Cobas 8000 P1 Flashcards
1
Q
What are the analytical methods that are performed on the Cobas 8000 Module?
A
- spectrophotometry: endpoint
- spectrophotometry: kinetic
- turbidimetry tina-quant
- CEDIA
- KIMS
2
Q
What method is used for testing Na, K, and Cl?
A
ISE
3
Q
What tests are affected by hemolysis?
A
- AST
- Direct Bilirubin
- Phosphorus
- ALT
- Magnesium
- Potassium
- LDH
4
Q
What disease states may show hypercalcemia?
A
- Addison’s Disease & thyroid toxicosis
- hyperparathyroidism
- malignancy
5
Q
What disease states may show hyperphosphatemia?
A
- renal insufficiency (failure)
- hypocalcemia
- hypoparathyroidism
- tumor lysis syndrome
6
Q
What disease states may show hypocalcemia?
A
- tetany
- osteomalacia
7
Q
What disease states may show hypophosphatemia?
A
- rickets
- hypoparathyroidism
- Fanconi’s Syndrome
8
Q
What is the clinical utility of prealbumin?
A
- a sensitive indicator of change in nutritional status
- decreased during protein calorie malnutrition and liver disorders
9
Q
What is true about calcium?
A
- decreases neuromuscular excitability
- regulated by PTH
- has role in blood coagulation
- activates enzymes
10
Q
What disease produces elevated serum and/or urine amylase?
A
- pancreatitis
- other diseases include: inflamed salivary glands (mumps), stomach ulcers, cancer of the pancreas, gallstones, CF, nephritic syndrome
11
Q
What organ is ALT a sensitive diagnostic aid for?
A
- liver
when ALT levels are elevated, disease is usually hepatitis or cirrhosis
12
Q
If a CSF specimen was labeled as “bloody” and was obtained by a traumatic puncture, how would the protein results be affected? Why?
A
when RBCs are introduced into the fluid, so are proteins from the plasma fluid
plasma is component of blood which contains all proteins in body
13
Q
What is the clinical significance of rheumatoid factor testing?
A
important in diagnosis of rheumatoid arthritis and other inflammatory disorders
14
Q
What is “direct” or conjugated bilirubin?
A
the soluble form of bilirubin, made by the liver from breakdown of indirect bilirubin
15
Q
What is “indirect” or unconjugated bilirubin?
A
circulates in the bloodstream bound to albumin; insoluble in water
16
Q
How is indirect bilirubin calculated?
A
indirect bilirubin = total bilirubin - direct bilirubin
17
Q
What effect does light have on bilirubin?
A
light breaks down bilirubin
18
Q
What disease states could show an elevated bilirubin?
A
- hepatitis
- liver cancer
- blockage of bile ducts
- HDN
- hemolytic disorders
19
Q
What tests can be done on the Cobas 8000 Module to measure renal function?
A
- blood urea nitrogen (BUN)
- creatinine levels in serum
- BUN to Creatinine Ratio
- serum and urine osmolality
- uric acid (serum and urine)
20
Q
What disease states can be caused by a deficiency in Vitamin D (Ca, Mg)?
A
- neuromuscular and skeletal abnormalities
- rickets
- osteomalacia
21
Q
What conditions have shown an increased serum magnesium concentration?
A
- hemolytic anemia
- renal failure
- hypothyroidism
22
Q
What disease is commonly associated with an elevated uric acid level?
A
The crystals formed when uric acid is not properly filtered by the kidneys accumulate in the joints causing gout, necrosis, and chronic renal failure
23
Q
What are the main sources of LD enzymes?
A
- pancreas
- heart
- liver
- skeletal muscles
24
Q
What are possible reasons for an elevated LD value (in vivo or in vitro)?
A
- organ tissue damage
- subarachnoid hemorrhage
- cirrhosis
- ketoacidosis
- necrosis of liver
- hemolysis
25
What is the alternate name and source for SGOT?
- aspartate aminotransferase (AST)
- source: heart and liver
26
What is the alternate name and source for SGPT?
- alanine aminotransferase (ALT)
- source: liver
27
What conditions would cause an increased ALT and AST?
- acute hepatitis
- primary biliary cirrhosis
- metastatic hepatic carcinoma
- alcoholic cirrhosis
28
What condition gives the highest ALT and AST?
acute hepatitis
29
What is haptoglobin?
glycoproteins produced by the liver; powerful, free hemoglobin binding proteins
30
What is the clinical application of the haptoglobin test?
- in hemolytic anemias associated with the hemolysis of RBCs, the released hemoglobin is quickly bound to haptoglobin and the complex is quickly catabolized
- this results in a diminished amount of free haptoglobin in the serum
- this decrease cannot be quickly compensated for by normal liver production
- as a result, the patient demonstrates a transient, reduced level of haptoglobin in the serum
- this test is useful in the detection of intravascular hemolysis
31
What are the two main sources of CK?
- CK-MM, CK-MB
- skeletal, cardiac muscle, and brain
32
What disease are CK Determinations chiefly useful in diagnosing?
heart attacks, myocardial infarctions
33
What enzyme shows an elevation first following a myocardial infarction resulting in heart damage? How soon after the infarct would the rise be apparent?
- myoglobin rises 1-2 hours after onset of symptoms
- CK-MB rises within 2-6 hours and peaks around 12-24 hours
34
What disease shows grossly elevated CK results?
muscular dystrophy
35
What are the sources of alkaline phosphatase?
bone and liver
| can also be found in placenta
36
What alkaline phosphatase is heat labile?
bone
37
What conditions show a high liver alkaline phosphatase?
- cholestasis
- cholecystitis
- cholangitis
- cirrhosis
- hepatitis
- fatty liver
- sarcoidosis
- liver tumor
- liver metastases
- drug intoxication
38
What conditions would have a high bone alkaline phosphatase?
- Paget's Disease
- osteosarcoma
- bone metastases of prostate cancer (high/very high ALP)
- renal osteodystrophy
- fractured bone
39
What is the primary source of ALP when ALP is elevated and GGT is normal?
likely of bone or placental origin
40
What should you do if both ALP and GGT are proportionately elevated?
investigate the biliary tree
- if the tree is negative for general or focal dilation, ALP/GGTP elevation may be cholestatic or due to an "infiltrative process"
41
What does it mean if GGT is solely elevated or discordantly higher than ALP?
- there may be an "induction elevation" of GGT (as with alcohol or medications)... which could be superimposed on some microscopic ductal problems
- so, liver biopsy would seek to rule out any canalicular or ductular cholestasis or ductular injury/inflammation
42
What enzyme is usually tested when looking for signs of liver disease?
GGTP
43
What types of liver disease are associated with an increase in GGTP?
- cirrhosis
- liver cancer
- hepatitis
44
What is the preferred specimen for the Iron-TIBC Test? Why?
- serum represents the concentration of iron and its transport protein transferrin
- EDTA and oxalate plasma can cause decreased results, due to chelating of the bound iron
45
How do you treat a 4+ lipemic specimen before running it?
- repeat the Na on AVL instrument using direct ISE principle
- Roche's ISE method is based on the delusional ISE principle
46
What is the chemical reaction for LD?
lactate + NAD+ + H+ --> LD --> pyruvate + NADH
47
What is the reaction for the creatinine methodology on the Cobas 8000 702 Module?
- method is based on the conversion of creatinine with the aid of creatininase, creatinase, and sarcosine oxidase to glycine, formaldehyde and hydrogen peroxide
- catalyzed by peroxidase, the liberated hydrogen peroxide reacts with 4-aminophenazone and HTIB to form a quinone imine chromagen
- the color intensity of the quinone imine chromagen formed is directly proportional to the creatinine concentration in the reaction mixture
48
What is the chemical reaction for Fe on the Cobas 8000 502 Module?
- under acidic conditions, iron is liberated from transferrin
- lipemic samples are clarified by the detergent
- ascorbate reduces the released Fe3+ ions to Fe2+ ions which then react with FerroZine to form a colored complex
- the color intensity is directly proportional to the iron concentration and can be measured photometrically
49
How is globulin calculated?
globulin = total protein - albumin
50
What is A/G Ratio?
Albumin to Globulin Ratio
51
How is direct bilirubin derived on the Cobas 8000 502 Module?
- nitrous acid in combination with sulfanilic acid forms a diazonium salt
- this diazonized sulfanilic acid reacts with bilirubin to form isomers of azobilirubin
- only conjugated bilirubin is converted by the diazonized sulfnailic acid
- produces a red color and is measured photometrically, directly proportional to the direct (conjugated) bilirubin concentration
52
Why must analyses of glucose measured in serum, heparinized plasma, and capillary specimens be made as soon as possible?
- as the blood sits in the tubes, glycolysis (breakdown of glucose) is still occurring in the blood specimens
- performing the analysis as soon as possible allows for more accurate results before the glucose is depleted in the specimen
53
What is the preferred anticoagulant for glucose analysis? What purpose does the anticoagulant
serve?
- sodium fluoride
- inhibits glycolysis from occurring in RBCs giving a more accurate glucose result
54
Where should the glucose level in normal peritoneal fluid be?
same as the plasma glucose
55
Where should the glucose level in normal CSF be?
2/3 of the plasma glucose
56
What is the anion gap?
the interval between anions and cations (having to do with acid/base relationship in the body)
57
What are the two ways the anion gap can be calculated?
- (Na+ + K+) - (Cl- + HCO3-)
- Na+ - Cl- - CO2
58
What is the normal reference range for anion gap?
8-16 mol/L
59
What is the most common clinical cause of decreased anion gap?
metabolic alkalosis
60
What is the most common clinical cause for increased anion gap?
presence of positively charged ions such as in metabolic acidosis, increase in acidity due to metabolic processes
61
What is the clinical significance of increased homocysteine?
cardiovascular disease
62
What are some possible conditions associated with pre-renal hyperuricemia?
- poor perfusion
- cardiac decompensation
63
What are some possible conditions associated with renal hyperuricemia?
- tubular necrosis
- increased protein
64
What are some possible conditions associated with post-renal hyperuricemia?
- obstruction
- obstruction of urinary flow
65
What happens to the BUN/Creat Ratio when prerenal causes are suspected?
BUN/Creat >>20:1
66
What happens to the BUN/Creat Ratio when postrenal causes or obstruction are suspected?
BUN/Creat << 20:1
67
Which organ is most affected by very low glucose levels in the blood?
brain
68
What effect does insulin have on blood sugar levels? What type of diabetes mellitus is insulin dependent?
- decreases blood glucose levels
- Type 1
69
What is the most common disease associated with an elevated blood sugar level due to impaired carbohydrate metabolism?
diabetes mellitus
70
What hormones help regulate blood glucose concentration?
- increases glucose: glucagon, ACTH, growth hormone, cortisol, T3 and T4, epinephrine
- decreases glucose: insulin
71
How can uncontrolled diabetes lead to ketosis and possible diabetic coma?
- when lacking the ability to break down glucose, the body looks for alternative sources such as breaking down fatty acids, which ketones are the byproducts of this metabolism
- this is usually a result of uncontrolled diabetes, not giving the proper amount of insulin to break down glucose for energy, leading to alarming levels of glucose
- presence of ketones leads to acidic conditions in the body throwing off electrolyte balances, leading to starvation of the brain (coma)
72
What disease states can a GTT help diagnose?
- diagnoses the patient's ability to metabolize glucose (ability of insulin to break down glucose)
- test can help detect diabetes mellitus, gestational diabetes
73
Why are patients schedule for GTT instructed to eat a diet heavy in carbohydrates for 72 hours prior to the test?
overload of carbohydrates causes an increase in blood glucose levels
| blood glucose will still be increased if patient has issue with insulin
74
What are the two functions of chloride in the body's physiology?
- maintains osmotic pressure (hydration)
- acid/base balance
75
What would show a decrease in serum CO2 content?
hyperventiliation
76
If a hemolyzed sample for electrolyte determination comes into the laboratory, is the specimen acceptable? Why? Which results are more affected by hemolysis?
- no
- will give increased potassium results
- lysing of the RBCs causes a release of intracellular potassium
77
What disease has an elevated serum acid phosphatase?
prostate cancer
78
What is the optimal pH for acid phosphatase activity?
5.0
79
If a specimen for serum acid phosphatase must be stored before the determination is made, how is the optimal pH achieved and maintained?
frozen to stabilize the enzyme once the pH is obtained
80
What organ has pseudocholinesterase?
liver
81
What is a reason for performing the pseudocholinesterase test?
if a patient is lacking the enzyme pseudocholinesterase, they are unable to break down succinylcholine, a respiratory relaxer causing prolonged paralysis
82
What enzyme other than amylase can be measured to determine pancreatic function?
lipase
| more specific, peaks later, lasts longer than amylase
83
What is the clinical significance of C-reactive protein?
indication of inflammation in the body, also bacterial infection
84
What is the clinical significance of HS-CRP?
determines the risk of heart or vascular disease
85
How does amylase and lipase differ relative to the duration the enzyme levels remain elevated in pancreatitis?
- lipase: peaks after amylase, lasts longer giving better indication for late detections of acute pancreatitis
- amylase: peaks before lipase and falls before lipase
86
What are the specimen requirements for a fasting lipid profile? What is an indication that the patient has not been fasting?
- patient must be fasting
- lipemic serum; caused by triglycerides
87
What is the Friederwald Formula? What circumstances would make the formula inaccurate and unusuable?
- LDL = total cholesterol - HDL - (triglycerides/5); measurement of LDL cholesterol levels (direct)
- only accurate if triglycerides are less than 400 mg/L
88
What is a chylomicron?
contains mainly triglycerides, with cholesterol and small amounts of phospholipids (free lipids) causing a lipemic specimen
| normal fasting patient has none present
89
What is HDL?
high density lipoproteins
- transports cholesterol out of the cells
90
What is LDL?
low density lipoproteins
- transports cholesterol into cells
91
What is VLDL?
transports endogenous triglycerides
92
What is Apolipoprotein A1?
major protein constituent of HDL
93
What is Apolipoprotein B?
major protein constituent of LDL
94
What are the clinical applications of Apolipoprotein A1 and Apolipoprotein B Testing?
- apolipoprotein concentrations provide sensitive and specific markers for coronary artery disease
- measurements of Apo A1 and B are useful tools for the assessment of CAD
- Apo A1 has questionable clinical utility
- Apo B may be important in the genesis of atherosclerosis
- high levels indicate increased risk for cardiovascular disease
95
How is iron absorbed into your system?
- food is introduced into the stomach which when the iron Fe+ meets the low pH, it is reduced to Fe2+ (aided by Vitamin C) enters the mucosal walls of the intestine
- Fe2+ are bound to transport proteins, oxidized by the ceruloplasmin to Fe3+ and bound to transferrin, entering the plasma
96
How do you calculate the percent saturation?
percent saturation = [iron/(UIBC + iron)] *100
97
What are the physiological functions of iron and transferrin?
- iron: important in uptake of oxygen in RBCs
- transferrin: transport protein of iron
98
What are the normal ranges for iron and TIBC?
- iron: 60-170 ng/mL
- TIBC: 250-450 ng/mL
99
What conditions are associated with decreased iron values?
- iron deficiency anemia
- anemia of inefficient hemoglobin synthesis
100
What conditions are associated with increased iron values?
- iron hemochromatosis
- sideroblastic anemia
101
What is ASO (anti-streptolysin O antibody)?
indicates that a streptococcus infection or poststreptococcal sequelae are present
102
What are the clinical applications of ASO?
- increased ASO levels are observed in approximately 85% of the cases of rheumatic fever or pharyngitis associated with ground A b-hemolytic streptococcal infection
- ASO titers rise as early as 1 week post onset and peak at 3-5 weeks
- values typically return to normal levels within 6-12 months
103
How does Cystatin C measure a patient's glomerular filtration rate?
- Cystatin C is produced by all nucleated cells at a constant rate and the production rate in humans is remarkably constant over the entire lifetime
- elimination from this circulation is almost entirely via glomerular filtration
- for this reason, the serum concentration of Cystatin C is independent from muscle mass and gender in the age range 1 to 50 years
104
What are the advantages of testing Cystatin C over serum creatinine?
serum creatinine is the most commonly used marker for estimation of GFR but it is significantly changed by other factors such as muscle mass, diet, gender, age, and tubular secretion
105
What are some inflammatory and infectious disease that can cause a decrease in C4 levels?
- systemic lupus erythematosus
- rheumatoid arthritis
- subacute bacterial endocarditis
- viremia
- parasitic infections
- bacterial sepsis
106
What are the two pathways of the complement system?
- classical
- alternative
107
What complement factor is common to both the classical and alternative pathways?
complement factor C3
108
Why do we measure C3?
the concentration of C3 and its degradation products can be evaluated as a parameter for activation of the complement system
109
Why is it important to measure a1-antitrypsin?
is an important, positive acute phase reactant found in elevated concentrations in inflammatory processes, tissue necrosis, malignancy, and traumas
110
What compounds can albumin bind and solubilize?
- bilirubin
- calcium
- long chain fatty acids
- toxic heavy metal ions
- pharmaceuticals
111
What disease type do elevated serum levels of beta2-microgloboulin indicate?
renal diseases such as glomerulopathies, tubulopathies, renal failure, amyloidosis
112
What are the two main functions of ceruloplasmin?
- transports copper
- has a catalytic function in the oxidation of iron, polyamines, catecholamines, and polyphenols
113
What are the differences between how we measure serum protein and urine protein?
- serum protein is measured by using the test total protein
- urine protein is measured by using the test TPUC
114
Where are plasma proteins synthesized?
liver, bone marrow, plasma cells, spleen, lymph nodes
115
What is the test method used for total protein?
colorimetric
116
What are cerebrospinal fluid protein measurements used for?
CSF protein measurements are used in the diagnosis and treatment of meningitis, brain tumors, and infections of the central nervous system
117
What is the correlation between serum HDL levels and the risk of atherosclerotic disease?
- monitoring of HDL cholesterol in serum is of clinical importance since an inverse correlation exists between serum HDL cholesterol concentrations and risk of atherosclerotic disease
- elevated HDL levels are protective against coronary heart disease
- low levels of HDL increase cardiovascular risk
118
How does ISE measure the analytes: Na, K, and Cl?
- ISE is based on the measurement of a potential that develops across a selective membrane
- the response of the electrochemical cell is therefore based on an interaction between the membrane and the analyte that alters the potential across the membrane
- the selectivity of the potential response to an analyte depends on the specificity of the membrane interaction for the analyte
119
What is amikacin?
a semi-synthetic aminoglycoside that exhibits bactericidal activity against a wide range of pathogens, including many organisms resistant to other aminoglycosides
120
Why is amikacin measured?
- is active in vitro against gram-negative organisms, penicillinase and non-penicillinase producing staphylococci
- strength of drug is due primarily to its high degree of resistance to aminoglycoside-inactivating enzymes
- determination of serum or plasma drug levels is required to achieve optimum therapeutic efficacy and minimize toxicity
121
What are the normal reference ranges for Na, K, Cl, CO2, glucose, Ca, BUN, and creatinine?
- Na: 136-145 nmol/L
- K: 3.5-5.1 nmol/L
- Cl: 98-107 nmol/L
- CO2: 22-33 nmol/L
- glucose: 74-100 mg/dL
- Ca: 8.4-10.5 mg/dL
- BUN: 6-20 mg/dL
- creatinine: 0.8-1.2 mg/dL
122
What test results are affected if the lavender top tube was collected before the gold by the phlebotomists? How are the results affected?
- increased: K
- decreased: Ca, Fe, Mg, Zn
- ALKP and other enzymes would show spurious results
