CLINICAL CHEMISTRY I - ANALYTE HANDBOOK

This set contains 250 practice vocabulary flashcards for Clinical Chemistry I based on the provided lecture handbook.

Kidney Acid-Base Balance Function

The excretion of excess acid or alkali from the body.

Normal Urine pH Range

$$4.5 - 8.0$$

Average Urine pH Acidity

Slightly acidic due to normal metabolic acid production.

Alkaline Tide

A temporary increase in urine pH after meals caused by parietal cells extracting $Cl^-$ from plasma to produce $HCl$, releasing $HCO_3^-$ into the plasma.

Urine pH Reagent Strip Indicators

Methyl red and Bromothymol blue.

Effect of Bacterial Proliferation on Urine pH

Increases pH due to the conversion of urea to ammonia.

pH Pad False Decrease Cause

Acid buffer from the protein pad contaminating the pH pad.

Urine Specific Gravity (SG) Definition

A measure of the density of urine compared with water, reflecting the concentration of solutes.

Reference ranges for Urine SG

$$1.005 - 1.030$$

Lowest Physiologically Possible Urine SG

Approximately $1.002$

Highest Physiologically Possible Urine SG

Approximately $1.040$

Urine SG Refractometry Mechanism

Measures refraction of light passing through urine, which depends on wavelength, temperature, and solute concentration.

SG Refractometer Distilled Water Calibration

$$1.000$$

SG Refractometer 3% NaCl Calibration

$$1.015$$

SG Refractometer 5% NaCl Calibration

$$1.022$$

SG Reagent Strip Chemical Principle

Based on a colorimetric reaction measuring ionic solutes where a polyelectrolyte releases $H^+$ in the presence of ions.

Non-ionic Solutes Not Measured by SG Strip

Urea, glucose, creatinine, and proteins.

Manual SG Reagent Strip pH Correction

Add $0.005$ if the pH is $\ge 6.5$.

Hematuria

The presence of intact RBCs in urine, often causing varying degrees of cloudiness.

Hemoglobinuria

The presence of hemoglobin in urine, which appears clear but colored.

Factors Enhancing RBC Lysis in Urine

Alkaline urine and dilute urine ($SG \le 1.010$).

Haptoglobin

A plasma protein that binds free hemoglobin to prevent its filtration by the glomeruli.

Hemosiderin

An iron-storage complex found in urine as free granules, in casts, or in RTE cells after hemoglobin reabsorption.

Hemosiderin Identification Stain

Prussian blue stain.

Myoglobin

A heme protein abundant in muscle used for oxygen transport.

Myoglobinuria Causes

Major trauma, crush injury, myositis, medication-induced myopathy, or seizures.

Urine Blood Pad Chemical Principle

Based on the peroxidase-like activity of heme, which breaks down $H_2O_2$, causing oxidation of a chromogen.

Blood Pad Appearance: Green Specks

Indicates the presence of intact RBCs.

Blood Pad Appearance: Uniform Green

Indicates the presence of hemoglobin or myoglobin.

Microbial Peroxidases (Blood Pad)

A source of false positive results in the blood reagent pad.

Ascorbic Acid (Blood Pad)

A source of false negative results for the blood pad.

Leukocyturia (Pyuria)

Increased numbers of WBCs in urine, indicating infection or inflammation.

Urine Leukocyte Reagent Pad Principle

Esterase enzymes in granulocytes cleave an ester to produce an aromatic compound that reacts with diazonium salt to form purple azo dye.

Cells Detected by Leukocyte Esterase Pad

Granulocytic WBCs including neutrophils, eosinophils, and basophils.

WBC Type Not Detected by Leukocyte Pad

Lymphocytes.

Beeturia (Leukocyte Pad)

Highly colored urine that can cause false positive leukocyte results.

Glucosuria

The presence of glucose in urine.

Glycosuria

The presence of non-glucose sugars in urine.

Renal Threshold for Glucose

$$10.0\,mmol/L$$

Fanconi’s Syndrome (Glucose)

A condition with defective tubular reabsorption leading to glucosuria with normoglycemia.

Glucose Oxidase Method Specificity

Specific for glucose; no other sugars give positive results.

Bleach (Urine Glucose)

Acts on the chromogen and oxidizes it, causing a false positive.

Ascorbic Acid (Urine Glucose)

A reducing agent that decreases the amount of glucose detected, causing a false negative.

Ketone bodies Proportion in Ketonuria

$\beta$-hydroxybutyrate ($78\%$), Acetoacetate ($20\%$), and Acetone ($2\%$).

Ketone Nitroprusside Reaction

Acetoacetate reacts with nitroprusside in an alkaline medium to produce a color change.

Multistix Ketone Pad Specificity

Detects acetoacetate only.

Chemstrip Ketone Pad Specificity

Contains glycine to detect both acetoacetate and acetone.

Nitrite Screening Test Purpose

Screening test for Urinary Tract Infection (UTI).

Nitrate Reductase

An enzyme produced by many bacteria (e.g., E. coli) that converts dietary nitrates to nitrites in the bladder.

Nitrite Reagent Pad Principle

Nitrites react with an aromatic amine to form a diazonium salt, which then reacts with another aromatic compound to produce a pink azo dye.

Normal Urinary Protein Excretion

Up to $150\,mg/day$

Uromodulin (Tamm-Horsfall protein)

A mucoprotein from distal tubular cells that regulates sodium transport and protects from UTIs.

Urokinase

A fibrinolytic enzyme produced by renal tubular epithelial cells.

Microalbuminuria Excretion Range

$$30 - 300\,mg/day$$

Protein-error-of-indicators Principle

The ability of protein to change the color of a pH indicator (e.g., tetrabromphenol blue) while the pH is held constant.

Highly Alkaline Urine (Protein Pad)

Urine with $pH \ge 9.0$ can cause a false positive protein result.

Creatinine

The end-product of creatine metabolism and a nitrogenous waste product excreted in urine.

Creatinine Specimen Requirements

Serum or heparinized plasma separated from RBCs promptly to minimize in vitro ammonia production.

Creatine Precursors

Glycine, Arginine, and Methionine.

Phosphocreatine

A high-energy compound that serves as an energy reserve in muscle by donating phosphate to convert ADP to ATP.

Creatine Kinase (CK)

The enzyme that catalyzes the phosphorylation of creatine to phosphocreatine.

Daily Creatine to Creatinine Conversion

$1 - 2\%$ of creatine is spontaneously and irreversibly converted to creatinine daily.

Renal Handling of Creatinine

Freely filtered by the glomerulus and not reabsorbed, with a small amount of tubular secretion.

Jaffe Reaction Principle

Creatinine reacts with alkaline picrate to form a colored complex measured at $520\,nm$.

Non-creatinine Chromogens (Jaffe Reaction)

Ascorbic acid, glucose, ketone bodies, protein, pyruvate, and cephalosporins.

Creatinine Kinetic Assay Window

The change in absorbance is measured between $20$ and $80$ seconds to minimize interference from fast and slow-reacting chromogens.

Bilirubin Interference in Jaffe Reaction

Bilirubin is oxidized in alkaline medium to a colorless compound, falsely decreasing the creatinine concentration.

Creatininase Method (Enzymatic)

Monitors the disappearance of NADH at $340\,nm$, where absorbance decrease is proportional to creatinine concentration.

Urea Origin

Formed in the liver from protein metabolism via the urea cycle to handle toxic ammonia ($NH_3$).

Azotemia

An increased concentration of urea (nitrogen) in the blood.

BUN (Blood Urea Nitrogen)

The amount of urea nitrogen expressed in $mg/dL$; common in the US.

Urea to BUN Conversion

Urea values are approximately $2 \times$ the BUN values because nitrogen accounts for about half the MW of urea ($~60\,g/mol$).

Berthelot Reaction

A colorimetric method where ammonia reacts to form indophenol blue, with nitroprusside as a catalyst, measured at $560\,nm$.

Urease:GLDH Method

A coupled enzymatic reaction where urease produces $NH_4^+$ which is used by glutamate dehydrogenase to convert NADH to NAD+ ($340\,nm$).

Effect of Fluoride/Citrate on Urease

These anticoagulants inhibit the urease reaction.

Plasma Urea Reference Range (>18 years)

$$2.5 - 8.0\,mmol/L$$

Uric Acid

A non-protein nitrogen compound produced as the end-product of purine catabolism.

Xanthine

An intermediate in the purine catabolism pathway that is oxidized to uric acid in the liver.

Uricase

An enzyme humans lack, which would normally convert uric acid to allantoin.

Lesch-Nyhan Syndrome

An X-linked recessive disorder caused by a complete deficiency of HGPRT, resulting in severe hyperuricemia and self-injury behavior.

Gout

A condition where monosodium urate monohydrate crystals precipitate in joints and tissues from supersaturated body fluids.

Pseudogout

Condition caused by the deposition of calcium pyrophosphate crystals, mimicking gout.

Uric Acid Analytical Methodology

Uric acid is oxidized to allantoin and $H_2O_2$; $H_2O_2$ then reacts with a chromogen and peroxidase to produce color.

Uric Acid Reference Range (Males)

$$180 - 500\,\mu mol/L$$

Uric Acid Reference Range (Females)

$$150 - 400\,\mu mol/L$$

Glycolysis (Embden-Meyerhof pathway)

The anaerobic metabolism of glucose where each molecule produces a net of $2$ ATP and $2$ Pyruvate.

Lactic Acid Fermentation

The conversion of pyruvate to lactate under anaerobic conditions, catalyzed by lactate dehydrogenase.

Citric Acid Cycle (CAC) Location

Occurs in the mitochondria.

ATP Yield per Acetyl CoA in CAC

$1$ ATP, $3$ NADH, and $1$ $FADH_2$.

Total ATP Yield from Aerobic Glucose Metabolism

Net total of $36$ ATP (adjusted for transport costs).

Oxidative Phosphorylation

The combination of the electron transport chain and chemiosmosis to produce ATP.

Pentose Phosphate Pathway Products

NADPH, Ribose-5-phosphate, and Erythrose-4-phosphate.

Glycogenesis

The synthesis of glycogen from glucose, occurring mainly in the liver and muscles.

Lipogenesis

The synthesis of lipids from excess glucose.

Carbohydrate Stoichiometric Formula

$(CH_2O)_n$ where $n > 3$

Monosaccharide Definition

The simplest form of carbohydrate that cannot be hydrolyzed further.

Disaccharide Definition

Two monosaccharides joined by an O-glycosidic bond.

Maltose Components

Glucose + Glucose

Lactose Components

Glucose + Galactose

Sucrose Components

Glucose + Fructose