ASCP MLA key terms

The standardized sequence in which blood collection tubes are filled so that additives from one tube do not contaminate the next. Coagulation tubes are drawn before tubes containing clot activators or other additives, following CLSI guidance.

Rupture of red blood cells that releases hemoglobin and intracellular contents into serum or plasma. It falsely raises potassium, LDH, and AST and interferes with many spectrophotometric assays; common causes include rough handling, small needles, and prolonged tourniquet time.

A collection tube containing a clot activator and a thixotropic gel. After centrifugation the gel forms a barrier between the clotted cells and serum, yielding cell-free serum for chemistry testing.

A lavender-top tube containing K2 or K3 ethylenediaminetetraacetic acid, which chelates calcium and prevents clotting. It is the preferred tube for complete blood counts and many molecular tests; excess EDTA can falsely lower calcium and alter cell morphology.

A light blue-top tube containing 3.2% buffered sodium citrate, which reversibly binds calcium. It must be filled to the indicated line to maintain the required 9:1 blood-to-anticoagulant ratio for coagulation testing.

A urine collection technique in which the genital area is cleaned, the first portion of urine is voided and discarded, and the midstream portion is captured. It reduces contamination from skin flora and is used for routine culture.

A documented, unbroken record of everyone who collected, handled, stored, and received a specimen. It is required for forensic, workplace drug-testing, and other legally defensible samples.

A dermal stick, usually of a fingertip or infant heel, used to obtain small blood volumes when venous access is difficult. Excessive squeezing should be avoided because it causes hemolysis and dilution with tissue fluid.

The complete blood count, a panel that measures red cell count, white cell count, platelets, hemoglobin, hematocrit, and red cell indices. It is used to screen for and monitor anemia, infection, and hematologic malignancy.

The percentage of blood volume occupied by red cells, measured by centrifugation or calculated from red cell count and mean corpuscular volume. It is falsely elevated by dehydration and falsely lowered by overhydration.

Mean corpuscular volume, the average red cell size expressed in femtoliters. It classifies anemia as microcytic, normocytic, or macrocytic and is calculated from hematocrit divided by red cell count.

The percentage of newly released immature red cells that still contain residual RNA. It indicates bone marrow response to anemia; a corrected count adjusts for the degree of anemia.

A thin film of blood spread on a slide, stained with Wright or Giemsa stain and examined microscopically. It allows evaluation of cell morphology, a manual differential count, and an estimate of platelet number.

The erythrocyte sedimentation rate, the distance red cells fall in a vertical tube in one hour. It is a nonspecific marker of inflammation influenced by age, sex, anemia, and plasma protein concentrations.

The prothrombin time measures the extrinsic and common coagulation pathways; the INR standardizes the result across reagent lots. It is used to monitor warfarin therapy and is prolonged by factor deficiency, liver disease, and vitamin K deficiency.

The activated partial thromboplastin time measures the intrinsic and common coagulation pathways. It is used to monitor unfractionated heparin therapy and to detect factor deficiencies, and it requires a properly filled citrate tube.

A waste product of muscle creatine metabolism that is cleared mainly by glomerular filtration. Serum creatinine is used to estimate kidney function and is affected by muscle mass, diet, and certain drugs.

The estimated glomerular filtration rate, calculated from serum creatinine plus age and sex. It estimates kidney function and is used to stage chronic kidney disease.

Glycated hemoglobin, the fraction of hemoglobin with glucose irreversibly attached. It reflects average blood glucose over roughly the previous two to three months and is used to diagnose and monitor diabetes.

A structural protein released from injured heart muscle. It is the preferred marker of myocardial injury because it is highly specific to the heart, and serial measurements show the characteristic rise and fall of infarction.

The calculated difference between measured cations, mainly sodium, and measured anions, chloride plus bicarbonate. It helps classify a metabolic acidosis as high gap or normal gap and narrow the cause.

Thyroid-stimulating hormone, produced by the pituitary gland. It is the first-line test of thyroid function because it changes inversely with thyroid hormone levels, rising in primary hypothyroidism and falling in hyperthyroidism.

Any endogenous substance such as hemoglobin, bilirubin, or lipid, or any exogenous substance, that alters a measured result without changing the true analyte concentration. Interference indices and dilution or recovery studies help detect it.

A differential stain using crystal violet, iodine, decolorizer, and safranin that separates bacteria into gram-positive purple cells and gram-negative pink cells. It gives rapid preliminary identification and guides early therapy from clinical specimens.

The minimum inhibitory concentration, the lowest antimicrobial concentration that visibly inhibits growth of an organism in vitro. It is used to classify the isolate as susceptible, intermediate, or resistant to that drug.

One viable microbial cell or clump that grows into a single visible colony on a culture plate. Counting colony-forming units per milliliter quantifies bacterial burden, for example in urine specimens.

A nucleic acid amplification test that detects specific DNA or RNA sequences, usually by polymerase chain reaction. It offers high sensitivity and rapid identification of pathogens, including organisms that are difficult or slow to culture.

Methicillin-resistant Staphylococcus aureus, resistant to beta-lactam antibiotics through the mecA gene and altered penicillin-binding protein. It is a major cause of health care-associated and community-acquired infection, detected by cefoxitin disk testing or molecular methods.

Internal procedures that use materials with known values, run alongside patient samples, to verify that a test system performs within acceptable limits before patient results are reported.

A control chart that plots quality control values over time against the mean and plus or minus 1, 2, and 3 standard deviation limits. It visually reveals random error, shifts, and trends in test performance.

A set of multirule criteria, such as 1-2s, 1-3s, 2-2s, R-4s, 4-1s, and 10x, applied to quality control results to decide whether an analytical run should be rejected.

An external program that sends samples of unknown value to laboratories for analysis and compares each result with peer laboratories. Acceptable performance is required for accreditation and demonstrates analytical accuracy.

A comparison of a patient's current result with a previous result from a defined time interval. A change exceeding set limits is flagged because it may indicate specimen mix-up, collection error, or a true clinical change.

A test result that indicates imminent danger to the patient and requires immediate notification of the responsible caregiver, with documentation of who was notified and when.

The corrective and preventive action process: systematic investigation of a problem to find its root cause, followed by documented actions that correct it and prevent recurrence within the laboratory quality system.

The process of comparing an instrument's response against solutions of known concentration to establish the mathematical relationship between signal and analyte concentration. It is verified with quality control materials before patient testing.

The laboratory decision to refuse and not test a sample because it fails acceptance criteria such as incorrect tube, insufficient volume, unlabeled container, gross hemolysis, or delayed transport. The reason is documented and the collector is notified.