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MLSCI360 > NON-PROTEIN NITROGENOUS BIOMARKERS > Flashcards

NON-PROTEIN NITROGENOUS BIOMARKERS Flashcards

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1
Q

Ref: eGFR

A

<60 mL/ min/ 1.73 m2

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2
Q

Ref: Creatinine Clearance

A

1.30 - 2.30 mL/ sec/ 1.73 m2

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3
Q

Ref: ACR (albumin: creatinine ratio)

A

<3 mg/mmol

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4
Q

Ref: Ammonia (plasma)

A

<35 μmol/L

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5
Q

Critical: Ammonia (plasma)

A

> 199 μmol/L

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6
Q

Ref: Creatinine

A

Female: 40-100 μmol/L

Male: 50-120 μmol/L

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7
Q

Ref: Urea

A

2.5 - 8.0 mmol/L

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8
Q

Ref: Uric Acid (urate)

A

Female: 150 - 400 mol/L

Male: 200 - 500 mol/L

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9
Q

What is RAAS ?

A

Renin-Angiotensin-Aldosterone System ?
- responds to low blood pressure/ low [Na] = REABSORBS sodium and water
- kidney releases renin
- liver releases angiotensinogen
- renin converts angiotensinogen to angiotensin I
- angiotensin I converted to angiotensin II by ACE in lungs
- angiotensin II acts on adrenal gland to release aldosterone
- aldosterone promotes KIDNEY REABSORPTION OF SODIUM AND WATER

ACE = angiotensin-converting-enzymes

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10
Q

How and where is ammonia produced ?

A
  • in the liver by deamination of proteins
  • in the intestine by bacteria and endogenous enzymes
  • in renal tubular cells (from glutamine etc.)
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11
Q

Clinical Significance of increased ammonia

A
  • liver and kidney disease
  • Reye’s Syndrome (CNS disorder)
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12
Q

Specimen type for Ammonia

A
  • lithium heparin or EDTA
  • immediately on ice (4°C)
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13
Q

Interferences for Ammonia Testing

A
  • HEMOLYSIS; RBCs contain ammonia = increased
  • smoking and ethanol = increased
  • prolonged venous occlusion and fist clenching = increased
  • AMMONIUM HEPARIN = increased
  • delayed handling = increased
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14
Q

What is urea ?

A

Produced in the liver from ammonia
- freely filtered but 50% is reabsorbed in PCT

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15
Q

Clinical Significance of Increased Urea

A
  • increased protein deamination/ intake
  • increased protein catabolism from tissue breakdown and gastrointestinal bleeds
  • congestive heart failure
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16
Q

Clinical Significance of Decreased Urea

A
  • severe liver disease
  • low protein intake
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17
Q

T or F: Urea is a good indicator of renal function

A

FALSE; urea is NOT a good indicator of renal function

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18
Q

Interferences in two-step urease reaction

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A
  • HEMOLYSIS; RBCs contain ammonia = increased
  • AMMONIUM HEPARIN (forest green top) = increased
  • endogenous ammonia = increased
  • SODIUM FLOURIDE anticoagulant inhibits urease (gray top) = decreased
19
Q

What is uric acid ?

Study These Flashcards
A

Formed from oxidation of purine bases
- freely filtered, some reabsorbed by PCT

20
Q

Clinical Significance of Increased Uric Acid

Study These Flashcards
A

Hyperuricemia:
- chronic renal failure; decreased excretion
- chemotherapy
- thiazide diuretics
- hypertension

21
Q

Clinical Significance of Decreased Uric Acid

Study These Flashcards
A

Hypouricemia = Fanconi’s Syndrome (loss of uric acid in PCT), decreased liver enzymes required for depurination

22
Q

Interferences in two-step uric acid (uricase) reaction

Study These Flashcards
A
  • SODIUM FLOURIDE anticoagulant (gray top) = increased
  • salicylates = increased
  • bilirubin = decreased
  • ascorbic acid/ vit C = decreased
  • hemolysis = decreased
23
Q

What is creatinine ?

Study These Flashcards
A
  • formed from creatine in skeletal muscle
  • freely filtered
  • dependant on muscle mass (higher in males)
  • little change in response to diet
24
Q

Clinical Significance of Increased vs Decreased Creatinine

Study These Flashcards
A
  • used to estimate glomerular filtration rate

Increased = decreased GFR

Decreased = muscular dystrophy; inadequate conversion of creatine

25
What does creatinine clearance test for ?
Glomerular function
26
Sample Requirements for Creatinine Clearance
- blood sample drawn within 72 hours of urine collection - 24 hour urine collection must be refrigerated
27
Creatinine Clearance Formula
C (mL/s) = (UV/P) x (1.73/SA) where, U = urine creatinine concentration (μmol/L) V = volume of urine (mL/ sec OR mL/ min) P = plasma creatinine concentration (μmol/L) SA = of patient, calculated using height and weight
28
How many seconds in 24 hours ?
24 hours = 86,400 seconds
29
Why does the creatinine clearance test overestimates GFR ?
~10% of creatinine in urine is due to tubular secretion
30
Creatinine clearance is __ in renal disease.
Creatinine clearance is DECREASED in renal disease.
31
Why is eGFR useful ?
estimates GFR WITHOUT a 24 URINE COLLECTION
32
In what cases is eGFR not applicable ?
- acute kidney injury - abnormal muscle mass - medication ie. salicylates, furosemide
33
Albuminuria is a marker for __.
Abuminuria is a marker for CHRONIC KIDNEY DISEASE.
34
Proteinuria due to low MW globulins is a marker for __.
Proteinuria due to low MW globulins is a marker for TUBULAR DAMAGE.
35
What is ACR used for ?
Albumin:Creatinine Ratio is used to overcome diurnal variation of albumin/ hydration
36
How many positive ACR results are required to diagnose chronic kidney disease (CKD) ? What is used to monitor CKD ?
- 2 or more positive ACR results to diagnose - ACR is also used for monitoring
37
What small peptide is a good indicator of GFR ? Why ?
β-microglobulin: - freely filtered by glomerulus - unaffected by muscle mass and diet - increased in renal failure and malignancies
38
Causes of pre-renal Acute Kidney Injury (AKI)
- decreased circulating blood supply (hypovolemia) - cardiac failure - burns, hemorrhage, vomiting, diarrhea, sepsis
39
Causes of renal Acute Kidney Injury (AKI) ?
- vascular, glomerular, interstitial damage - myoglobinuria - heavy metal poisoning
40
Causes of post-renal Acute Kidney Injury (AKI) ?
- obstruction of flow of urine after kidney - prostatic enlargement, renal stones, fibrosis, neoplasms
41
What does isosthenuria indicate in CKD ?
- SG is the SAME as protein-free plasma - kidney’s lack of concentrating ability
42
What is the primary cause of CKD ?
Diabetes mellitus > hypertension > glomerular nephritis
43
Creatinine is measured by the __ reaction.
Creatinine is measured by the JAFFE KINETIC reaction.
44
Interferences in the Jaffe Kinetic reaction
- ketones, ascorbate, cephalosporin, glucose, proteins = increased - bilirubin and HEMOGLOBIN = decreased NOTE: jaffe kinetic reaction is used to measure creatinine

MLSCI360 (22 decks)

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