Kidney Function Tests Vocabulary Flashcards

100 vocabulary flashcards reviewing key concepts, methods, formulas, normal values, and conditions from the Kidney Function Tests lecture transcript.

Glomerular filtration

The first step in urine formation occurring in the glomerulus.

Tubular secretion

The second step in urine formation where substances are secreted into the renal tubules.

Tubular reabsorption

The third step in urine formation where solutes and water are reabsorbed back into the bloodstream.

Glomerulus

The renal structure surrounded by Bowman's capsule responsible for blood filtration.

Proximal Convoluted Tubule (PCT)

The initial segment of the nephron tubule leading from Bowman's capsule.

Loop of Henle

The U-shaped loop of the nephron tubule that functions in urine concentration.

Distal Convoluted Tubule (DCT)

The segment of the nephron tubule following the Loop of Henle.

Collecting ducts

The final tubular structures in nephrons that collect urine and pass it toward the renal pelvis.

GFR (Glomerular Filtration Rate)

A measure of renal filtration capacity calculated using the clearance formula $\text{GFR} = \frac{U \times V}{P}$.

Urea clearance test

A GFR clearance test with a normal reference value of $75\,\text{ml/min}$.

Creatinine clearance test

A GFR clearance test with a normal reference value of $70\text{--}157\,\text{ml/min}$.

Inulin clearance test

An exogenous clearance test measuring GFR with a normal reference value of $120\,\text{ml/min}$.

Iothalamate clearance test

A GFR clearance test using iothalamate, having a normal value of $120\,\text{ml/min}$.

Standard clearance formula

Formula expressed as $\text{Std. clearance (ml/min)} = \frac{U (\text{mg/dl}) \times V (\text{ml/min})}{P (\text{mg/dl})} \times \frac{1.73}{A}$.

Total Nonprotein Nitrogenous (TNPN)

A category of nitrogen-containing metabolic waste products used in tests measuring RPF.

Kjeldahl technique

A digestion process used in total nonprotein nitrogenous (TNPN) determination.

Nesslerization

A chemical method measuring ammonia ($\text{NH}_3$) in NPN and indirect urea determination.

Berthelot reaction

An indophenol test method used for the quantification of ammonia in urea and NPN assays.

TNPN serum reference range

The normal reference value of total nonprotein nitrogen in serum, equal to $20\text{--}35\,\text{mg/dL}$.

TNPN whole blood reference range

The normal reference value of total nonprotein nitrogen in whole blood, equal to $25\text{--}50\,\text{mg/dL}$.

Azotemia

The accumulation of nonprotein nitrogenous substances (NPNs) in the blood.

Prerenal azotemia

Azotemia seen in congestive heart failure, hemorrhage, and increased protein catabolism.

Renal azotemia

Azotemia seen in acute glomerulonephritis and tubular necrosis.

Postrenal azotemia

Azotemia seen in urolithiasis, prostatic enlargement, and tumors in the urinary tract.

BUN (Blood Urea Nitrogen)

The major catabolic product of proteins, formed in the liver from ammonia and carbon dioxide.

BUN to Urea conversion formula

Formula expressed as $\text{BUN (mg/dl)} \times 2.14 = \text{Urea (mg/dl)}$.

Urea to BUN conversion formula

Formula expressed as $\text{Urea (mg/dl)} \times 0.467 = \text{BUN (mg/dl)}$.

BUN normal reference range

The normal blood urea nitrogen concentration of $10\text{--}20\,\text{mg/dl}$ ($2.5\text{--}6.4\,\text{mmol/L}$).

BUN conversion factor

The factor used to convert BUN values, equal to $0.357$.

Fearon (DAM) method

A direct method of urea determination where diacetyl monoxime hydrolyzes to diacetyl and forms a yellow diazine product measured at $550\,\text{nm}$.

Xanthydral method

A direct urea determination method where urea directly reacts with xanthydral to form yellow dixanthydral urea measured spectrophotometrically.

Xanthom

A root word meaning yellow.

Urease

An enzyme used in indirect methods to hydrolyze urea into carbon dioxide and ammonia.

Folin-Svedberg method

An indirect method of urea determination based on ammonia formation following urease action.

Modified Kaar method

An indirect method of urea determination following urease hydrolysis.

Gentzkow-Massen method

An indirect technique for urea quantification based on measurement of ammonia.

Urograph (strip test)

A strip-testing indirect method for urea determination.

Van Slyke – Cullen method

An indirect urea measurement method involving urease hydrolysis of urea.

Glutaric dehydrogenase method

An enzymatic indirect urea method measuring NADH consumption according to $\text{NH}_3 + \alpha\text{-ketoglutarate} + \text{NADH} \rightarrow \text{glutamate} + \text{NH}_4^+ + \text{NAD}$.

Conductivity Rate Measurement

A method used in semiautomated Beckman analyzer measuring the conductivity of a mixture of ammonium and bicarbonate ions.

ISE Ammonium Sensing Electrode

An ion-selective electrode method used to detect ammonium ions in indirect urea assays.

Creatinine

An anhydrous form of creatine and waste product of muscle metabolism synthesized from glycine, methionine, and arginine, considered the best index for renal function.

Creatinine normal reference range

The normal concentration of creatinine in serum, equal to $0.6\text{--}1.2\,\text{mg/dl}$ ($53\text{--}106\,\mu\text{mol/L}$).

Creatinine conversion factor

The factor used to convert creatinine from $\text{mg/dl}$ to $\mu\text{mol/L}$, equal to $88.4$.

Jaffe reaction

A direct creatinine method where creatinine reacts with fresh alkaline picrate ($1:6$, $10\%\,\text{NaOH}\text{-picrate}$) to form a red-orange 1:1 Janovsky complex.

Janovsky complex

The red-orange 1:1 chromogen complex formed between creatinine and alkaline picrate in the Jaffe reaction.

Folin-Wu method for creatinine

A Jaffe reaction method that requires deproteinization.

Lloyd's method

The reference Jaffe method employing an adsorbing agent, Lloyd's reagent.

Lloyd's reagent

Hydrated aluminum silicate used as an adsorbing agent in Lloyd's reference method for creatinine quantitation.

Fuller's Earth method

A Jaffe reaction method that uses Fuller's earth or floridin as an adsorbent.

3,5 - Dinitrobenzoic Acid (DNBA) method

A direct creatinine method forming a purplish-rose product used in endpoint dry strip testing.

Creatinase (CAH)

Creatine amidohydrolase, an enzyme that converts creatinine to creatine in indirect multienzymatic approaches.

CAH-CK-PK-LDH approach

A multienzyme indirect creatinine method utilizing Creatinase, Creatine Kinase, Pyruvate Kinase, and Lactate Dehydrogenase.

Creatinine Iminohydrolase (CIH) method

An indirect method converting creatinine to N-methylhydantoin and $\text{NH}_3$, coupled with glutamate dehydrogenase.

Blood Uric Acid (BUA)

The major end product of purine catabolism formed directly from xanthine in the presence of xanthine oxidase.

Xanthine oxidase

The enzyme responsible for directly converting xanthine into uric acid.

APRT

Adenine phosphoribosyltransferase, one of two key enzymes required in purine metabolic pathways associated with BUA.

HGPRT

Hypoxanthine guanine phosphoribosyl transferase, an enzyme involved in purine salvage.

Male BUA normal reference range

The normal blood uric acid concentration in males, equal to $4.0\text{--}8.5\,\text{mg/dl}$ ($0.24\text{--}0.51\,\text{mM}$).

Female BUA normal reference range

The normal blood uric acid concentration in females, equal to $2.7\text{--}7.3\,\text{mg/dl}$ ($0.16\text{--}0.43\,\text{mM}$).

BUA conversion factor

The factor used to convert uric acid from $\text{mg/dl}$ to $\text{mmol/L}$, equal to $0.059$.

Phosphotungstic acid (PTA) reduction

A direct redox method where uric acid reduces PTA in an alkaline solution to form allantoin, carbon dioxide, and tungsten blue.

Tungsten blue

The blue chromogen formed when uric acid reduces phosphotungstic acid in direct redox methods.

NaCN alkalinizing adaptations

Direct redox phosphotungstic acid methods using sodium cyanide as alkalinizing agent, including Folin, Brown, Benedict, and Newton.

Sodium carbonate alkalinizing adaptations

Direct redox phosphotungstic acid methods using sodium carbonate as alkalinizing agent, including Caraway, Archibald, and Henry.

Caraway method

A direct redox uric acid determination method using sodium carbonate as the alkalinizing agent.

Archibald method

A direct redox method for uric acid quantitation using sodium carbonate as an alkalinizing agent.

Henry method

A direct redox uric acid measurement method employing sodium carbonate as an alkalinizing agent.

Uricase

An enzyme used in indirect uric acid methods catalyzing $\text{UA} + \text{H}_2\text{O} + \text{O}_2 \rightarrow \text{allantoin} + \text{CO}_2 + \text{H}_2\text{O}_2$.

Blaunch and Koch method

An indirect method measuring differential UV absorption of UA at $290\text{--}293\,\text{nm}$ and allantoin, resulting in a decrease in absorbance.

Coupled uricase method

An indirect uric acid method where peroxide formed after uricase hydrolysis reacts with PAP, o-dianisidine, or dimethyl aniline.

Uricase-Hantzsch method

An indirect uric acid method where produced peroxide is oxidized to formaldehyde by catalase and proceeds to dihydrolutidine measurement.

Polarographic uricase method

An indirect uric acid method where oxygen consumed during the uricase reaction is measured using an electrode.

Dye excretion tests

Tests measuring tubular excretion functions, commonly using phenolsulfonphthalein (PSP).

Phenolsulfonphthalein (PSP)

A dye used in excretion tests for tubular function with a normal reference value of $60\text{--}86\%$ excretion in 2 hours.

PAH test for ERPF

A clearance test using p-aminohippurate (PAH) to measure Effective Renal Plasma Flow.

RPF formula

Formula expressed as $\text{RPF (ml/min)} = \frac{U_{\text{PAH}} \times V (\text{ml/min})}{P_{\text{PAH}}}$.

PAH test normal value

The normal reference value for effective renal plasma flow, equal to $600\text{--}700\,\text{ml/min}$.

Random urine Specific Gravity reference range

The normal specific gravity of a random urine sample, equal to $1.003\text{--}1.035$.

24 Hr urine Specific Gravity reference range

The normal specific gravity of a 24-hour urine sample, equal to $1.015\text{--}1.025$.

Serum Specific Gravity reference range

The normal specific gravity of serum, equal to $1.010\text{--}1.012$.

Osmolality

The best test to determine maximal concentration and dilution of urine, with normal value $>285\text{--}319\,\text{mOsmol/kg H}_2\text{O}$.

Serum osmolality formula

Formula expressed as $\text{serum osmol} = 1.86\,\text{Na} + \frac{\text{glucose}}{18} + \frac{\text{BUN}}{2.8}$ or $2\,\text{Na} + \frac{\text{glucose}}{20} + \frac{\text{BUN}}{3}$.

U/S Osmol ratio

Urine to serum osmolality ratio used to differentiate between etiologies of polyuria.

Water diuresis

An etiology of polyuria characterized by a U/S Osmol ratio of $<1$.

Osmotic diuresis

An etiology of polyuria characterized by a U/S Osmol ratio of $>1$.

Free water clearance

A test measuring kidney concentration and dilution ability calculated as $C_{\text{water}} = V - C_{\text{osmol}}$.

Positive water clearance

A free water clearance result indicating that urine is more dilute relative to serum.

RFI (Renal Failure Index)

An index used with FeNa to distinguish pre-renal from renal acute renal failure, calculated as $\text{RFI} = \frac{U_{\text{Na}}}{U_{\text{crea}} / P_{\text{crea}}}$.

FeNa (Fractional Excretion of Sodium)

A calculation used to classify acute renal failure, expressed as $\text{FeNa} = \frac{U_{\text{Na}} \times P_{\text{crea}} \times 100}{U_{\text{crea}} \times P_{\text{Na}}}$.

Fishberg concentration test

A concentration test evaluating the ability of renal tubules to concentrate urine.

Allopurinol

A medication that decreases uric acid production, leading to lowered serum levels.

BUN/Creatinine ratio reference range

The normal reference range for the ratio of BUN to creatinine, equal to $12\text{ to }20$.

Low BUN/Creatinine ratio

A ratio $<12$ seen in hepatic disease/failure, low protein diet/starvation, and acute tubular necrosis.

High BUN/Creatinine ratio with normal creatinine

A ratio $>20$ with normal creatinine seen in prerenal uremia, high protein diet, GI hemorrhage, and catabolic states.

High BUN/Creatinine ratio with high creatinine

A ratio $>20$ with elevated creatinine seen in prerenal azotemia with renal disease, renal failure, and postrenal azotemia.

Pre-renal causes of uremia

Conditions leading to reduced blood flow to the kidney (shock, blood loss, dehydration) or increased protein catabolism (crush injuries, burns, fever, hemorrhage, hemolysis).

Acute renal causes of uremia

Conditions causing acute renal failure, such as glomerulonephritis, malignant hypertension, nephrotoxic drugs/metals, and renal cortical necrosis.

Chronic renal causes of uremia

Chronic kidney diseases including pyelonephritis, diabetes mellitus, arteriosclerosis, amyloidosis, renal tubular disease, and collagen-vascular disease.

Post-renal causes of uremia

Urinary outflow obstructions including ureteral obstruction by stones, tumor, inflammation, surgical misadventure, or obstruction of bladder neck/urethra.