1 / 33

Introduction to Laboratory Medicine

Introduction to Laboratory Medicine. Roger L. Bertholf, Ph.D. Some SHJ Lab Statistics. Number of employees: 130 Number of tests/year: 1.5 million Yearly budget: $16 million Yearly revenue: $70 million Net $25 million. Laboratory organization. Core Laboratory (73% of volume)

Jims
Télécharger la présentation

Introduction to Laboratory Medicine

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to Laboratory Medicine Roger L. Bertholf, Ph.D.

  2. Some SHJ Lab Statistics • Number of employees: 130 • Number of tests/year: 1.5 million • Yearly budget: $16 million • Yearly revenue: $70 million • Net $25 million

  3. Laboratory organization • Core Laboratory (73% of volume) • Chemistry, hematology, toxicology, immuno-chemistry, special chemistry, coagulation, urinalysis • Microbiology (16 % of volume) • Blood/urine cultures, serology • Transfusion Services (3% of volume) • Blood typing and cross-matching

  4. Chemistry • Electrolytes, glu, BUN, creat, phos, TP, Bili, Mg, Ca, cholesterol, triglycerides, etc. • Blood gases: pO2, pCO2, pH, calc. Parameters • Immunochemistry: endocrine, specific protein, tumor markers • Toxicology: DAU, TDM • Urinalysis • Special Chemistry: electrophoresis, L/S ratio, FLM, osmometry

  5. SHJ Chemistry Instruments • Roche/Hitachi Modular and 914 • Chemistries and homogeneous immunoassays • Roche Elecsys 2010 • Heterogeneous immunoassays • NOVA M (whole blood gas/electrolytes) • Abbott IMx • Yellow Iris

  6. Hematology • CBC/Diff • Coagulation • Microscopy

  7. SHJ Hematology Instruments • Abbott Cell Dyne 4000 • CBC, Auto differential • Organon Technika MDA • Coagulation

  8. Microbiology • Cultures • Blood • Urine • Sputum, wound, etc. • Antibiotic sensitivity • Serology • Viral Ab, Ag testing

  9. Point of Care Testing • Instruments are available that can perform certain tests at remote locations, such as at the bedside on in a clinical care unit • Blood glucose • Urinalysis • Blood gases • Electrolytes/BUN/Creatinine • Cardiac markers (Troponin I & T, CK-MB) • Coagulation (ACT) • POC tests are nearly always more expensive, than the same tests performed in the central laboratory

  10. POCT at SHJ • Blood glucose (Not under lab license) • Electrolytes on the GEM Premier in the OR • ACT in the OR and Cardiac Catheterization Lab • Urinalysis (not under lab license)

  11. Reasons for POC testing • Tests are of urgent importance, and results will affect the immediate management of the patient • Blood gases, electrolytes • Tests are so common, simple and cheap that it is more economical to perform them at the point of care • Blood glucose, urinalysis

  12. SHJ Blood Gas Lab • Operated by Respiratory Therapy • Performs blood gases and whole blood electrolytes/BUN/Creatinine/Glucose • Gases fall under RT license • Chemistries fall under the lab license • Serves MICU, CCU, PICU, NICU, SICU • Performs all co-oximetry

  13. Steps in obtaining a laboratory test • Written order is placed • Specimen is collected and properly labeled • Specimen and order are transported to the lab • The specimen is accessioned in the lab • The specimen is processed • The specimen is analyzed • The results are reviewed and verified by an MT • The results are released to the patient’s record

  14. How long steps 4-7 take (P1 orders)

  15. How long steps 4-7 take (STAT)

  16. Sources of error in laboratory results • Pre-analytical • Analytical • Post-analytical

  17. Pre-analytical errors • Collection • Was the right tube used? • Was venipuncture performed correctly? • Was the specimen properly stored? • Identification • Was the blood collected from the correct patient? • Was the blood correctly labeled? • Patient name, ID, date, time of collection, phlebotomist

  18. Collection tubes • Red-top tubes contain no anticoagulants or preservatives • Red-top tubes are used for collecting serum • 10-15 minutes is required to allow blood to clot before centrifuging • Used for blood bank specimens, some chemistries

  19. Collection tubes • Gold (and “tiger”) top tubes contain a gel that forms a physical barrier between the serum and cells after centrifugation • No other additives are present • Gel barrier may affect some lab tests

  20. Collection tubes • Gray-top tubes contain either: • Sodium fluoride and potassium oxalate, or • Sodium iodoacetate • Both perservatives stabilize glucose in plasma • NaF/oxalate inhibits enolase • Iodoacetate inhibits glucose-3-phosphate dehydrogenase

  21. Collection tubes • Green-top tubes contain either the sodium or lithium salt of heparin • The amount of Na+ or Li+ is insignificant • Heparin inhibits thrombin, so blood does not clot (plasma) • The advantage of plasma is that no time is wasted waiting for the specimen to clot

  22. Collection tubes • Lavender-top tubes contain EDTA, which chelates calcium and inhibits coagulation • Used for hematology, and some chemistries

  23. Collection tubes • Blue-top tubes contain sodium citrate, which chelates calcium and inhibits coagulation • The blood/anticoagulant ratio must be precisely known, since the tubes are used for coagulation studies.

  24. Collection tubes • Brown and Royal Blue top tubes are specially cleaned for trace metal studies • Brown-top tubes are used for Pb analysis • Royal blue-top tubes are used for other trace element studies (acid washed)

  25. Plasma/Serum differences • Plasma concentration greater than serum: • Ca (+0.9%), LD (+2.7%), TP (+4.0%) • Plasma concentration less than serum: • Alb (-1.3%), ALKP (-1.6%), HCO3- (-1.8%), CK (-2.1%), PO4= (-7.0%), K+ (-8.4%)

  26. Prolonged venous stasis • Increases TP, Fe, cholesterol, AST, bilirubin • Decreases potassium

  27. Supine vs. sitting or standing • The following may decrease by 5-15% in the supine patient: • Total protein • Albumin • Lipids • Iron • Calcium • Enzymes • Ig • Thyroxine

  28. Significantly affected by hemolysis: • Total protein, albumin, lipids, iron, calcium, enzymes, bilirubn, cholesterol, triglycerides, norepinephrine, renin, aldosterone, potassium, magnesium, phosphorous

  29. Specimens requiring special handling • Should be placed immediately on ice • Lactate • Ammonia • Acid phosphatase • Plasma catecholamines

  30. Exertion-related changes • Recent strenuous exercise increases: • Acid phosphatase, ALT, AST, creatinine, phosphorous, CK • Recent strenuous exercise decreases: • Iron, lipids, potassium

  31. Other factors affecting lab results • Diurnal variations • Cortisol, iron, estriol, glucose, catecholamines • Age • Creatinine, BUN, ALKP, drug metabolism • Smoking • Ammonia, CO-Hb

  32. Specimen identification • One of the commonest sources of erroneous lab results is misidentified specimens • CAP and other accrediting agencies require the lab to have a clear and rational policy for identifying specimens, and handling misidentified specimens • The blood bank has stricter requirements for specimen identification

  33. Misidentified specimens at SHJ 29: Delay in obtaining lab results 26: Specimen collected/labeled/registered with wrong patient 46: Specimen unlabeled/mislabeled/labeled incompletely

More Related