Renal Function Tests: Urea Synthesis
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Questions and Answers

What is the primary role of urea in the body?

  • To catalyze protein metabolism
  • To remove waste products from the circulation (correct)
  • To assess renal function
  • To synthesize amino acids

    • What is the term used to describe urea in the context of protein metabolism?

  • Urea acid
  • Amino acid residue
  • Urea nitrogen (correct)
  • Protein nitrogen

    • Where is urea synthesized in the body?

  • Liver (correct)
  • Pancreas
  • Spleen
  • Kidneys

    • What is the purpose of measuring urea levels in clinical chemistry?

    <p>To evaluate renal function</p> Signup and view all the answers

    What is the source of urea in the body?

    <p>Deamination of amino acids</p> Signup and view all the answers

    What is the conversion factor to convert BUN to urea?

    <p>2.14</p> Signup and view all the answers

    What does increased serum urea indicate?

    <p>Renal failure, glomerulonephritis, or urinary tract obstruction</p> Signup and view all the answers

    What is a possible reason for decreased serum urea?

    <p>Severe liver disease</p> Signup and view all the answers

    What type of disorders can cause abnormal serum urea levels?

    <p>Prerenal, renal, or postrenal disorders</p> Signup and view all the answers

    Why is the term 'blood urea nitrogen' still used?

    <p>Because it was based on previous methodology where nitrogen was measured</p> Signup and view all the answers

    What can the levels of urea indicate?

    <p>The stage of a kidney disorder</p> Signup and view all the answers

    What is a possible cause of increased serum urea?

    <p>Congestive heart failure</p> Signup and view all the answers

    What is another purpose of measuring urea levels?

    <p>To assess the patient's hydration state</p> Signup and view all the answers

    What is a possible reason for decreased serum urea?

    <p>Severe liver disease</p> Signup and view all the answers

    What is the significance of urea measurement in dialysis patients?

    <p>To assess the adequacy of dialysis</p> Signup and view all the answers

    What is the expected outcome of proper dialysis on urea levels?

    <p>A slight decrease to levels slightly higher than normal</p> Signup and view all the answers

    What is the basis of urea measurement in the blood sample?

    <p>Measurement of nitrogen levels</p> Signup and view all the answers

    What is the target range for creatinine levels after dialysis?

    <p>Slightly higher than normal</p> Signup and view all the answers

    What is the sample type used for urea measurement?

    <p>Protein-free filtrate of whole blood</p> Signup and view all the answers

    How many analytic methods are employed in the lab to determine urea levels?

    <p>At least two</p> Signup and view all the answers

    What is the product formed when urea reacts with glutamine dehydrogenase?

    <p>Glutamate + NADH + hydrogen</p> Signup and view all the answers

    What is the reference range for urea levels in the blood?

    <p>6 to 20 milligrams per dL</p> Signup and view all the answers

    What is the outcome of the reaction between diacetyl monoxime and water?

    <p>Formation of hydroxylamine and diacetyl</p> Signup and view all the answers

    What is the final product formed in the Chemical Method of urea measurement?

    <p>Yellow diazine derivative</p> Signup and view all the answers

    What is the enzyme involved in the Kinetic Method of urea measurement?

    <p>Glutamine dehydrogenase</p> Signup and view all the answers

    What is the function of urease in analytical methods?

    <p>To catalyze the hydrolysis of urea</p> Signup and view all the answers

    What specimen is susceptible to bacterial decomposition and should be refrigerated if not tested immediately?

    <p>Urine</p> Signup and view all the answers

    What is the significance of fasting in urea testing?

    <p>Fasting has a negligible effect on urea levels</p> Signup and view all the answers

    What is Azotemia?

    <p>An elevated concentration of urea in the blood</p> Signup and view all the answers

    What is the basis of urea measurement in the GDH method?

    <p>The rate of disappearance of nicotinamide adenine dinucleotide</p> Signup and view all the answers

    What is the name of the enzyme involved in the enzymatic method of urea measurement?

    <p>Urease</p> Signup and view all the answers

    What is uremic syndrome also known as?

    <p>Urea syndrome</p> Signup and view all the answers

    What is the result of reduced renal blood flow during instances like congestive heart failure?

    <p>Reduced blood flow to the kidney</p> Signup and view all the answers

    What is the consequence of less blood being filtered by the kidney?

    <p>More urea in the circulation</p> Signup and view all the answers

    What is a possible cause of prerenal disorders?

    <p>Congestive heart failure</p> Signup and view all the answers

    What is characterized by slight increases in urea levels?

    <p>Prerenal stage</p> Signup and view all the answers

    What can lead to uremic syndrome if left untreated?

    <p>Renal problems and renal failures</p> Signup and view all the answers

    What is the primary cause of increased plasma urea concentration in the renal stage?

    <p>Compromised urea excretion</p> Signup and view all the answers

    What is the term used to describe the obstruction of the urinary tract?

    <p>Postrenal Stage</p> Signup and view all the answers

    Why does the kidney become dysfunctional in chronic renal disease?

    <p>Due to the damage to the kidney's filtering ability</p> Signup and view all the answers

    What can aid in the differentiation of the cause of abnormal urea concentration?

    <p>Calculating the urea nitrogen to creatinine ratio</p> Signup and view all the answers

    What is the outcome of proper management of patients with abnormal urea concentrations?

    <p>Improved patient outcomes</p> Signup and view all the answers

    What is creatinine formed from in the body?

    <p>Phosphocreatine</p> Signup and view all the answers

    What is the primary function of measuring creatinine levels?

    <p>To determine the severity of kidney damage</p> Signup and view all the answers

    Why are creatinine levels regulated by kidney excretion?

    <p>To monitor kidney function</p> Signup and view all the answers

    What is the relationship between creatinine levels and blood urea nitrogen (BUN)?

    <p>They are directly proportional</p> Signup and view all the answers

    What happens if creatinine levels continue to rise after medication?

    <p>The medication is not effective</p> Signup and view all the answers

    What is the significance of differences in muscle mass of the sexes?

    <p>It affects creatinine levels</p> Signup and view all the answers

    What is the reactant that reacts with creatinine to form a red tautomer known as creatinine picrate in the Jaffe method?

    <p>Nitric acid</p> Signup and view all the answers

    What is the purpose of using Fuller's earth or aluminum magnesium citrate in the Jaffe reaction?

    <p>To improve the accuracy of the result</p> Signup and view all the answers

    What is the enzyme that catalyzes the reaction of creatine to yield creatine in the enzymatic method of creatinine measurement?

    <p>Creatininase</p> Signup and view all the answers

    What is the product formed when sarcosine reacts with sarcosine oxidase in the enzymatic method of creatinine measurement?

    <p>Glycine, formaldehyde, and hydrogen peroxide</p> Signup and view all the answers

    What is the final product that represents the amount of creatinine in the enzymatic method of creatinine measurement?

    <p>Water and oxidized indicator</p> Signup and view all the answers

    What is the role of peroxidase in the enzymatic method of creatinine measurement?

    <p>To oxidize the indicator</p> Signup and view all the answers

    What is plasma creatinine inversely proportional to?

    <p>Glomerular filtration rate</p> Signup and view all the answers

    Why is a 24-hour basis used for urine creatinine measurement?

    <p>Because of the endogenous result in the urinary sample</p> Signup and view all the answers

    What is not a requirement for plasma creatinine testing?

    <p>Fasting</p> Signup and view all the answers

    What can plasma creatinine be used to detect?

    <p>Kidney stones</p> Signup and view all the answers

    What is the relationship between plasma creatinine and diet?

    <p>Diet has a negligible effect on plasma creatinine levels</p> Signup and view all the answers

    What is used to estimate the glomerular filtration rate?

    <p>MDRD formula and blood creatinine</p> Signup and view all the answers

    What correction is required for estimating glomerular filtration rate?

    <p>For gender and race</p> Signup and view all the answers

    When are results of estimated glomerular filtration rate reported as a number?

    <p>Only if the result is less than 60</p> Signup and view all the answers

    What is the unit of measurement for estimated glomerular filtration rate?

    <p>Milliliters per minute per 1.73 square meters</p> Signup and view all the answers

    What is estimated by the MDRD formula?

    <p>Glomerular filtration rate</p> Signup and view all the answers

    What is characterized by an abnormal increase in plasma uric acid concentration?

    <p>Gout</p> Signup and view all the answers

    What is a possible cause of increased serum uric acid?

    <p>Renal disorders</p> Signup and view all the answers

    What is Lesch-Nyhan syndrome characterized by?

    <p>Overproduction of uric acid and neurological abnormalities</p> Signup and view all the answers

    What is a possible cause of decreased serum uric acid?

    <p>Severe liver disease</p> Signup and view all the answers

    What is an example of a condition that can cause an increase in uric acid production?

    <p>All of the above</p> Signup and view all the answers

    What is the product of the reaction between uric acid and phosphotungstic acid?

    <p>Allantoin, CO2, and tungsten blue</p> Signup and view all the answers

    What is the typical reference range for uric acid levels in males?

    <p>3.5 - 7.2 mg/dL</p> Signup and view all the answers

    What is the wavelength at which the decrease in absorbance is monitored to detect uric acid?

    <p>293 nm</p> Signup and view all the answers

    What is the enzyme that reacts with uric acid to produce allantoin, hydrogen peroxide, and CO2?

    <p>Uricase</p> Signup and view all the answers

    What is the typical reference range for uric acid levels in females?

    <p>2.6 - 6.0 mg/dL</p> Signup and view all the answers

    What is the primary role of hepatocytes in the body?

    <p>To convert ammonia to urea</p> Signup and view all the answers

    What happens when hepatocytes fail to convert ammonia to urea?

    <p>Ammonia accumulates in the blood</p> Signup and view all the answers

    What is the condition associated with high levels of ammonia in the blood?

    <p>Hyperammonemia</p> Signup and view all the answers

    What is the purpose of measuring blood ammonia levels?

    <p>To detect inherited metabolic disorders</p> Signup and view all the answers

    What type of specimen is required for measuring blood ammonia levels?

    <p>Venous blood free of hemolysis</p> Signup and view all the answers

    What is the most common cause of increased blood ammonia levels?

    <p>Severe liver disease</p> Signup and view all the answers

    What is the primary function of glutamate dehydrogenase in the measurement of ammonia?

    <p>To catalyze the reaction of alpha-ketoglutarate and ammonia</p> Signup and view all the answers

    What is the range of normal plasma ammonia levels?

    <p>11-32 μmol/L</p> Signup and view all the answers

    What is a potential interference in the measurement of ammonia?

    <p>Contamination with ammonia</p> Signup and view all the answers

    What is the wavelength used to monitor the decrease in absorbance in the measurement of ammonia?

    <p>340 nm</p> Signup and view all the answers

    What is the clinical significance of increased plasma ammonia levels?

    <p>Hepatic failure and Reye syndrome</p> Signup and view all the answers

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