Interpretation of Lab and Basic Diagnostic Tests

Vocabulary flashcards covering diagnostic lab test principles, hematological parameters, coagulation panels, metabolic components, cardiac markers, and key clinical signs from the lecture notes.

True Positive

A test result indicating that the patient has the disease and the test is positive.

False Positive

A test result indicating that the patient does not have the disease, but the test is positive.

True Negative

A test result indicating that the patient does not have the disease and the test is negative.

False Negative

A test result indicating that the patient does have the disease, but the test is negative.

Sensitivity

The ability of a test to measure true positives and accurately identify how many people with the disease will test positive.

Specificity

The ability of a test to measure true negatives and accurately identify how many people without the disease will test negative.

Polycythemia

A condition characterized by an abnormally high red blood cell (RBC) count or hematocrit level.

Left Shift

An increase in neutrophils and bands on a white blood cell differential, which suggests a bacterial infection.

Right Shift

An increase in lymphocytes on a white blood cell differential, which suggests a viral infection.

Thrombocytopenia

A abnormally low platelet count below the normal range of $150\text{ K} - 450\text{ K/mcl}$.

Thrombocytosis

An abnormally high platelet count caused by bone marrow overproduction or secondary causes such as cancer or blood loss.

Prothrombin Time (PT)

A test with a normal range of $10 - 13\text{ seconds}$ that measures the time to convert prothrombin to thrombin, detects extrinsic pathway coagulation disorders, and evaluates Coumadin therapy effectiveness.

Activated Partial Thromboplastin Time (aPTT)

A test with a normal range of $25 - 40\text{ seconds}$ that detects intrinsic pathway coagulation disorders and measures the effectiveness of heparin therapy.

International Normalized Ratio (INR)

A standardized reporting format for Prothrombin Time (PT), where a healthy baseline is $1.0$ and the therapeutic target for Coumadin therapy is $1.5 - 2.5$.

D-Dimer Screen

A test that measures degradation products of cross-linked fibrin to assist in diagnosing deep venous thrombosis (DVT), pulmonary embolism (PE), DIC, and abruptio placenta.

Basic Metabolic Panel (Chem 7)

A panel of chemistry tests that measures sodium, potassium, chloride, bicarbonate, glucose, blood urea nitrogen (BUN), creatinine, and the BUN/creatinine ratio.

Glycohemoglobin (Hemoglobin A1C)

A compound formed during prolonged hyperglycemia whose percent saturation indicates average blood glucose control over the previous 3 to 4 months.

Blood Urea Nitrogen (BUN)

A measurement of urea—a waste product of protein metabolism cleared exclusively by the kidneys—with a normal range of $8 - 15\text{ mg/dL}$.

Creatinine

A waste product derived from skeletal muscle that is measured to assess renal function, with normal values of $0.6 - 1.4\text{ mg/dL}$ in men and $0.6 - 1.1\text{ mg/dL}$ in women.

Chvostek Sign

A physical finding of hypocalcemia elicited by tapping the face, resulting in an exaggerated muscle twitch.

Trousseau Sign

A physical finding of hypocalcemia elicited by inflating a blood pressure cuff on the upper arm, resulting in hand cramps.

Lactate (Lactic Acid)

A product of anaerobic metabolism that builds up when tissue perfusion is inadequate, having a normal value of $< 2\text{ mmol/L}$.

Uric Acid

The end-product of purine metabolism that becomes elevated in patients with Gout.

Troponin

Contractile proteins of the myofibrils measured as a highly specific cardiac marker for myocardial necrosis.

B-natriuretic Peptide (BNP)

A peptide in the cardiac ventricles with a normal range of $5 - 100\text{ pg/dL}$ that increases during high ventricular filling pressures to signal abnormal ventricular function or congestive heart failure.

Lipase

A pancreatic enzyme that breaks down lipids, featuring a normal reference range of $0 - 160\text{ U/L}$ and serving as the most specific laboratory indicator for pancreatitis.