Clinical Biochemistry and Laboratory Diagnostics

Vocabulary practice flashcards covering basic clinical biochemistry principles, laboratory safety, specimen collection, spectrophotometry, carbohydrate, lipid, protein, renal, liver, and enzymatic assays, urinalysis, and microscopic sediment evaluation.

Chemical Burn Management (Laboratory First Aid)

Immediate first aid protocol for laboratory exposures: for acid burns, flush with water and neutralize with $8\%$ sodium bicarbonate; for base burns, neutralize with $3\%$ picric acid or boric acid; for eye contamination, flush continuously in an eyewash cup with water or $1\%$ sodium bicarbonate (for acids) or $1\%$ boric acid (for bases).

Beer-Lambert Law (Spectrophotometry Principle)

The optical principle stating that optical density ($OD$) is directly proportional to solute concentration ($C$) at a constant light path length, allowing unknown concentration to be calculated via the formula: $C = \frac{OD - OD_{\text{blank}}}{OD_0 - OD_{\text{blank}}} \times C_0$.

Anticoagulated Blood Centrifugation Layers

The stratification of whole blood into three layers following centrifugation ($3000\,\text{rpm}$ for $5\,\text{min}$): an upper clear plasma layer containing fibrinogen, an intermediate whitish buffy coat containing leukocytes and platelets, and a dense sediment of red blood cells at the bottom.

Lumbar Puncture (Cerebrospinal Fluid Sampling)

The procedural aspiration of cerebrospinal fluid ($\text{CSF}$) from the subarachnoid space performed in either a lateral recumbent or sitting posture, collected into two consecutive tubes to differentiate a traumatic tap from true subarachnoid hemorrhage.

Molisch Test

A general qualitative reaction for carbohydrates where $\alpha$-naphthol in ethanol reacts with concentrated sulfuric acid ($H_2SO_4$) to dehydrate sugars into furfural derivatives, producing a distinct violet/purple ring at the phase interface.

Fehling's Reaction

A qualitative test for reducing sugars using alkaline cupric tartrate reagent (Fehling's A and B); upon boiling, reducing sugars oxidize and reduce cupric ions ($Cu^{2+}$) to form a characteristic brick-red precipitate of cuprous oxide ($Cu_2O$).

Lugol's Iodine Test

A qualitative starch identification assay in which triiodide anions entrap within the amylose helical structure to yield a deep blue complex, whereas glycogen forms a reddish-brown color.

Nelson-Somogyi / Arsenomolybdate Glucose Assay

A photometric glucose quantification method where deproteinized plasma reduces cupric ions to cuprous oxide ($Cu_2O$), which subsequently reduces arsenomolybdate reagent to molybdenum blue, measured photometrically at $520\,\text{nm}$.

Benedict's Test

A semi-quantitative urinary glucose reduction assay using copper sulfate, sodium carbonate, and sodium citrate; color transitions from blue (negative) to green ($+$), yellowish-green ($++$), orange-brown ($+++$), and brick-red ($++++$) correlate with glucose concentrations up to $> 20\,\text{g/L}$.

Chylomicrons (CM)

Large lipoprotein complexes synthesized in the intestinal mucosa responsible for packaging and transporting exogenous dietary lipids from the intestines through the lymphatic system and blood circulation to peripheral tissues and the liver.

Friedewald Formula

A mathematical formula used to estimate low-density lipoprotein cholesterol when serum triglyceride levels are below $400\,\text{mg/dL}$: $\text{LDL-C} = \text{Total Cholesterol} - \text{HDL-C} - \frac{\text{Triglycerides}}{5}$ (in $\text{mg/dL}$).

Total Cholesterol Enzymatic Assay (CHOD-PAP)

An endpoint colorimetric method utilizing cholesterol esterase and cholesterol oxidase to generate hydrogen peroxide ($H_2O_2$), which couples with 4-aminophenazone and phenol via peroxidase to form a red-pink quinoneimine dye measured at $500\,\text{nm}$.

Triglycerides Enzymatic Assay (GPO-PAP)

An enzymatic endpoint assay where lipoprotein lipase, glycerol kinase, and glycerol-3-phosphate oxidase sequentially break down triglycerides to yield $H_2O_2$, which oxidatively condenses with 4-chlorophenol and 4-aminoantipyrine to form a pink quinoneimine dye measured at $505\,\text{nm}$.

Sodium Nitroprusside Reaction (Legal / Rothera Test)

A qualitative urinalysis assay for ketone bodies where acetoacetic acid and acetone react with sodium nitroprusside in an alkaline ammonium hydroxide ($NH_4OH$) medium, stabilized by acetic acid, to form an intense purple ring at the liquid junction.

Biuret Reaction (Gornall Method)

A photometric assay for total serum protein ($60 - 80\,\text{g/L}$) in which copper ions ($Cu^{2+}$) coordinate with two or more peptide bonds in an alkaline solution to produce a violet-pink complex with maximum absorbance at $530\,\text{nm}$.

Uricase-Peroxidase Assay

An enzymatic colorimetric quantification method where uricase oxidizes uric acid to allantoin, $CO_2$, and $H_2O_2$; peroxidase then couples $H_2O_2$ with DHBS and 4-aminoantipyrine (4-AAP) to produce a pink quinoneimine dye measured at $505\,\text{nm}$.

Urease-GLDH Kinetic Method

A fixed-time enzymatic UV assay for serum urea wherein urease converts urea to ammonia ($NH_4^+$), which is consumed by glutamate dehydrogenase (GLDH) in the presence of $\alpha$-ketoglutarate and $NADH$; the rate of decrease in absorbance at $340\,\text{nm}$ is directly proportional to urea concentration.

Jaffé Reaction

A classic colorimetric reaction for measuring creatinine based on its reaction with picric acid in an alkaline environment to form a bright yellow-orange creatinine-picrate complex measured photometrically at $505\,\text{nm}$.

Creatinine Clearance ($C_{cr}$)

The volume of blood plasma cleared of creatinine per unit time, evaluated via: $C_{cr} = \frac{[U_{\text{creatinine}}] \times V_{24\text{h}}}{[P_{\text{creatinine}}] \times 1440}$ (normal reference range: $98 - 156\,\text{mL/min}$ for males, $95 - 160\,\text{mL/min}$ for females).

CYBOW 3 Urinalysis Strips

A commercial dry-reagent test strip designed to semi-quantitatively screen urine for protein (tetrabromophenol blue indicator), pH (methyl red and bromothymol blue), and glucose (glucose oxidase/peroxidase chromogen system), read precisely at $60\,\text{seconds}$.

Diazo Bilirubin Assay

The photometric quantification of direct and total bilirubin based on coupling with diazotized sulfanilic acid (sulfodiazonium salt) under acidic conditions to form red-purple azobilirubin, measured photometrically at $540 - 550\,\text{nm}$.

Mayer's Hemoglobin Reaction

A chemical screening test for hematuria and hemoglobinuria based on the pseudoperoxidase activity of heme, which catalytically oxidizes reduced alkaline phenolphthalein reagent in the presence of hydrogen peroxide ($H_2O_2$) to produce an immediate bright pink/red color.

Alanine Aminotransferase (ALT / GPT) IFCC Assay

A continuous UV kinetic method in which ALT catalyzes transamination between L-alanine and 2-oxoglutarate to yield pyruvate and glutamate; lactate dehydrogenase (LDH) subsequently reduces pyruvate to L-lactate with concurrent oxidation of $NADH$ to $NAD^+$, monitored at $340\,\text{nm}$.

Aspartate Aminotransferase (AST / GOT) IFCC Assay

A continuous UV kinetic assay wherein AST converts L-aspartate and 2-oxoglutarate to oxaloacetate and L-glutamate; malate dehydrogenase (MDH) then reduces oxaloacetate to malate with oxidation of $NADH$ to $NAD^+$, monitored at $340\,\text{nm}$.

Urine Sediment Microscopy

The brightfield microscopic examination of centrifuged urinary sediment to classify elements into organized structures (erythrocytes, leukocytes, epithelial cells, casts, spermatozoa) and unorganized crystalline elements (such as envelope-like calcium oxalate crystals).

Vaginal Epithelial Cells in Urine

Large, polygonal squamous epithelial cells featuring abundant cytoplasm and a small, round central nucleus, typically present in urine sediment due to contamination from the external genitalia or lower urinary tract.

Wohlgemuth Unit

The standard enzymatic measure defined as the quantity of urinary amylase required to completely hydrolyze $1\,\text{mL}$ of a $0.1\%$ ($1‰$) starch solution at $37^\circ\text{C}$ in $30\,\text{minutes}$, determined via serial dilution and iodine indicator.

CNPG-G2 Direct Kinetic Amylase Method

A kinetic photometric assay measuring $\alpha$-amylase activity through the direct catalytic cleavage of 2-chloro-4-nitrophenyl-$\beta$-D-galactopyranosylmaltoside ($\text{Gal-G2-CNP}$) into free chloro-nitrophenol ($\text{CNP}$), tracked continuously at $405\,\text{nm}$.

CK-MB Immunoinhibition Assay

An enzymatic assay that utilizes specific antibodies against the CK-M subunit to completely inhibit both CK-MM and the M subunit of CK-MB, allowing the catalytic activity of the remaining uninhibited CK-B subunit to be quantified via a hexokinase/G6PDH coupled reaction at $340\,\text{nm}$.

Rivalta Test

A rapid qualitative bedside test adding drops of serous effusion into dilute acetic acid; formation of a distinct white, smoke-like precipitate designates an inflammatory exudate ($\text{protein} \ge 30\,\text{g/L}$), whereas clear sinking without precipitation designates a transudate ($\text{protein} < 30\,\text{g/L}$).

Hay's Sulfur Test

A qualitative urinalysis procedure for bile salts based on their capacity to lower surface tension; when dry sublimed sulfur powder is sprinkled onto the surface of urine, the powder sinks to the bottom if bile salts are present and remains floating if they are absent.