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103 Cards in this Set
- Front
- Back
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What is the difference between plasma and serum?
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Plasma contains clotting factors and fibrinogen, serum does not contain fibrinogen or clotting factors because they were used during the process of forming a blood clot.
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What is the normal range for fasting serum glucose?
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70-105 mg/dL
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What are the critical values for a fasting serum glucose?
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<50 and >400 mg/dL
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What is the most common cause of hypoglycemia?
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Overdose of insulin
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What is uremia?
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Condition of abnormally high urea nitrogen
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What is azotemia?
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Significant increase in plasma concentrations of urea and creatinine in kidney insufficiency
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What is pre-renal azotemia?
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Result of poor perfusion of kidneys; low GFR. Seen in dehydration, shock, CHF, low blood volume, fever, stress, severe burns
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What is renal azotemia?
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Diminished GFR from acute or chronic renal failure. Seen with acute glomerulonephritis (GN), chronic GN, polycystic kidneys, nephrosclerosis
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What is post renal azotemia?
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Usually result of obstruction like kidney stones, enlarged prostate, tumors
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What is the main cause of an elevated BUN?
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Renal disease (renal failure, glomerulonephritis, pyelonephritis, acute tubular necrosis). Other causes: urinary obstruction, dehyration, shock, infection, DM
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What test is sensitive for the breakdown of creatinine muscle metabolism?
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Creatinine clearance
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What is a sensitive and specific screen for renal function?
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BUN + creatinine
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What is creatinine clearance?
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A measure of GFR. This test is also used to evaluate renal function in patients with wasting and to monitor the progression of renal disease.
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What is the best overall index of kidney function?
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Glomerular filtration rate (GFR)
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What causes gout?
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Uric acid which is insoluble in body fluids. It precipitates out in joints, often big toe and results in pain, inflammation and tissue damage. Can also cause renal stones.
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What disease is caused by an increase in uric acid?
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Gout
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What is multiple myeloma?
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Malignant proliferation of plasma cells - leads to marked increase in IgG - *monoclonal gammopathy* Protein leeches out Ca++ from bone -> osteoporosis, especially long bones and skull. Patient presents with pathalogic fractures
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What are some characteristics of Multiple myeloma?
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Elevated total protein, viscous blood, elevated BUN, creat, uric acid. *serum protein electrophoresis usually shows elevated IgG. Liver problems. *Alk phos during treatment leads to new bone bein laid down. * Bence-jones protein in 24 hour urine test.
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What is a good sign in treatment of multiple myeloma?
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Alkaline phosphate during treatment leading to new bone being laid down.
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What antibody is elevated in Multiple Myeloma?
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IgG
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What is the disease process that involves a malignant proliferation of plasma cells that leads to a marked increase of IgG?
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Multiple myeloma.
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What protein would you see in a 24 hour urine specimen of a patient with multiple myeloma?
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Bence-Jones protein
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How should you test for cardiac markers?
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Serial sampling/testing. Recommended on presentation, at 6-9 hours and at 12-24 hours.
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What are three major cardiac markers?
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Troponins-preferred marker of choice for sensitivity and specificity, Creatine kinase-MB (CK-MB), Myoglobin
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What other things should be considered when doing a cardiac workup along with the lab tests?
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Patient history, PE, risk factors and standards of care
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What are the normal values for Creatine Phosphokinase (CK=CPK) for men and for women?
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Men: 55-170 U/L, Women: 30-135 U/L
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What is the source of creatine phosphokinase (CK)?
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Found predominantly in heart, skeletal muscle, brain. Levels are elevated when injury occurs to these muscles or nerve cells
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What are the three isoenzymes of CK?
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CK-MB (heart), CK-MM (skeletal muscle), CK-BB (brain)
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What is the CK isoenzyme that relates to the heart?
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CK-MB
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What is CK-MB?
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It is an isoenzyme of CK. It is most specific for myocardial cells (but is also found in smooth muscle, bone and brain)
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What CK-MB result is highly suggestive of myocardial injury?
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3.0 ng/mL with a relative index of greater than or equal to 2.5
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What CK-MB result is indeterminate for myocardial injury?
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>3.0 ng/mL with a relative index of <2.5
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What are the normal values of myoglobin for men and for women?
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Men: 30-90 ng/dL. Women: <50 ng/dL
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What is myoglobin?
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Heme-containing, oxygen binding protein found in cardiac and skeletal muscle. Provides an early index of damage to the myocardium in acute MI or reinfarction.
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When is myoglobin released?
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As early as 1-3 hours post-injury; stays elevated for about 12 hours. Can be used to rule out diagnosis in the 2-6 hour period after onset of symptoms. More sensitive than CK but not as cardiac specific.
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What things besides an MI can cause an elevation of myoglobin?
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Trauma, renal disease, inflammation or ischemic changes to non-cardiac skeletal muscles
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What is the benefit of testing for myoglobin vs CK-MB?
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It may become elevated earlier in some patients. Can also be measured in urine and should be monitored in patients with MI since it is nephrotoxic.
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What kinds of troponin are tested as cardiac markers?
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Troponin T and Troponin I
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What are the normal values for cardiac troponin T and cardiac troponin I?
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Troponin T: <0.2 ng/mL, Troponin I: < 0.03 ng/mL
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What are troponins?
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Complex of 3 contractile proteins found in skeletal and cardiac muscle that regulate calcium-dependent interaction of myosin with actin for the muscle contraction apperatus
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What does the presence of troponin in the blood usually indicative of?
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Some type of myocardial injury
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How long do troponins remain elevated in blood after MI?
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4-10 days. Good for late-presenting patients
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What are the guidelines for diagnosis of acute MI?
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Characteristic rise and gradual fall of troponin OR CK-MB. At at least one of the followng: ischemic symptoms, pathologic Q waves on ECG, Changes on ECG indicative of ischemia (i.e. ST-elevation or depression), history of coronary artery intervention
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What cardiac marker rises in 4-8 hours, peaks at 12-24 hours and returns to normal 72-96 hours?
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CK-MB
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What cardiac marker rises in 2-4 hours, peaks at 8-10 hours and returns to normal in 24 hours?
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Myoglobin
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What 2 cardiac markers rises in 4-6 hours, peaks at 12 hours and returns to normal in 3-10 days?
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Troponin I and Troponin T
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What cardiac marker rises in 2-5 days and returns to normal in 10 days?
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LDH
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What tests are included in a liver function test?
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Bilirubin -( total, direct, indirect), Alanine Transaminase (ALT/SGPT), Aspartate Transaminase (AST/SGOT), Alkaline Phosphatase, Lactate Dehydrogenase (LDH), Gamma glutamyl transferase (GGT)
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What are the 3 forms of bilirubin?
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Unconjugated (indirect), Conjugated (direct), Total bilirubin
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What is unconjugated bilirubin (indirect)?
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Bilirubin bound to albumin, Water insoluble. Elevated levels can precipitate out in tissues.
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What is conjugated bilirubin (direct bilirubin)?
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Conjugated with glucuronic acid in liver. Water-soluble. Excreted in bile to intestines where there is bacterial activation and breakdown and then is excreted in feces and urine via the kidney as urobilinogen.
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What is total bilirubin?
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Sum of conjugated and unconjugated bilirubin.
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What are the 3 types of jaundice?
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Pre-hepatic/hemolytic jaundice, liver disease/hepatocellular jaundice, post hepatic/obstructive jaundice.
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What causes pre-hepatic/hemolytic jaundice?
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Hemolysis -> increase in indirect bilirubin (unconjugated). Disease states: hemolytic anemia, hemolytic disease of the newborn, transfusion reaction.
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What is kernicterus?
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In hemolytic disease of the newborn, bilirubin can crystallize out in brain and do brain damage. If bilirubin levels reach 18-20 mg/dL in newborn, exchange transfusion needed.
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What causes liver disease/hepatocellular jaundice?
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Injury or disease of parenchymal cells of liver. Inability to conjugate bili-> increased total bili, increased indirect and variable direct bili. Can be caused by viral hepatitis, cirrhosis, mono, or drugs.
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What is post-hepatic/obstructive jaundice?
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Obstruction of common duct or hepatic duct. Increased indirect, increased direct and increased total bili. Can be caused by gall stones.
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What 3 things can cause elevated conjugated (direct) bilirubin?
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Gallstones, extrahepatic duct obstruction (tumor, inflammation, gallstone, scarring), liver metastases
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What 5 things can cause elevated unconjugated (indirect) bilirubin?
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Hemolytic disease of the newborn, hemolytic anemia, hepatitis, neonatal hyperbilirubinemia, transfusion reaction
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What is the source of aspartate transaminase (AST/SGOT)?
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Heart, liver, skeletal muscle
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At what intervals does Aspartate transaminase (AST/SGOT) rise, peak and return to normal following disease or injury?
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Rises within 8 hours, peaks at 24-36 hours, returns to normal in 3-7 days
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Generally speaking, is ALT or AST more specific to the liver?
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Usually see a greater increase in ALT than AST as a result of inflammation. Exception: alcoholic hepatitis
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What is the relationship between alcoholic hepatitis ALT and AST?
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In alcohol related liver disease AST is usually more elevated than ALT (typically more than twice as high).
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What is usually indicated by sever elevations of ALT and AST (>1000)?
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INfection, toxins or shock to the liver
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What is the ratio of AST/ALT (aka DeRitis ratio) is what in patients with alcoholic cirrhosis, liver congestion and metastatic tumors of the liver?
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Greater than 1.0
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What is the AST/ALT ratio usually in patients with acute hepatitis, viral hepatitis and infectious mono?
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Less than 1.0
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What are the sources of Alanine Transaminase (ALT/SGPT)?
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Liver **, lesser amounts in heart, skeletal muscle and kidney
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In acute extrahepatic biliary obstruction, what liver enzyme is usually increased?
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ALT more than AST
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Of AST and ALT, which is more spcific for liver disease and which one is more sensitive to alcoholic liver disease?
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ALT more specific for liver disease. AST more sensitive to alcoholic liver disease.
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What is the source of Alkaline Phosphatase (ALP)?
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Mainly found in bone, liver and placenta (important in laying down bone in osteogenesis). Some kidney, intestinal walls and lactating mammary glands.
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What is the source of lactate dehydrogenase (LDH)?
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Heart, liver, RBC; some in skeletal muscle, kidney, brain, lung
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What are 5 isoenzymes of LDH?
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LDH-1: mostly from heart, LDH-2, mostly from reticuloendothelial system, LDH-3: lungs and other tissues, LDH-4: kidney, placenta, pancreas, LDH-5: liver and striated muscle
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What LDH isoenzyme makes up the greatest percentage of total LDH?
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LDH-2 (reticuloendothelial system) - 27-37%
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What is relevant of LDH-1 and LDH-2 and a myocardial infarction?
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their ratio "flips" Normally LDH-2 is greater than LDH-1, but in an MI, LDH-1 is greater than LDH-2.
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What is the source of amylase?
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Saliva, salivary glands, pancreas (from acinar cells); low levels in ovaries and skeletal muscle
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What is the main cause of elevated amylase?
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Acute pancreatitis (but lipase is more specific)
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What is the source of lipase?
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Pancreas
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What happens to the level of lipase in mumps?
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It is usually normal
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What are the electrolytes?
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Sodium, Potassium, Chloride, Bicarbonate
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What is a cation and an anion?
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Cation: positive charge, Anion: negative charge. **Positive charges must equal negative charges
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What is the normal reference range for sodium? Critical values?
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Normal: 135-145 mmol/L, critical: <120 or >160 mmol/L
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What is the significance of sodium?
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Major extracellular cation
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What is the normal reference range for potassium? Critical values?
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Normal: 3.5-5 mmol/L. Critical: <2.5 or >6.5 mmol/L
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What is one of the main functions of potassium?
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Acid-base balance - can't interpret K without knowing the acid/base status of the patient
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What is the most common cause of decreased potassium?
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Gastrointestinal loss
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What ist he normal reference range for chloride? Critical values?
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Normal: 98-106 mmol/L, Critical: <80 or >115 mmol/L
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What is the normal reference range for CO2?
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23-30 mmol/L
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What is the major roll of bicarbonate in serum (HCO3)?
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Acid-base balance
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What regulates the amount of HCO3?
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Kidney
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What is the normal reference range for bicarbonate (HCO3)?
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21-28 mEq/L
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What is an anion gap?
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Calulated: NA + K = Cl + HCO3 + 12. If the amount of Na + K is greater than the other half of the equasion by 25, an anion gap exists.
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What is bicarbonate actually?
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Venous CO2 value
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What are causes of an increased anion gap?
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Diabetic ketoacidosis, poisoning by ethylene glycol, salicylates, methanol, propyl alcohol, drug overdoes, lactic acidosis, alcoholic ketoacidosis, starvation, renal failure, ketogenic diets
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What is the normal value of total calcium and ionized calcium?
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Total: 8.8-10.5 mg/dL, ionized: 1.05-1.33 mmol/L
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What forms are calcium in?
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Approx 50% Ca++ is in the ionized form - physiologically active. The other 50% bound to albumin
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How does albumin level affect Ca level?
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50% of calcium is bound to albumin. Serum Ca level decreased by about 0.8 for every 1 gram decrease in serum albumin.
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How is ionized calcium affected by albumin level?
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It is not affected. Only non-ionized Ca is bound to albumin
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What is the calcium level we measure in blood?
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Total calcium
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What is the main cause of elevated calcium?
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Cancer. Especially with metastatic bone disease, multiple myeloma, non-endocrine tumors that produce PTH like substances (lung, breast, renal), Hodgkins disease.
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What is the most common cause of elevated blood phosphate levels?
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Kidney dysfunction and uremia
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What is the lipid calculation (Friedwald Formula)?
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LDL cholesterol = Total cholesterol - HDL cholesterol - (triglycerides/5)
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What is TSH (thyroid stimulating hormone) used for?
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It is the best test for diagnosing hyperthyroidism
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What is the best single test to diagnose and monitor hypothyroidism thyroid replacement?
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TSH (thyroid stimulating hormone) Differentiates primary from secondary hypothyroidism
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