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WorksheetsQuiz on Urea and Nitrogen Metabolism
Total questions: 50
Worksheet time: 25mins
Which of the following is the principal excretory product of nitrogen metabolism in humans?
Ammonia
Creatinine
Urea
Uric Acid
Non-protein nitrogenous compounds are mainly measured in the laboratory to assess:
Protein absorption
Renal function
Liver enzyme activity
Muscle contraction
Which of the following is NOT considered part of non-protein nitrogen substances?
Creatinine
Uric Acid
Urea
Albumin
Which NPN compound is neurotoxic when elevated in plasma?
Uric acid
Creatinine
Ammonia
Urea
A patient with uncontrolled elevation of NPN compounds may ultimately require:
Hydration therapy
Insulin therapy
Dialysis
Iron therapy
The first metabolite to increase in kidney disease is:
Creatinine
Uric Acid
Urea
Ammonia
Urea is synthesized in the:
Kidney
Liver
Small intestine
Pancreas
Which factor has the least effect on urea levels in blood?
Protein intake
Hydration status
Protein metabolism
Plasma glucose level
Urea excretion is approximately what percent by the kidneys?
60%
75%
90%
100%
Which conversion is correct?
Urea × 2.14 = BUN
BUN × 2.14 = Urea
BUN ÷ 2.14 = Urea
Urea × 0.357 = BUN
Azotemia refers to:
High urea in urine
High plasma urea without renal failure
Low blood nitrogen levels
Urea retention with renal failure
Uremia is best described as:
Elevated plasma ammonia
Elevated plasma urea with renal failure
Reduced urea excretion in urine only
High uric acid due to gout
Acute glomerulonephritis causing increased urea is classified as:
Pre-renal azotemia
Renal azotemia
Post-renal azotemia
Mixed azotemia
Which condition is LEAST likely to cause pre-renal azotemia?
CHF
Hemorrhage
Diabetic nephropathy
Shock
Post-renal azotemia is most likely caused by:
Polycystic kidney disease
Tumor obstruction of urinary tract
Renal tubular necrosis
Glomerulonephritis
The Fearon reaction is also known as:
Caraway Method
Diacetyl monoxime method
Berthelot’s Reaction
Jaffe’s Reaction
Nessler’s reagent produces what color end-product when reacting with ammonia?
Blue
Red
Yellow
Green
Berthelot’s reaction yields what color?
Blue
Yellow
Brown
Violet
The most frequently used enzymatic method for urea uses:
Jaffe’s Reaction
Urease-GLDH with NADH oxidation
Phosphotungstic acid
Conductimetric assay
Which method is considered the reference method for urea measurement?
Isotope Dilution Mass Spectrometry (IDMS)
Diacetyl Monoxime
Conductimetric method
Urease-NADH oxidation
Which is the most reliable index of glomerular filtration rate?
Uric acid
Creatinine clearance
BUN
Ammonia
Creatinine is derived from:
Creatine phosphate metabolism in muscle
Amino acid deamination
Purine metabolism
Pyrimidine metabolism
Creatine in urine has little diagnostic value because:
It is rapidly excreted
It is completely metabolized to creatinine
It accumulates in blood
It is not absorbed
Which is used to evaluate the completeness of 24-hour urine collection?
Creatinine excretion
Urea nitrogen
Uric acid
Cystatin C
Which is NOT true regarding creatinine?
Proportional to muscle mass
Affected by protein intake
Freely filtered by glomeruli
Not reabsorbed
The formula for creatinine clearance includes:
Plasma urea, urine urea, volume, time
Plasma creatinine, urine creatinine, volume, time
Serum uric acid, urine uric acid, time
BUN, urine volume, time
Reference range of creatinine clearance in adult males:
65–95 mL/min
85–125 mL/min
75–112 mL/min
120–150 mL/min
In creatinine clearance computation, which correction is applied?
Hematocrit
Body Surface Area (BSA)
Plasma albumin
Total protein
The estimated GFR (eGFR) formula includes correction for all EXCEPT:
Age
Gender
Race
Body mass index
A patient with creatinine clearance of 30 mL/min is classified as:
Normal
Mild renal impairment
Moderate renal impairment
Severe renal impairment
Uric acid is the end-product of metabolism of:
Pyrimidines
Proteins
Purines
Fatty acids
Which condition shows decreased uric acid concentration?
Gout
Leukemia
Chronic liver disease
Polycythemia
Which genetic disorder is associated with HGPRT deficiency?
Lesch-Nyhan Syndrome
Fanconi syndrome
Wilson’s disease
Tay-Sachs disease
A patient undergoing chemotherapy develops sudden hyperuricemia. The likely mechanism is:
Reduced excretion
Increased purine catabolism from tumor lysis
Impaired protein catabolism
Decreased liver function
Which drug inhibits xanthine oxidase to reduce uric acid formation?
Probenecid
Colchicine
Allopurinol
Sulfinpyrazone
The Caraway method uses which reagent?
Phosphotungstic acid
Diacetyl monoxime
Nessler’s salt
Jaffe’s reagent
Interference in Caraway’s method may come from:
Proteins and lipids
Urease inhibitors
Hemoglobin only
Sodium fluoride
The enzymatic method for uric acid is based on:
Uricase oxidation at 293 nm
Urease-GLDH method
Diacetyl monoxime
Conductimetry
Which anticoagulant should NOT be used for uric acid measurement?
Lithium heparin
EDTA
Sodium heparin
None of the above
Falsely decreased uric acid may occur with:
Bilirubin and hemolysis
Thiazides
Salicylates
Alcohol ingestion
Ammonia is mainly produced by:
Muscle metabolism and gut flora
Purine metabolism
Creatine breakdown
Fatty acid oxidation
The primary clinical concern with elevated plasma ammonia is:
Renal failure
Hepatic encephalopathy
Gout
Polycythemia
Ammonia concentration is normally kept low because it is:
Rapidly reabsorbed in renal tubules
Converted to urea in the liver
Converted to uric acid in the kidney
Excreted unchanged
Which of the following causes falsely increased ammonia results?
Delayed sample separation
Hemolysis
Poor refrigeration
All of the above
Which specimen is most appropriate for plasma ammonia determination?
Heparinized plasma on ice
Citrated plasma at room temperature
Serum without anticoagulant
EDTA plasma
Which of the following NPN substances is most directly related to dietary protein intake?
Uric Acid
Urea
Creatinine
Ammonia
Which NPN compound is least affected by diet?
Urea
Creatinine
Ammonia
Uric Acid
Which NPN marker is most useful in evaluating diabetic nephropathy?
Creatinine clearance
Microalbuminuria
BUN
Uric acid
Which marker is the best for early renal disease detection?
Serum creatinine
eGFR
Cystatin C
Uric Acid
A patient with joint pain, birefringent crystals in synovial fluid, and high uric acid most likely has:
Osteoarthritis
Rheumatoid arthritis
Gout
Pseudogout
