an indicator for?
- Carcinoembryonic antigen
- Tumor marker (particularly colon and breast)
What are acute phase reactants? Which is abnormal?
- Proteins which increased in the liver during inflammation
- C-reactive protein is not normally present
What are the most common types of hepatitis?
- Viral (IV drugs, STD)
How is hepatits spread?
- Fecal-oral (A and E)
- Blood borne (B and C)
Which immunoglobulin is the 1st to be made? Which one lasts the longest?
- IgM is first
- IgG is longest
What are the symptoms and lab findings for hepatitis?
- Fever, flu, possible jaundice
- Bilirubin, LDH, SGGT, ALT, AST and ALP are elveated, neutropenia, lymphopenia followed by lymphocytosis
How contagious are you when you are showing symptoms of hepatitis?
- Decreasing contagiousness the longer you have symptoms (peak of contagiousness comes before symptoms show)
- Contagious when have antigens not antibodies
What is another name for HAV? What is another name for HBV?
- Infectious hepatitis
- Serum hepatitis (Dane particle)
What are the parts of hepatitis B? Which one is in the gap period?
- C (core), E, S (surface)
- C is in the gap or window period or serological negative period
What is the seroconversion period?
Period when antibodies (HBsV) become present
What tests are included on a hepatitis panel in order of production?
HBsAg, HBeAg, HBcAb, HBeAb, HBsAb
What does a positive HBsAg indicate?
- 1st indicator of infection (acute)
- Person is infectious
- Chronic carrier
What does a positive HBsAg indicate?
- Previous exposure
What does a postive HBcAb indicate?
- Past infection
- 1st antibody to appear
What does a positive HBeAg indicate?
- Index of infectivity (highly contagious)
- Early and active HBV
What does a positive HBeAb indicate?
- Low infectivity
- Acute phase is over
Which hepatitis B test will distinguish between acute infxn, vaccination and chronic?
Core antibody (HBcAb)
What tests are positive for Acute HBV?
What tests are positive in a vaccination?
What tests are positive after recovery from acute HBV?
- Anti-HBc (IgG)
- Possibly Anti-HBe
What tests are positive for chronic HBV low infectivity?
- Anti-HBc (IgG)
What tests are positive for chronic HBV high infectivity?
What tests are used for HCV?
- Core antigen
What is liver cirrhosis?
- Chronic hepatic disease, destruction and fibrotic regeneration (note: fibrotic tissue is not functional)
- Caused by alcohol or other liver infection/damage
What labs are increased in liver cirrhosis?
What is the most common cause of portal hypertension? Other cuases?
- Cirrhosis is most common
- Budd Chiari syndrome
- Portal vein thrombosis
What is budd chiari syndrome?
hepatic venous or inf. vena cava is obstructed --> spider web venous collaterals form on skin and on x-ray, ascites, hepatomegaly, abdominal pain, esophageal varices
What are the signs of hepatocellular failure?
- Hepatic encephalopathy
- Bleeding diathesis (susceptible to hemorrhage)
What is hepatic encephalopathy?
Chronic liver disease interfers with ammonia catabolism and ammonia enters circulation and goes to brain, causing damage
What labs will be elevated for hepatic encephalopathy?
Ammonia, bilirubin, PT
What is another name for wilson's disease? Symptoms?
- Hepatolenticular disease
- Excess copper retention:
- Kayser-Fleicher rings (lenticular opacities) - only present when ds has progressed beyond the liver
- Hepatic disease
- Neurological changes
What is the most common symptom of gallbladder disease?
nausea and vomiting
What is cholelithiasis?
Gall stones (calculi) - 90% of all gallbladder ds
What is choledocholithiasis?
Gallstones in the common bile duct causes obstruction --> jaundice, persistent itching, retention of bile salts
What is cholecystitis?
inflammation of gallbladder
What is gallstone ileus?
gallstone ulcerates through gallbladder into intestine and causes obstruction
What is biliary cirrhosis?
Ascending infection of the biliary system leads to obstructive jaundice
What are gallstones made of? How are they diagnosed?
- Cholesterol, bile pigment stones
- HIDA scan (track flow of bile from liver to SI)
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