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CC1 > Lec 11: NPN > Flashcards

Lec 11: NPN Flashcards

1
Q

What are the clinically significant NPN compounds?

A

• Urea
• Amino acids
• Uric acid
• Creatinine
• Creatine
• Ammonia

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2
Q

UREA

Plasma conc: ___
Urine conc: ___

A

Plasma conc: 45-50
Urine conc: 86

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3
Q

URIC ACID

Plasma conc: ___
Urine conc: ___

A

Plasma conc: 10
Urine conc: 1.7

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4
Q

CREATININE

Plasma conc: ___
Urine conc: ___

A

Plasma conc: 5
Urine conc: 4.5

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5
Q

AMMONIA

Plasma conc: ___
Urine conc: ___

A

Plasma conc: 0.2
Urine conc: 2.8

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6
Q

AMINO ACID

Plasma conc: ___

A

Plasma conc: 25

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7
Q

CREATINE

Plasma conc: ___

A

Plasma conc: 1 to 2

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8
Q

The most abundant waste product in the body. It has the highest concentration in the plasma and urine.

A

Urea

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9
Q

The major excretory product of protein metabolism.

A

Urea

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10
Q

Where does the Urea Cycle occur?

A

Hepatocytes/Liver cells

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11
Q

Its goal is to convert ammonia into a less toxic urea. It’s an important pathway to reduce levels of ammonia in the blood

A

Urea cycle

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12
Q

UREA

Chemical method: ___
Enzymatic method: ___

A

Chemical method:
• Diacetyl monoxime

Enzymatic method:
• Urease
• Coupled Urease with GLDH

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13
Q

Color result of DAM

A

Yellow

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14
Q

Wavelength used in DAM method

A

540 nm

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15
Q

In enzymatic method using urease, what product was quantified?

A

Ammonia or Ammonium ion

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16
Q

Coupled urease with GLDH is also known as ___

A

Berthelot method

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17
Q

In coupled urease with GLDH, what was the wavelength used?

A

340 nm

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18
Q

The reference method (gold standard) for urea, uric acid, and creatinine.

A

IDMS

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19
Q

Conversion factor:
BUN mg/dL to urea mg/dL

A

2.14

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20
Q

Conversion factor:
BUN mg/dL to Urea mmol/L

21
Q

False negative or positive?

In Urea, using sodium citrate & sodium fluoride as anticoagulant.

A

NEGATIVE

• it inhibits urease

22
Q

False negative or positive?

In Urea, using hemolyzed samples.

A

POSITIVE

• RBCs contain urea inside

23
Q

False negative or positive?

In Urea, using samples contaminated with bacteria.

A

NEGATIVE

• Bacteria produce their own urease and will convert urea on their own.

24
Q

When collecting plasma samples for UREA, what anticoagulants are AVOIDED and USED?

A

MAY USE:
lithium & sodium heparin

AVOID:
Sodium citrate & sodium fluoride
- inhibits urease
- false negative
ammonium heparin
- false positive

25
Q

UREA
reference ranges

A

6–20 mg/dL
2.1–7.1 mmol/L

26
Q

Prerenal azotemia

A

Increase of plasma urea as a result of reduced renal blood flow, which is caused before the kidney.

27
Q

Postrenal azotemia

A

Increase of urea concentration in the plasma due to obstruction of urine flow, which occurs after the kidney.

28
Q

Low protein intake & severe liver disease can cause major _____ in plasma urea concentration.

(Increase or Decrease)

29
Q

URIC ACID is a final product of _____

A

Catabolism of purine nucleic acids

30
Q

Uric acid is the major product of catabolism of what purine nucleosides?

A

Adenosine, Guanosine

31
Q

Approximately ___% of Uric acid excreted is lost in the urine. While proximal tubules reabsorb ___% of uric acid.

A

70%
98–100%

32
Q

Uric acid is ___ in urine, while it is ___ in the blood.

(Soluble, insoluble)

A

pKa of Uric acid: 5.75

Urine: insoluble
- urine pH is near 5.75

Blood: soluble
- blood pH is 7.35–7.45

33
Q

Nearly all Uric acid in plasma is present as ___.

A

Monosodium
urate

34
Q
  1. Define Hyperuricemia.
  2. Causes
A
  1. Increase uric acid in blood.
  2. Excess dietary purine intake, chemotherapy
35
Q

Define Hyperuricosuria.

A

Increase of uric acid in urine

36
Q

URIC ACID

  1. Chemical method
    • color result
  2. Enzymatic method
    • give the wavelength used
A
  1. Phosphotungstic acid (caraway method)
    • tungsten blue
  2. Uricase, couple uricase with peroxidase/catalase
    • 293 nm, 548 nm
37
Q

Abnormally increased plasma uric acid concentration is seen in ____ wherein there is:
• crystallization of uric acid (sodium urate)
• found primarily in men
• commonly affects big toe
• in women, rises after menopause

38
Q

The following causes what NPN compound to increase?
• hemolytic/megaloblastic anemia
• starvation
• chemotherapy
• purine-rich diet

39
Q

An X-linked genetic disorder caused by deficiency of hypoxanthine-guanine phosphoribosyltransferase. Seen ONLY in males.

A

Lesch-Nyhan Syndrome

40
Q

False negative or positive?

In uric acid, using hemolyzed samples.

A

NEGATIVE
• when RBCs burst, it causes serum dilution.

41
Q

False negative or positive?

In uric acid, using samples with high bilirubin concentration.

42
Q

What drugs increase values for Uric Acid?

A

Salicylates, Thiazides

43
Q

When collecting plasma samples for Uric Acid:

  1. what anticoagulants are AVOIDED?
  2. False negative or positive?
A
  1. EDTA, fluoride additives
    • inhibit uricase
  2. NEGATIVE
44
Q

What causes decrease in Plasma Uric Acid concentration?

A

• liver decease
• allopurinol over treatment
• Fanconi syndrome
- defective tubular reabsorption causes ALL URIC ACID to go to urine, and nothing to the blood.

45
Q
  • Formed from creatine and creatine phosphate.
  • excreted at a constant rate.
A

Creatinine

46
Q

Plasma creatinine is ____ proportional to Glomerular Filtration Rate.

A

Inversely.
• kidney working well = more filtration = low plasma creatinine

47
Q
  1. Immediate precursor of creatinine?
  2. Based on #1’s answer, from what organs is it synthesized?
  3. After synthesis, where is it transported to?
A
  1. Creatine
  2. Liver, pancreas, kidney
  3. Muscles
48
Q

CREATININE

  1. Chemical method
    • color result
    • wavelength used
    • interferences
  2. Enzymatic method
A
  1. Jaffe’s method (alkaline picrate sol)
    • red orange chromogen (Janovski complex)
    • 490–505 nm
    • acetoacetate, glucose, acetone, pyruvate, ascorbate
  2. Creatininase-Hydrogen Peroxide, Creatininase-Creatine Kinase
49
Q

CREATININE

  1. What anticoagulants are USED?
  2. What KIND of samples are AVOIDED?
A
  1. Sodium & lithium heparin
  2. Icteric, hemolyzed, lipemic
    • false negative

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