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) 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

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

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

Hematology CBC/Diff Coagulation Microscopy

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

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

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

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)

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

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

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

How long steps 4-7 take (P1 orders)

How long steps 4-7 take (STAT)

Sources of error in laboratory results Pre-analytical Analytical Post-analytical

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

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

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

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

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

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

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.

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)

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%)

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

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

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

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

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

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

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

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