Exam 1 Flashcards
(163 cards)
1
Q
Use the 7-steps to systemically answer a drug information question.
A
- Secure demographics of requestor
- Obtain background information
- Determine and categorize the ultimate question
- Develop strategy and conduct search
- Perform evaluation, analysis, and synthesis
- Formulate and provide response
- Conduct follow-up and documentation
2
Q
7 steps to answer DI question: Secure demographics of requestor
A
Know your audience and how to effectively communicate
Medical jargon with pt vs physician
3
Q
7 steps to answer DI question: Obtain background information
A
Use gathered info form pt to determine effects of any other health problems etc that would need to be accommodated
4
Q
7 steps to answer DI question: Determine and categorize the ultimate question
A
Determine correct pt population affected and use appropriate resources
Pregnancy and lactation resources etc
5
Q
7 steps to answer DI question: Develop strategy and conduct search
A
Start with tertiary and follow lit hierarchy
EFFICIENCY
6
Q
7 steps to answer DI question: Perform evaluation, analysis, and synthesis
A
Use background info & consult other professionals to gain an objective view
7
Q
7 steps to answer DI question: Formulate and provide response
A
Determine best option, be aware of other options & present them with citations to the requestor
8
Q
7 steps to answer DI question: Conduct follow-up and documentation
A
Make sure correct person recieved info and keep as reference for later
9
Q
State and incorporate the 4-D’s of problem-solving into answering a question.
A
(define, design, do, debrief)
Define problem that needs solving
Design a plan to solve the problem
Do to plan
Debrief with an evidence-based recommendation
10
Q
Define and describe “evidence-based medicine (EBM)”.
A
Integration of best research with clinical expertise & patient values
11
Q
Describe a disease state practice guideline
A
“Directions” to diagnose and treat pts with a specific disease
&
Prepared by an expert panel coordinated by an organization or governing body
12
Q
“Directions” to diagnose and treat pts with a specific disease
A
Based upon the best evidence at a given time → guidelines do change over time due to new findings (results of primary lit)
13
Q
who is a part of the panel developing practice guidelines?
A
Panel with practitioners specialized in area of disease → usually involved with research for better understanding of disease and therapies
14
Q
how does the P/G panel rank evidence?
A
Panel searches lit for research evaluating new diagnostic techniques and/or therapies
Research evaluated to determine primary lit strengths and limitations
Research is graded (excellent to poor) by panel
P/G include recommendations with a grade of evidence level ( strong vs weak)
15
Q
study designs with one vs few vs many subjects
A
One: case report (unique occurrence or outcome in a single subject)
Few (approx 3-10): case series (unique outcome in a few similar subjects)
Many (more than 10): survey
16
Q
Yes surveys? can be…
A
cross sectional or retrospective
17
Q
retrospective w/ known outcome
A
purpose to determine CAUSE of outcome
—Subjects w/outcome vs subjects w/out outcome
CASE CONTROL!
—-Keys: quick method to “possibly” determine cause of outcome
18
Q
retrospective w/o known outcome
A
compare 2 or more groups; collect/analyze data/measure difference between groups
COHORT!
19
Q
case control
A
Keys: quick method to “possibly” determine cause of outcome
20
Q
cohort
A
Naturalistic study
Initial data then check back in a year to see changes etc
21
Q
no survey? Can be…
A
prospective
22
Q
prospective
A
Compare 2 or more groups and measure outcome
RANDOMIZATION (important for strength of evidence!!)
Everyone has equal opportunity to be in either group
23
Q
M: state whether fail to reject (Accept ) or reject Ho
A
Reject Ho when p < alpha
Accpet Ho when P > alpha
24
Q
N: state the type of error that can occur. What is the potential cause?
A
Error is POSSIBLE but doesn’t always occur
P < alpha → 1 < 2 → type 1 error possible
P > alpha → 2 > 1 → possible type 2 error
25
Type 1 error (alpha error)
1. Reject Ho when Ho should be accepted (false-pos)
2. One reason for type 1 error: CHANCE.
3. Saying theres a diff when there is no diff.
4. Probability of type 1 error = p-value x 100
26
Type 2 error (beta error)
1. Accepted Ho when Ho should be rejected (false-neg)
2. Saying there is no diff when there is
3. Two reasons for type 2 error: chance and/or small n
27
O: Define ‘randomization.’ (2 cards for O) (list purpose of randomization here)
Reduce bias
Try to make groups equal w/ demographics
To validate selected statistical tests
28
O continued: describe how study was Strengthened or Weakened by including or not randomization in study design
- All pts in study have equal opportunity to be in intervention or control
- Goal: study groups to be as equal as possible so that only diff b/w groups is one getting intervention vs control
- So, if a diff → attributed to intervention (cause/effect relationship)
29
P: State if primary endpt is subjective or objective
Subjective: pt can have influence on results
Objective: pt does not have influence on results
Very important for type of blinding done in the study
30
CCT *** PLZ KNOW ***
Best study design to measure and quantify differences in effect between 2 or more groups and cause and effect
Most robust study design to measure and quantify differences between an intervention and control group
Study is conducted to determine the outcome by the intervention
31
CCT process?
Population —> sample —> CCT —> conduct study using good methods —> results —> analysis via statistical tests —> interpretation —> formulate an evidence-based conclusion —> extrapolate to/apply within the population
32
R: Was the duration of clinical trial sufficient to answer objective?
Yes/no
33
BMP
Basic metabolic panel
-provides test, result, and reference interval
Na | Cl | BUN / glucose
K | HCO3- | Cr \
(Fish bone thing)
34
What is per-protocol (PP)?
- bad on own (RED FLAG!)
- Bias can be present
- Method of analyzing result from only pt who completed 100% of CCT.
35
T: How many pts did not complete the study? How do pts not completing the study affect the primary endpt results?
Evaluate number of and reasons for dropouts
| Throw out incomplete pts = bias
36
U: describe whether the primary endpt was clinically diff b/w intervention and control group. (2 cards)
- Every result needs to be evaluated in terms of diff present
- Not every study result that is statistically signif is clinically diff
- P-value says NOTHING abt magnitude of diff in outcome effect b/w intervention and control
37
U continued: p values and their significance in determining if clinically different
-Do not automatically conclude that all p alpha → not clinically diff
—No diff in outcome effect b/w intervention & control
-CAUTION
P > alpha does NOT mean results are equal, similar, or equivalent → accept Ho (NO DIFF STATEMENT)
38
randomized prospective Groups receive both “treatments?”
yes --> crossover
| no --> CCT
39
crossover
Pt serve as own control. Return to baseline (back where you started)
Typically used when testing bioequivalence
40
not randomized prospective
cohort
41
Locate reputable disease state practice guidelines using PubMed.
“Practice guideline” “insert disease state here” using MeSH (apparently…. Works without it too JS) but for the love don’t tell him if you used google or Samford Lib or the associations website.
42
strengths of disease state practice guidelines
Always updated with most recent findings….
| Relatively universal recommendations… aka you won’t look like a fool if you cite your source
43
limitations of P/G
only available for commonly studied diseases → no rare ones
not hard-set data; situational evaluations plus best judgement
44
Read and interpret disease state practice guidelines
Rank evidence rating from guideline to give informed recommendations
45
CCT ***PLZ KNOW WORD FOR WORD***
Best study design to measure and quantify differences in effect between 2 or more groups and cause and effect
46
CCT process?
Population —> sample —> CCT —> conduct study using good methods —> results —> analysis via statistical tests —> interpretation —> formulate an evidence-based conclusion —> extrapolate to/apply within the population
47
CCT peer review joural
Goal is to inc quality of published article/study
Manuscript sent to journal editor —> peers for review —> either rejected or tentatively accepted w/comments for author to improve/clarify
Manuscript may go back and forth for revisions until accepted/published (2-4 month process,hopefully completed within 9-12 months)
Signs it underwent peer review:
“Received (date), revised (date), and accepted (date)”
48
CCT trial registration
(clinicaltrials.gov)
All studies should be registered into this database so results of all projects are accounted
Reasoning: some researchers weren’t publishing “neg” trials (when pts were harmed)
Also to reduce publication bias
49
Funding for CCT
Gov, private orgs, foundations, and drug companies
Quality of study should be assessed regardless of funding source
BUT don’t assume a study is bias just bc of its sponsor (it’s too expensive to create a purposefully bias study, esp for drug companies)
50
Evaluating a CCT
CCT —> study objective/purpose —> primary endpoint —> primary endpoint “type” —> create null hypothesis for primary endpoint
sample —> randomization —> intervention vs control —> results —> endpoint result p vs alpha —> > > >
51
Primary endpoint
Outcome that is measured to determine if a difference exists between the intervention and control
Capable of answering the study question using proper measuring techniques and appropriate definitions
okay to have secondary endpts
52
secondary endpts
Should NOT be focus of study
Sometimes primary has p>alpha so investigators try to use secondary endpoints to convince reader that intervention is still good, but study is set up based on primary
53
Primary endpoint “type” subjective vs objective
Blinding type dec bias
Double blinding is best for Subjective
Objective can be open, single or double
Rule of thumb: double blind if possible
54
Primary endpoint “type” surrogate vs clinical
surrogate: Endpoint easily and quickly measured (LDL, weight, not always correlated to clinical outcome)
clinical: Ultimate outcome; major importance to pt (death, MI)
55
how to Create Ho for primary endpoint
There is…
No difference
Between (intervention) and (control)
In (measurable endpoint)
56
nominal data
yes/no
57
ordinal data
scale or ranking
58
continuous data
equal intervals
59
evaluate CCT: sample
Conduct a power analysis (at least 80%) to est appropriate sample size (n)
Difference is est between intervention and control (gamma rate)
Inclusion and exclusion criteria (all CCTs have this)
60
evaluate CCT: randomization
Keys: reduce bias, needed for stats to be valid, results in very similar groups
Intervention group and control group
61
evaluate CCT: results
Intention to treat (ITT) to include all pt results regardless of if they finished the CCT
Per-protocol (PP) results of only those finishing entire CCT are analyzed
Dropout rates should be similar between intervention and control groups
62
evaluate CCT: endpt results
Alpha always given at beginning of study before research begins
Can only use p-value for statistical purposes
Can’t say something is better by X%
63
V: Is the primary endpoint considered a surrogate or clinical endpoint? Briefly discuss the significance of endpoint type (Surrogate card)
Surrogate endpoints are NOT incorrect or inappropriate to measure in a study
Usually measured to quantify the degree of pharmacological effect produced by the intervention group
Endpoints used to correlate a clinical effect
DON’T GUARANTEE occurrence of a clinical event
64
V continued: Is the primary endpoint considered a surrogate or clinical endpoint? Briefly discuss the significance of endpoint type (clinical card)
Clinical endpoints are absolute outcomes that a pt can experience
Death, MI, renal failure, etc
65
W: Discuss the clinical usefulness of the primary endpoint results
Are results useful to be applied in practice?
66
X: Do the investigators adequately present in the Discussion section the key conclusions in an unbiased manner? Are these supported by the study results? Explain your response.
- Discussion section provides an interpretation of study results
- Usually includes comparison of results to similar studies
- Should include study limitations and how these could affect the study
- Can contain bias in terms of interpreting and applying results so watch out
67
Y: Identify the funding source for this study. Evaluate the significance of the funding source for the research project. Was it bias due to who the funds came from?
- Don’t automatically discredit a study due to the funding source (drug co)
- Evaluate entire study to determine strengths and limitations, not just where the funding source is
68
Z: is the clinical trial title misleading after reading the entire study? Explain.
Title should be an appropriate overview of study question
| Good study title is objective, clear, unbiased, and declarative
69
AA: briefly discuss the significance of study results (not just primary endpoint) and how well study applies to practice. Include to who these results can be extrapolated. “Tie together” all the study strengths and limitations and how these results can be used in practice (long list of 15 factors)
-Discuss how responses can be used collectively to formulate an overall critique of the CCT
Factors
- Study strengths/limitations
- Objective
- Endpoints
- Inappropriate control group used
- Interventions
- Sample size/power analysis
- How results/data is presented
- Measures of association calculations
- Selection bias, recall/reporting errors, ancillary therapy
- Conflict-of-interest
- Rationale for conducting the study
- Patient exclusion/inclusion criteria
- Dosing titration differences/wash-out period if needed
- Data collection methods
- Type I or II error possibilities
70
What is CONSORT and its purpose?
-consolidated standards of reporting trials
-established to improve the quality of reporting clinical trials in published lit
—Supported by an inc # of journals
-Other research types can report the investigation using the style of reporting a CCT
—Do not assume that all publications using this format are CCTs
71
Define publication bias
Suppression and/or failure to present data regarding negative study results
72
Define diagnostic
determine/confirm presence of disease
73
Define baseline
“normal” for pt --- often measured before drug therapy starts
74
Define monitor
“Assessment” --- determining efficacy and/or safety of therapy
75
Define direct pt PK parameters
adj of medications for individual pt
76
Define Specific drug levels
Determine toxic or subtherapeutic serum [ ]
77
Define reference range
- A statistically-derived numerical range obtained by testing a sample of healthy pt
- WNL = within normal limits
78
Define therapeutic range
Range of drug [ ] w/n which the probability of the desired clinical response is relatively high and the prob of toxicity is relatively low
79
Define critical value
- Result outside of ref range that indicates high risk of mortality
- Note: these values are set by policies in the lab and are usually flagged for review
80
BMP
Basic metabolic panel
| -provides test, result, and reference interval
81
Endpoint result p-value < alpha ---> yes?
Statistically significant/different —> reject null hypothesis —> possible for clinical difference —> assess difference in primary endpoint results between the 2 groups —> POSSIBLE type 1 error (chance is an option
82
Probability of type 1 error (alpha error):
Take p-value x100 to get % (% = probability of rejecting TRUE Ho)
This % also = probability that chance is reason for difference
This % is alsooooo probability of having type 1 error
83
Endpoint result p-value < alpha ---> no?
Not statistically significant/different —> accept Ho —> NO clinical difference —> POSSIBLE for type 2 error
Can’t use p value to determine probability of accepting false Ho, chance, or Small n for being reason for no difference or of having type 2 error
84
two reasons for type 2 error (beta error)
Chance
| Small n
85
relationship b/w power & n
Inc power by inc n which dec beta error possibility
86
power =
```
Power = 1 - beta
Power = ability to detect a difference in outcome between intervention and control if a difference truly exists
```
87
beta error should be < ___ %
20%
88
"landmark trial"
One CCT isn’t sufficient to adopt therapy as first choice to treat pts unless it’s a “landmark trial” which means you can apply it today
89
how CCTs are applied to practice
Usually combine results of multiple trials for evidence to incorporate newly developed therapy into practice/changing existing method of treatment
90
why are Both appropriately and poorly designed CCT published?
All CCTs may not translate into clinically useful info
Better quality if resulting from well-designed study
91
A: article citation
use AMA
92
B: state the type of study that best describes the investigation + how you determined it… also, discuss if it was appropriate to “answer” the study question
Uniform framework: always regardless of type
Primary study designs
93
uniform framework
Assignment: sample from pop assigned to group
Assessment: study is conducted with this sample and results collected
Analysis: results are analyzed
Interpretation: investigators interpret the results (what do these mean/tell us?)
Extrapolation: apply these results to the population
94
Format and content of CCTs
Title: indicate type of study design and purpose
Abstract: a brief overview of research; errors
Intro: research background; clinical trial objective
Methods: focus evaluating; study design/randomization, inclusion/exclusion criteria, setting, intervention/control, blinding, endpoints/outcomes, follow up procedure, sample size calculations and power analysis, any other analyses
Results: demographics of subjects, subject drop-outs/compliance, endpoints quantified, additional analyses, safety assessments
Discussion: interpret results, compare to other studies, generalizability, limitations
Acknowledgements: other contributors, FUNDING SOURCE, peer review dates/manuscript, acceptance date if applicable, registration
References/bibliography
95
CCT is primary study design to...
use as evidence to make decisions
96
CCT design
From population, sample pts randomized to intervention or control
Pts followed prospectively over time and outcome is measured
Difference in the outcome measure = assessed
Results used to make recommendations
97
cross-over
Study conducted to directly measure differences in outcome effect b/w groups
98
cross-over diff from CCT
study pts get both ‘therapies’
Need wash-out period between ‘therapies’ to pts return to BASELINE
Pts are own control… dec inter-pt variability
Need smaller sample size
99
cross-over design
From population, sample selected and randomized to intervention or control
Pts followed prospectively and outcome is measured
Pts stop ‘therapy’ and enter washout phase of the study
Pts are converted to the ‘other therapy’ and followed prospectively and outcome is measured again
Diff in outcome measure is assessed
100
case-control
Outcome is known → study conducted to determine etiology/reason for outcome
Study conducted to determine the cause of adverse event (like MI)
101
case-control design
From population, one group with outcome ID (case group); another group from population ID but without outcome (control)
Two groups of pts are as equal as can be with exception to case group having the outcome and controls do not
Pt data RETROSPECTIVELY reviewed to ID diff between case/control
Diff may be possible reason of adverse event
102
Cohort (prospective)
Gathers data ‘naturally’ from a group by following/monitoring pts without intervention
Two groups can be compared, but groups may not be similar so diff in outcomes may not be true
Conducted to determine an outcome without intervention
103
Cohort (prospective) design
Sample from population naturally taking the ‘intervention’ is selected along with a sample of pts naturally taking control…
Pts are followed prospectively over time and outcome is measured
A diff in the outcome measure is assessed
Major problem = two groups may not be equal and diff measured may be biased
104
Cohort (retrospective)
Gathers data ‘naturally’ from a group
Conducted to determine an outcome without intervention
Two groups can be compared, but groups may not be similar so diff in outcomes may not be true
105
Cohort (retrospective) design
Sample from population naturally taking the ‘intervention’ is selected along with a sample of pts naturally taking control…
Pts data/history are retrospectively reviewed to gather outcome info
A diff in the outcome measure is assessed
Major problem = two groups may not be equal and diff measured may be biased
106
cross-sectional
Survey
| Gathering data at one point in time
107
case report (Case series)
Occurrence of outcome in a single pt (small group)
Difficult to use as evidence
Could be by chance that outcome happened
108
C: state the QUESTION that is to be answered by conducting this study. Was the study purpose clearly stated?
Stated in the introduction section (usually last paragraph)
| Convert the study purpose/objective into a question
109
D: Briefly discuss the rationale for conducting this study. Do the investigators provide a discussion of how this study will be better designed to provide more definitive results and/or overcome prior study limitations? Is it another “me too” or “first of it’s kind” to answer a question?
Each study has a reason for being done
| Rationale is presented in the intro section
110
E: State the primary endpt (dependent variable). Was this appropriate and were precise methods used to measure it? Other ref may be needed to answer/
Each study will measure ONE outcome to use to answer the study question
Data gathered for primary outcome analyzed to…
- --Determine if diff exists b/w intervention and controls
- --Quantify the diff
inadequate/inappropriate outcome measurement techniques lead to poor study design and meaningless results
111
F: state the intervention groups and control groups. Is an appropriate intervention being compared to an appropriate control?
Every CCT has an intervention and a control
Outcome results of these groups are measured and compared to determine diff and quantify said diff.
“Magnitude of effect”
Placebo as control is appropriate for many studies est if researching to determine cause-and-effect
112
Compare effect of intervention to…
Est therapy to determine if intervention is better OR placebo to determine if intervention has any therapeutic effect
113
G: State the Ho (based upon primary end pt)
“There is NO DIFF b/w [intervention] and [control] in the [endpoint of measure]” → GENERIC STATEMENT
Statistical result is used to determine whether Ho should be rejected or ‘accepted’ (aka failed-to-be-rejected)
114
H: evaluate the pt inclusion/exclusion criteria. Were these appropriate for the study question? Selection bias? How do these affect the extrapolation to the pop?
Inclusion and exclusion criteria are important to know so the study results can be EXTRAPOLATED from study to pop
Excluding complex pts is typical to reduce variability in results from the groups
Usually excluded: preg, lactating, renal/liver failure
115
I: define “power” and the purpose of a power analysis. Was power analysis done? If so, was the calc and resulting % appropriate? Were appropriate variables included?
Power: ability of a study to detect the diff in outcome effect b/w intervention & control if there is a diff.
Minimum power = 80%
Alpha = 0.05
General principle: INC power by INC n which DEC beta-error (type 2)
- --Large diff in outcome effect require smaller n
- --Small diff in outcome effect require large n
Gamma = estimated diff in outcome effect b/w the intervention and control
Prior research is used to guestimate expected outcome
116
power analysis
a process to calculate an adequate # of pts to enroll into study so study is able to detect and quantify the diff in outcome effect between intervention and control
117
J: state the type of data that primary endpt is being presented and used in the calculation of p-value
Nominal: yes/no data, mutually exclusive
Ordinal: ranked/scale data
Continuous: data that have equal intervals
The data that has “an effect” on the statistical tests used and data presentation methods
118
K: state the actual results for the primary endpt plus p-value. Interpret p-value in terms of a probability. State the alpha value, is this value stated or assumed? Is an appropriate alpha value included?
All statistical analyses compute a p-value, which informs the researched whether result is statistically signif or not
Compare p-value to alpha-value
Setting alpha above 0.05 may lead to less robust study while above 0.05 leads to more stringent studies
A p-value says nothing about the magnitude of diff of the outcome effect b/w the intervention and control
119
P-value = probability value
P < 0.05 → statistically signif diff
| P > 0.05 → no statistically signif
120
L: state whether the primary endpt was or was not statistically signif
P < alpha = statistically signif → reject Ho
P > alpha → not statistically signif & inconclusive
121
Point of care testing
Dx testing performed at or near the site of pt care
122
adv of Point of care testing
reduced turn-around time, test portability, and pt self-testing
123
disadvantages of Point of care testing
misuse or misinterpretation of results, documentation errors, inappropriate disposal of testing material, and quality assurance issues
124
International Normalized Ratio (INR)
Normal ref range = 0.9 - 1.0
Used for efficacy and safety of warfarin
Therapeutic range for warfarin = 2.0-3.0 or 2.5-3.5 (depending on disease)
Used as dx tool (liver dysfx, malnutrition)
Standardized monitoring parameter recommended by american college of chest physicians
125
INR equation
= ( prothrombin sec of pt / prothrombin sec of control ) ^ ISI
ISI based on thromboplastin reagent used in each lot and reported in the package
***High potential for human error
126
Absolute neutrophil count (ANC)
Risk of infection is greatly inc w/ ANC less than 500/mm^3
| Commonly associated with chemotherapy agents/tx
127
ANC equation
WBC x (% neutrophils + % bands) / 100
128
CMP
Comprehensive metabolic panel
- Lists component, pt value, standard range, and units
- Same as BMP plus GFR, Ca, albumin, protein total, etc
129
Other acronyms/terms in lab value interpretations
- SMA-7: sequential multiple analyzer
- Chem-7, Chem-8
- Chem Profile 20
130
Most common timing of tests (4)
Hourly, daily, monthly, annually
131
Specimens usually tested in blood (venous or arterial) (2)
- Plasma = fluid, acellular portion of blood; Buffy layer (55%)
- Serum = liq that remains after the fibrin clot is removed from plasma
132
Specimens usually tested for excretion
Urine
| Stool
133
Other fluids tested besides blood and excretions (5)
- CSF
- wound drainage
- sputum
- tissues
- gastric secretions
134
Classifications of Lab Data: qualitative test
Not a specific amt (aka pos or neg)
135
Classifications of Lab Data: quantitative test
Reported as an exact numeric measurement
| -Abnormal lab in a normal pt is NOT always abnormal
136
Classifications of Lab Data: semi-quantitative
Reported w/ various degrees of neither pos nor neg w/o exact #
137
Sensitivity
- Ability of test to ID positive results in pts who actually have the disease (true positive rate)
- Also refers to range that can be accurately measured
138
Specificity
- Percent of negative results in people without the disease (true negative)
- The lower the specificity number, the higher chance of false positive (could be expensive if it leads to more tests/procedures)
139
What is included in a complete blood count (CBC)
RBCs, WBCs, Hgb, Hct, RBC indices, reticulocyte count, platelets/thrombocytes
140
CBC with differential
analysis of the cells of WBCs
WBCs and platelets are actual counts
HgB (#) and Hct (%) → based on volume and may be artificially high in pts with dehydration
141
Anion Gap (AG or “R”)
Blood and urine anion gap
Blood: associated with metabolic acid/base disorders
Urine: associated with diagnosis of renal tubular acidosis (RTA) types 1-4
Blood anion gap normal range 5-12
142
AG or R equation
Serum Na = R + [ (HCO3- + Cl-) ]
R = Na+ - (HCO3- + Cl- )
R=unmeasured acids (like lactate, phosphates, sulfates, and proteins which equals 5-12 in normal situations)
May be artificially low in pts with low albumin levels
Levels R>15 is metabolic acidosis
143
Correcting for albumin
Total Ca includes ionized and bound form of Ca
Total Ca (8.8-10.2 mg/dL)
Ionized Ca active form (4.5-5.6 mg/dL)
Need to correct for albumin levels less than 4 g/dL (hypoalbuminemia) for Ca and phenytoin
144
Corrected phenytoin equation
= pt lvl / [0.9 x (pt albumin/4.4) + 0.1 ]
145
Corrected Ca equation
= [(4-albumin) x 0.8] + measured serum Ca
146
Common calculations
```
Correcting for low albumin
Calcium
Phenytoin (Dilantin)
Anion gap
Absolute neutrophil count (ANC)
International normalized ratio (INR) (calculated for you)
```
147
Arterial blood gases (ABGs)
Must get history and physical exam
Draw ABGs and BMP simultaneously
BMP: HCO3-; 22-28 mEq/L (in fish bone structure bottom middle)
148
ABGs and normal ranges are..
```
pH: 7.35-7.45
pCO2: 35-45 mmHg
pO2: 80-100 mmHg
calculated HCO3: 22-26 mEq/L
O2% saturation: greater than 95%
```
149
Albumin
Normal albumin 3.5-5 g/dL
Synthesized in liver
Plasma osmotic P, binding and transportation of various hormones, anions, FAs, and drugs!!!
150
Albumin takes ~___ days to change in MOST situations
20 days!!
Takes ~8 days to see a 25% change in albumin after significant liver damage
151
Hepatic function markers
AST, ALT, alkaline phosphatase
Elevated AST and/or ALT suggest hepatocyte damage or hepatic inflammation (not indication for etiology or severity of liver dysfunction)
AST (aspartate aminotransferase): present in heart and other tissues; half life of 17 hrs
ALT (alanine aminotransferase): more specific for liver; half life of 47 hrs
152
Hepatic dysfunction
True liver failure is based on multiple factors
1. Child-Pugh Classification
2. Model end stage liver disease (Meld Score)
153
Child-Pugh Classification
Uses albumin, total bilirubin, prothrombin time or INR, ascites, encephalopathy
Used to ID classification in liver disease and adjust meds
There’s a chart to determine severity (slide 37 if interested)
154
Model end stage liver disease (Meld Score)
Uses SCr, total bilirubin, INR, and serum Na
| Used to ID liver transplant and severity of disease (diagnostic tool)
155
Renal function
Use Cockcroft and Gault to est CrCl
Don’t forget multiply female by 0.85
DO NOT use decimals clinically
Use ABW or IBW where appropriate
156
WBC differential
- must add to 100
- Neutrophils = most numerous WBCs (aka segs or polys)
(Chart pic looks like weird X)
WBC >Hbg (top) < Plt
HCT (bottom)
157
Causes of WBC elevation
-Neutrophilia: infection or inflammation
—Left shift: presence of immature neutrophils/”bands”
-Eosinophilia: parasitic infection or allergic response
-Basophilia: chronic inflammation
-Monocytosis: associated with recovery state of bacterial infection (TB)
-Lymphocytosis: viral infection or lymphoma
158
Sources of lab errors: pt factors
Age, gender, wt, diet, preg, chronic disease, incorrect pt history
159
Sources of lab errors: Improper handling of specimen
Using incorrect tude (INR)
| Hemolysis of blood sample (K)
160
Sources of lab errors: timing of lab draw
Issue if trying to do PK
161
Sources of lab errors: error with analysis
Use of incorrect reagents
| Mislabeling samples
162
Sources of lab errors: medications
False pos for opiates on UDS with mutli drugs (ranitidine, sertraline, naproxen, others)
163
Clinical pearls
Do not order lab tests unless it will be used in decision making
Be skeptical of unusual results → better to repeat a test than act on incorrect data
Treat pts NOT NUMBERS
