1. Laboratory Test Utilization: The Good, the Bad and the Overused Tim Hamill, MD Director, UCSF Clinical Laboratories Tim Hamill, MD Director, UCSF Clinical Laboratories

2. The Good, The Bad & The Ugly A ‘Good’ test:A ‘Good’ test: Provides information that is useful in patient management decisionsProvides information that is useful in patient management decisions Screening: High sensitivity & NPVScreening: High sensitivity & NPV Diagnosis: High specificity & PPVDiagnosis: High specificity & PPV A ‘Bad’ test:A ‘Bad’ test: Uses resources but fails to provide information useful in patient management decisionsUses resources but fails to provide information useful in patient management decisions The ‘Ugly’ test:The ‘Ugly’ test: Uses resources and provides information that is misleading or irrelevantUses resources and provides information that is misleading or irrelevant A ‘Good’ test:A ‘Good’ test: Provides information that is useful in patient management decisionsProvides information that is useful in patient management decisions Screening: High sensitivity & NPVScreening: High sensitivity & NPV Diagnosis: High specificity & PPVDiagnosis: High specificity & PPV A ‘Bad’ test:A ‘Bad’ test: Uses resources but fails to provide information useful in patient management decisionsUses resources but fails to provide information useful in patient management decisions The ‘Ugly’ test:The ‘Ugly’ test: Uses resources and provides information that is misleading or irrelevantUses resources and provides information that is misleading or irrelevant

3. UCSF Test Utilization In 2009 UCSF performed an average of 486,000 tests per monthIn 2009 UCSF performed an average of 486,000 tests per month Annual test volume 5.8MAnnual test volume 5.8M Inpatient tests : Outpatient tests = 1:1Inpatient tests : Outpatient tests = 1:1 Inpatients: 15 tests/dayInpatients: 15 tests/day Outpatients: 4 tests per visitOutpatients: 4 tests per visit Stat : Routine = 1:3 overall (1:1 inpatient)Stat : Routine = 1:3 overall (1:1 inpatient) In 2009 UCSF performed an average of 486,000 tests per monthIn 2009 UCSF performed an average of 486,000 tests per month Annual test volume 5.8MAnnual test volume 5.8M Inpatient tests : Outpatient tests = 1:1Inpatient tests : Outpatient tests = 1:1 Inpatients: 15 tests/dayInpatients: 15 tests/day Outpatients: 4 tests per visitOutpatients: 4 tests per visit Stat : Routine = 1:3 overall (1:1 inpatient)Stat : Routine = 1:3 overall (1:1 inpatient)

4. UHC Comparison Data UCSF Ranks #1 in Tests Used per Patient Discharged

5. Causes of Test Overutilization* Ordering test panels rather than ala carte’Ordering test panels rather than ala carte’ Ordering tests as groupsOrdering tests as groups Repetitive test orders (esp. normal results)Repetitive test orders (esp. normal results) Incomplete understanding re: impact of low pre-test probabilityIncomplete understanding re: impact of low pre-test probability Poor understanding of the consequences of overutilizationPoor understanding of the consequences of overutilization Patient pressurePatient pressure Defensive testingDefensive testing Perverse financial incentives (more tests = more revenue)Perverse financial incentives (more tests = more revenue) * Astion ML. 2006. Interventions that improve laboratory utilization: from gentle guidance to strong restrictions. Laboratory Errors and Patient Safety. 2(4):8-9 Ordering test panels rather than ala carte’Ordering test panels rather than ala carte’ Ordering tests as groupsOrdering tests as groups Repetitive test orders (esp. normal results)Repetitive test orders (esp. normal results) Incomplete understanding re: impact of low pre-test probabilityIncomplete understanding re: impact of low pre-test probability Poor understanding of the consequences of overutilizationPoor understanding of the consequences of overutilization Patient pressurePatient pressure Defensive testingDefensive testing Perverse financial incentives (more tests = more revenue)Perverse financial incentives (more tests = more revenue) * Astion ML. 2006. Interventions that improve laboratory utilization: from gentle guidance to strong restrictions. Laboratory Errors and Patient Safety. 2(4):8-9

6. The Origin of Test Panels Technicon SMAC (1974):Technicon SMAC (1974): Sequential Multiple Analyzer with ComputerSequential Multiple Analyzer with Computer Technicon SMAC (1974):Technicon SMAC (1974): Sequential Multiple Analyzer with ComputerSequential Multiple Analyzer with Computer

7. Modern ‘Discreet’ Analyzers

8. Ordering Test Panels A study of orders for repeat electrolyte panels indicated that 10% were medically unnecessary and in 65% of cases a single test could have substituted for the entire panel. (Baigelman et al, Intensive Care Med, 11(6) 1985)A study of orders for repeat electrolyte panels indicated that 10% were medically unnecessary and in 65% of cases a single test could have substituted for the entire panel. (Baigelman et al, Intensive Care Med, 11(6) 1985)

9. Impact of Electrolyte Reduction

10. Ordering Tests in Groups Redundant tests:Redundant tests: BUN & CreatinineBUN & Creatinine Troponin & CK-MBTroponin & CK-MB ALT & ASTALT & AST Tests that just seem to trip off the tongue:Tests that just seem to trip off the tongue: Calcium, magnesium, phosphorusCalcium, magnesium, phosphorus PT & PTTPT & PTT T3, T4 & TSHT3, T4 & TSH Redundant tests:Redundant tests: BUN & CreatinineBUN & Creatinine Troponin & CK-MBTroponin & CK-MB ALT & ASTALT & AST Tests that just seem to trip off the tongue:Tests that just seem to trip off the tongue: Calcium, magnesium, phosphorusCalcium, magnesium, phosphorus PT & PTTPT & PTT T3, T4 & TSHT3, T4 & TSH

11. Separating BUN & Creatinine

12. Repetitive Testing A study of the impact on serum potassium orders using a simple algorithm based on prior tests being normal or abnormal could reduce potassium testing by 34% (Schubart et al, MEDINFO 2001)A study of the impact on serum potassium orders using a simple algorithm based on prior tests being normal or abnormal could reduce potassium testing by 34% (Schubart et al, MEDINFO 2001) Renal function: BUN, CreatinineRenal function: BUN, Creatinine CBC & CBC w/differentialCBC & CBC w/differential A study of the impact on serum potassium orders using a simple algorithm based on prior tests being normal or abnormal could reduce potassium testing by 34% (Schubart et al, MEDINFO 2001)A study of the impact on serum potassium orders using a simple algorithm based on prior tests being normal or abnormal could reduce potassium testing by 34% (Schubart et al, MEDINFO 2001) Renal function: BUN, CreatinineRenal function: BUN, Creatinine CBC & CBC w/differentialCBC & CBC w/differential

13. Problems with Test Over- utilization Patient issuesPatient issues Pain & morbidity from repeated venipuncturesPain & morbidity from repeated venipunctures Iatrogenic anemiaIatrogenic anemia Medical issuesMedical issues Follow-up on clinically irrelevant abnormalsFollow-up on clinically irrelevant abnormals Tracking just the ‘numbers’ instead of the entire clinical pictureTracking just the ‘numbers’ instead of the entire clinical picture Instituting inappropriate therapiesInstituting inappropriate therapies Economic & Environmental issuesEconomic & Environmental issues Lack of reimbursement for inpatient testingLack of reimbursement for inpatient testing Biohazardous waste generationBiohazardous waste generation Patient issuesPatient issues Pain & morbidity from repeated venipuncturesPain & morbidity from repeated venipunctures Iatrogenic anemiaIatrogenic anemia Medical issuesMedical issues Follow-up on clinically irrelevant abnormalsFollow-up on clinically irrelevant abnormals Tracking just the ‘numbers’ instead of the entire clinical pictureTracking just the ‘numbers’ instead of the entire clinical picture Instituting inappropriate therapiesInstituting inappropriate therapies Economic & Environmental issuesEconomic & Environmental issues Lack of reimbursement for inpatient testingLack of reimbursement for inpatient testing Biohazardous waste generationBiohazardous waste generation

14. Studies on iatrogenic anemia Smoller et al NEJM 314, 1986:Smoller et al NEJM 314, 1986: General wards: 1.1 draws/d, Ave. 12.4 mL/d, Total 175 mL for hospitalizationGeneral wards: 1.1 draws/d, Ave. 12.4 mL/d, Total 175 mL for hospitalization ICU: 3.4 draws/d, Ave. 41.5 mL/d, Total 762.2mLICU: 3.4 draws/d, Ave. 41.5 mL/d, Total 762.2mL ICU w/Art line: 4.0 draws/d, Total 944 mLICU w/Art line: 4.0 draws/d, Total 944 mL Low et al Chest 108(1) Jul, 1995:Low et al Chest 108(1) Jul, 1995: Presence of Art. Line in ICU patients increased blood volume loss from phlebotomy by 44%Presence of Art. Line in ICU patients increased blood volume loss from phlebotomy by 44% Smoller et al NEJM 314, 1986:Smoller et al NEJM 314, 1986: General wards: 1.1 draws/d, Ave. 12.4 mL/d, Total 175 mL for hospitalizationGeneral wards: 1.1 draws/d, Ave. 12.4 mL/d, Total 175 mL for hospitalization ICU: 3.4 draws/d, Ave. 41.5 mL/d, Total 762.2mLICU: 3.4 draws/d, Ave. 41.5 mL/d, Total 762.2mL ICU w/Art line: 4.0 draws/d, Total 944 mLICU w/Art line: 4.0 draws/d, Total 944 mL Low et al Chest 108(1) Jul, 1995:Low et al Chest 108(1) Jul, 1995: Presence of Art. Line in ICU patients increased blood volume loss from phlebotomy by 44%Presence of Art. Line in ICU patients increased blood volume loss from phlebotomy by 44%

15. Impacts of Iatrogenic anemia Critically ill patients may not have the bone marrow reserve or erythropoietin drive to compensate for iatrogenic blood loss.Critically ill patients may not have the bone marrow reserve or erythropoietin drive to compensate for iatrogenic blood loss. Transfusion to correct for this anemia has been shown to negatively impact long term survivalTransfusion to correct for this anemia has been shown to negatively impact long term survival Other risks of phlebotomy:Other risks of phlebotomy: Nerve damage, arterial damage, venous sclerosis, infectionNerve damage, arterial damage, venous sclerosis, infection Critically ill patients may not have the bone marrow reserve or erythropoietin drive to compensate for iatrogenic blood loss.Critically ill patients may not have the bone marrow reserve or erythropoietin drive to compensate for iatrogenic blood loss. Transfusion to correct for this anemia has been shown to negatively impact long term survivalTransfusion to correct for this anemia has been shown to negatively impact long term survival Other risks of phlebotomy:Other risks of phlebotomy: Nerve damage, arterial damage, venous sclerosis, infectionNerve damage, arterial damage, venous sclerosis, infection

16. Irrelevant ‘abnormals’ Virtually all quantitative laboratory test ‘normal ranges’ are based on the mean +/- 2 SD (95% confidence interval) for a subject populationVirtually all quantitative laboratory test ‘normal ranges’ are based on the mean +/- 2 SD (95% confidence interval) for a subject population 5% of normal patients will have values that lie outside this range (magnified for ill patients)5% of normal patients will have values that lie outside this range (magnified for ill patients) Virtually all quantitative laboratory test ‘normal ranges’ are based on the mean +/- 2 SD (95% confidence interval) for a subject populationVirtually all quantitative laboratory test ‘normal ranges’ are based on the mean +/- 2 SD (95% confidence interval) for a subject population 5% of normal patients will have values that lie outside this range (magnified for ill patients)5% of normal patients will have values that lie outside this range (magnified for ill patients) 2.5%

17. Irrelevant ‘abnormals’ If a patient has 10 tests ordered, each with a 5% chance that the test may have a result outside the normal range. Then there is a 50% chance that at least one test will have an ‘abnormal’ resultIf a patient has 10 tests ordered, each with a 5% chance that the test may have a result outside the normal range. Then there is a 50% chance that at least one test will have an ‘abnormal’ result This is especially true with ordering chemistry ‘panels’This is especially true with ordering chemistry ‘panels’ If a patient has 10 tests ordered, each with a 5% chance that the test may have a result outside the normal range. Then there is a 50% chance that at least one test will have an ‘abnormal’ resultIf a patient has 10 tests ordered, each with a 5% chance that the test may have a result outside the normal range. Then there is a 50% chance that at least one test will have an ‘abnormal’ result This is especially true with ordering chemistry ‘panels’This is especially true with ordering chemistry ‘panels’

18. Economics & Environment The vast majority of inpatient care is covered by DRG or per diem paymentsThe vast majority of inpatient care is covered by DRG or per diem payments Laboratory tests are not individually reimbursed and merely represent cost against the what the hospital is paidLaboratory tests are not individually reimbursed and merely represent cost against the what the hospital is paid The 3 UCSF Clinical Laboratories generate approx. 11,500 lbs of biowaste per monthThe 3 UCSF Clinical Laboratories generate approx. 11,500 lbs of biowaste per month Cost to incinerate this waste is approx. $88K per yearCost to incinerate this waste is approx. $88K per year The vast majority of inpatient care is covered by DRG or per diem paymentsThe vast majority of inpatient care is covered by DRG or per diem payments Laboratory tests are not individually reimbursed and merely represent cost against the what the hospital is paidLaboratory tests are not individually reimbursed and merely represent cost against the what the hospital is paid The 3 UCSF Clinical Laboratories generate approx. 11,500 lbs of biowaste per monthThe 3 UCSF Clinical Laboratories generate approx. 11,500 lbs of biowaste per month Cost to incinerate this waste is approx. $88K per yearCost to incinerate this waste is approx. $88K per year

19. The Solution? Approaches that have been triedApproaches that have been tried Place limits on housestaff ordersPlace limits on housestaff orders Provide information on test costsProvide information on test costs Requisition designRequisition design EMR warnings and remindersEMR warnings and reminders EducationEducation IncentivesIncentives Approaches that have been triedApproaches that have been tried Place limits on housestaff ordersPlace limits on housestaff orders Provide information on test costsProvide information on test costs Requisition designRequisition design EMR warnings and remindersEMR warnings and reminders EducationEducation IncentivesIncentives

20. Factors that Impact Laboratory Test Results & Interpretation Pre-analytic issuesPre-analytic issues Diagnostic testing issuesDiagnostic testing issues Pre-test probabilityPre-test probability Appropriateness of test in your patientAppropriateness of test in your patient Impact of the test result on care decisionsImpact of the test result on care decisions Chasing ‘diagnostic certainty’Chasing ‘diagnostic certainty’ Impact of other disorders, therapy on resultsImpact of other disorders, therapy on results Monitoring issuesMonitoring issues Which test is going to be used?Which test is going to be used? How fast does the test change?How fast does the test change? What is the impact of monitoring on clinical care?What is the impact of monitoring on clinical care? Pre-analytic issuesPre-analytic issues Diagnostic testing issuesDiagnostic testing issues Pre-test probabilityPre-test probability Appropriateness of test in your patientAppropriateness of test in your patient Impact of the test result on care decisionsImpact of the test result on care decisions Chasing ‘diagnostic certainty’Chasing ‘diagnostic certainty’ Impact of other disorders, therapy on resultsImpact of other disorders, therapy on results Monitoring issuesMonitoring issues Which test is going to be used?Which test is going to be used? How fast does the test change?How fast does the test change? What is the impact of monitoring on clinical care?What is the impact of monitoring on clinical care?

21. Factors Impacting Laboratory Tests

22. Pre-analytic Test Issues Time of sample collectionTime of sample collection Proper collection techniqueProper collection technique Proper labelingProper labeling Proper storage and transportProper storage and transport Time of sample collectionTime of sample collection Proper collection techniqueProper collection technique Proper labelingProper labeling Proper storage and transportProper storage and transport

23. Time of Collection Relative to time of management decisionsRelative to time of management decisions Relative to therapyRelative to therapy Platelet counts after transfusionPlatelet counts after transfusion Drug levels: relative to doseDrug levels: relative to dose Peak: PO vs. IVPeak: PO vs. IV TroughTrough Relative to time of dayRelative to time of day CortisolCortisol Relative to time of management decisionsRelative to time of management decisions Relative to therapyRelative to therapy Platelet counts after transfusionPlatelet counts after transfusion Drug levels: relative to doseDrug levels: relative to dose Peak: PO vs. IVPeak: PO vs. IV TroughTrough Relative to time of dayRelative to time of day CortisolCortisol

24. Proper Collection Technique Prolonged use of tourniquetProlonged use of tourniquet IV’s and line drawsIV’s and line draws Order of collectionOrder of collection Trace metal (Royal blue), Blood culturesTrace metal (Royal blue), Blood cultures Blue; Gold/Red; Green; PurpleBlue; Gold/Red; Green; Purple Proper fillingProper filling Proper mixingProper mixing Special needsSpecial needs Prolonged use of tourniquetProlonged use of tourniquet IV’s and line drawsIV’s and line draws Order of collectionOrder of collection Trace metal (Royal blue), Blood culturesTrace metal (Royal blue), Blood cultures Blue; Gold/Red; Green; PurpleBlue; Gold/Red; Green; Purple Proper fillingProper filling Proper mixingProper mixing Special needsSpecial needs

25. Proper Labeling The person who collects a sample should label itThe person who collects a sample should label it Double check the label before submittingDouble check the label before submitting Special Blood Bank requirementsSpecial Blood Bank requirements Check specimenCheck specimen Body fluidsBody fluids Lab policies on handling unlabeled and mislabeled samplesLab policies on handling unlabeled and mislabeled samples The person who collects a sample should label itThe person who collects a sample should label it Double check the label before submittingDouble check the label before submitting Special Blood Bank requirementsSpecial Blood Bank requirements Check specimenCheck specimen Body fluidsBody fluids Lab policies on handling unlabeled and mislabeled samplesLab policies on handling unlabeled and mislabeled samples

26. Proper Storage & Transport Refrigeration vs. Room temperatureRefrigeration vs. Room temperature Protection from lightProtection from light Transport to the labTransport to the lab Effects of cellular metabolismEffects of cellular metabolism Blood gas samplesBlood gas samples Serum chemistriesSerum chemistries Pneumatic tube considerationsPneumatic tube considerations Refrigeration vs. Room temperatureRefrigeration vs. Room temperature Protection from lightProtection from light Transport to the labTransport to the lab Effects of cellular metabolismEffects of cellular metabolism Blood gas samplesBlood gas samples Serum chemistriesSerum chemistries Pneumatic tube considerationsPneumatic tube considerations

27. What is the effect of Pre-test probability? The pretest probability of disease is critically important to test orderingThe pretest probability of disease is critically important to test ordering If the disorder has a low pretest probability then even a very sensitive and specific test may have little clinical utilityIf the disorder has a low pretest probability then even a very sensitive and specific test may have little clinical utility If the pretest probability is very high tests may not provide much (if any) additional ‘certainty’ of the diagnosisIf the pretest probability is very high tests may not provide much (if any) additional ‘certainty’ of the diagnosis The pretest probability of disease is critically important to test orderingThe pretest probability of disease is critically important to test ordering If the disorder has a low pretest probability then even a very sensitive and specific test may have little clinical utilityIf the disorder has a low pretest probability then even a very sensitive and specific test may have little clinical utility If the pretest probability is very high tests may not provide much (if any) additional ‘certainty’ of the diagnosisIf the pretest probability is very high tests may not provide much (if any) additional ‘certainty’ of the diagnosis

28. Low pretest probability example You are thinking of ordering a test that is 95% sensitive and specificYou are thinking of ordering a test that is 95% sensitive and specific The pretest probability that the disorder is present is, however, only 10% in your patientThe pretest probability that the disorder is present is, however, only 10% in your patient Positive predictive value: 68%Positive predictive value: 68% Negative predictive value: 99%Negative predictive value: 99% only represents a 9% increase in certainty over the pretest probabilityonly represents a 9% increase in certainty over the pretest probability At a pre-test probability of 1% the PPV is only 16% and the NPV is 100%At a pre-test probability of 1% the PPV is only 16% and the NPV is 100% You are thinking of ordering a test that is 95% sensitive and specificYou are thinking of ordering a test that is 95% sensitive and specific The pretest probability that the disorder is present is, however, only 10% in your patientThe pretest probability that the disorder is present is, however, only 10% in your patient Positive predictive value: 68%Positive predictive value: 68% Negative predictive value: 99%Negative predictive value: 99% only represents a 9% increase in certainty over the pretest probabilityonly represents a 9% increase in certainty over the pretest probability At a pre-test probability of 1% the PPV is only 16% and the NPV is 100%At a pre-test probability of 1% the PPV is only 16% and the NPV is 100%

29. High pretest probability The same theoretic test (95% sensitive and 95% specific) but in a patient with a 90% likelihood of having the disorder:The same theoretic test (95% sensitive and 95% specific) but in a patient with a 90% likelihood of having the disorder: Positive predictive value: 99% (9% incr.)Positive predictive value: 99% (9% incr.) Negative predictive value: 68%Negative predictive value: 68% The same theoretic test (95% sensitive and 95% specific) but in a patient with a 90% likelihood of having the disorder:The same theoretic test (95% sensitive and 95% specific) but in a patient with a 90% likelihood of having the disorder: Positive predictive value: 99% (9% incr.)Positive predictive value: 99% (9% incr.) Negative predictive value: 68%Negative predictive value: 68%

30. When do tests add the most information? When the pretest probability is in the range of 30-70%When the pretest probability is in the range of 30-70% At a pretest probability of 50%, a test that is 95% sensitive and specific yields:At a pretest probability of 50%, a test that is 95% sensitive and specific yields: Positive predictive value: 95%Positive predictive value: 95% Negative predictive value: 95%Negative predictive value: 95% When the pretest probability is in the range of 30-70%When the pretest probability is in the range of 30-70% At a pretest probability of 50%, a test that is 95% sensitive and specific yields:At a pretest probability of 50%, a test that is 95% sensitive and specific yields: Positive predictive value: 95%Positive predictive value: 95% Negative predictive value: 95%Negative predictive value: 95%

31. Is the test appropriate for your patient? How does the patient’s diagnosis impact the test?How does the patient’s diagnosis impact the test? VTE and Protein C/S levels VTE and Protein C/S levels How does the patient’s treatment impact the test?How does the patient’s treatment impact the test? Galactose or Maltose containing medications and POCT Glucose testingGalactose or Maltose containing medications and POCT Glucose testing D-dimer in a surgical patientD-dimer in a surgical patient How do other disorders impact the test?How do other disorders impact the test? HgbA1c and shortened red cell lifespanHgbA1c and shortened red cell lifespan How does the patient’s diagnosis impact the test?How does the patient’s diagnosis impact the test? VTE and Protein C/S levels VTE and Protein C/S levels How does the patient’s treatment impact the test?How does the patient’s treatment impact the test? Galactose or Maltose containing medications and POCT Glucose testingGalactose or Maltose containing medications and POCT Glucose testing D-dimer in a surgical patientD-dimer in a surgical patient How do other disorders impact the test?How do other disorders impact the test? HgbA1c and shortened red cell lifespanHgbA1c and shortened red cell lifespan

32. Impact of the test on patient care decisions? Ask yourself….’What will I do if the test is negative/normal vs. positive/abnormal’ if the answer is essentially the same for both then the test has little utilityAsk yourself….’What will I do if the test is negative/normal vs. positive/abnormal’ if the answer is essentially the same for both then the test has little utility E.g. Haptoglobin in anemiaE.g. Haptoglobin in anemia Will the result be available before the patient is discharged?Will the result be available before the patient is discharged? Chasing diagnostic ‘certainty’Chasing diagnostic ‘certainty’ How much information is needed before a treatment is initiated or withheld?How much information is needed before a treatment is initiated or withheld? Ask yourself….’What will I do if the test is negative/normal vs. positive/abnormal’ if the answer is essentially the same for both then the test has little utilityAsk yourself….’What will I do if the test is negative/normal vs. positive/abnormal’ if the answer is essentially the same for both then the test has little utility E.g. Haptoglobin in anemiaE.g. Haptoglobin in anemia Will the result be available before the patient is discharged?Will the result be available before the patient is discharged? Chasing diagnostic ‘certainty’Chasing diagnostic ‘certainty’ How much information is needed before a treatment is initiated or withheld?How much information is needed before a treatment is initiated or withheld?

33. Questions to ask about tests used to monitor a patient How fast do I expect the test to change?How fast do I expect the test to change? What is the best monitoring test for the disorder in question?What is the best monitoring test for the disorder in question? Is more than one test needed?Is more than one test needed? How much change would trigger a therapeutic intervention?How much change would trigger a therapeutic intervention? Once an intervention is made is monitoring still needed? With the same test? At the same frequency?Once an intervention is made is monitoring still needed? With the same test? At the same frequency? How fast do I expect the test to change?How fast do I expect the test to change? What is the best monitoring test for the disorder in question?What is the best monitoring test for the disorder in question? Is more than one test needed?Is more than one test needed? How much change would trigger a therapeutic intervention?How much change would trigger a therapeutic intervention? Once an intervention is made is monitoring still needed? With the same test? At the same frequency?Once an intervention is made is monitoring still needed? With the same test? At the same frequency?

34. How fast do tests change? While many test results can change rapidly in an individual there are other tests which may only change slowly or not at all over timeWhile many test results can change rapidly in an individual there are other tests which may only change slowly or not at all over time Positive serologic studiesPositive serologic studies Enzyme levels: AST T 1/2 = 17 hr, ALT T 1/2 = 48 hr, Alk Phos T 1/2 = 7 d,, GGT T 1/2 = 9 d (28 d in hepatic Dz)Enzyme levels: AST T 1/2 = 17 hr, ALT T 1/2 = 48 hr, Alk Phos T 1/2 = 7 d,, GGT T 1/2 = 9 d (28 d in hepatic Dz) D-dimersD-dimers WBC differential (if no change in WBC)WBC differential (if no change in WBC) Understanding how rapidly a given analyte may change is important to selecting how often it should be orderedUnderstanding how rapidly a given analyte may change is important to selecting how often it should be ordered While many test results can change rapidly in an individual there are other tests which may only change slowly or not at all over timeWhile many test results can change rapidly in an individual there are other tests which may only change slowly or not at all over time Positive serologic studiesPositive serologic studies Enzyme levels: AST T 1/2 = 17 hr, ALT T 1/2 = 48 hr, Alk Phos T 1/2 = 7 d,, GGT T 1/2 = 9 d (28 d in hepatic Dz)Enzyme levels: AST T 1/2 = 17 hr, ALT T 1/2 = 48 hr, Alk Phos T 1/2 = 7 d,, GGT T 1/2 = 9 d (28 d in hepatic Dz) D-dimersD-dimers WBC differential (if no change in WBC)WBC differential (if no change in WBC) Understanding how rapidly a given analyte may change is important to selecting how often it should be orderedUnderstanding how rapidly a given analyte may change is important to selecting how often it should be ordered

35. Laboratory Manual The UCSF Clinical Laboratories maintain an on- line laboratory manual that is constantly updatedThe UCSF Clinical Laboratories maintain an on- line laboratory manual that is constantly updated http://labmed.ucsf.edu/labman/ http://labmed.ucsf.edu/labman/ It has important information about:It has important information about: Sample type and amount, incl. minimumsSample type and amount, incl. minimums Test availability and turnaround timeTest availability and turnaround time Patient preparation, collection instructions and sample handlingPatient preparation, collection instructions and sample handling Test utilization tipsTest utilization tips The UCSF Clinical Laboratories maintain an on- line laboratory manual that is constantly updatedThe UCSF Clinical Laboratories maintain an on- line laboratory manual that is constantly updated http://labmed.ucsf.edu/labman/ http://labmed.ucsf.edu/labman/ It has important information about:It has important information about: Sample type and amount, incl. minimumsSample type and amount, incl. minimums Test availability and turnaround timeTest availability and turnaround time Patient preparation, collection instructions and sample handlingPatient preparation, collection instructions and sample handling Test utilization tipsTest utilization tips