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Mercy CLS 5: Chemistry > 11) Nonprotein nitrogen and renal function > Flashcards

11) Nonprotein nitrogen and renal function Flashcards

1
Q

urinary filtrate flow

A

Bowman’s capsule
Proximal convoluted tubule (PCT)
Descending loop of Henle
Ascending loop of Henle
Distal convoluted tubule (DCT)
Collecting duct
Renal calyces
Ureter
Bladder
Urethra

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2
Q

renal blood flow

A

Renal artery
Afferent arteriole
Glomerulus
Efferent arteriole
Peritubular capillaries
Vasa recta
Renal vein

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3
Q

large, ——- charged molecules are repelled by the —– charge of the basement membrane

A

negatively
negative

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4
Q

renal threshold

A

Concentration above which the substance cannot be totally reabsorbed and is excreted in the urine

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5
Q

always reabsorbed through passive transport

A

water
urea

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6
Q

2 major functions of tubular secretion

A
  • Elimination of waste products not filtered by the glomerulus
  • Regulation of acid-base balance in the body through secretion of H+
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7
Q

nonprotein nitrogen

A

Comprises the products of catabolism of proteins and nucleic acids, which contain nitrogen but are not part of a protein molecule

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8
Q

most clinically significant NPN in plasma

A

BUN
amino acids
uric acid
creatinine
creatine
ammonia

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9
Q

3 NPN sources in highest amount

A

Blood urea nitrogen (BUN)
Amino acids
Uric acid

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10
Q

Major nitrogen-containing metabolic product of protein catabolism in humans

A

urea/BUN

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11
Q

Approximately —% of NPN is eventually excreted

A

75

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12
Q

In a patient with a normal to increased GFR, approximately –% of the BUN is reabsorbed and –% is excreted.

A

40
60

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13
Q

In a dehydrated patient, –% of the BUN is reabsorbed and –% is excreted.

A

70
30

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14
Q

3 variables BUN depends on

A

Urea concentration
Glomerular filtration rate
Level of hydration

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15
Q

azotemia

A
  • An increased blood urea and other NPN compounds
  • No external symptoms
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16
Q

uremia

A
  • An increased BUN
  • More severe, now showing sx (n/v, fatigue, HTN, anorexia, uremic frost)
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17
Q
A

uremic frost

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18
Q

3 categories of azotemia

A

prerenal
renal
postrenal

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19
Q

normal BUN:creatinine ratio

A

10:1 to 20:1

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20
Q

normal BUN:Cr ratio

A

renal disease
elevated proportionally

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21
Q

prerenal azotemia BUN:Cr

A

> 20:1 to 30:1

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22
Q

postrenal azotemia or prerenal + renal azotemia BUN:Cr

A

high ratios with elevated Cr

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23
Q

Berthelot’s reaction

A

BUN method

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24
Q

sodium nitroprusside

A

BUN method

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25
Q

Nessler’s rxn

A

BUN method

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26
Q

glutamate dehydrogenase (GLDH) procedure

A

BUN method

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27
Q

Diacetyl or Fearon Reaction

A

BUN method

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28
Q

BUN RR

A

7-18 mg/dL

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29
Q

BUN is stable at room temp for —- hours, ——– refrigerated, and —– months frozen

A

24 hours
several days
2-3 months

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30
Q

B U N <8-10 mg/dL

A

overhydration

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31
Q

BUN 50-150 mg/dL

A

impaired GFR

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32
Q

BUN 150-250 mg/dL

A

severe renal impairment

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33
Q

convert from urea to urea nitrogen

A

BUN = 28 g/mol
urea = 60 g/mol

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34
Q

creatinine synthesized in liver from…

A

Arginine
Glycine
Methionine

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35
Q

creatinine

A

Waste product derived from creatine and creatine phosphate which is contained in the muscle

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36
Q

precursor to creatine

A

phosphocreatine

37
Q

production is proportional to the muscle mass of the individual and it is released into the body fluids at a constant rate

A

endogenous creatinine

38
Q

creatinine levels affected by 3 variables

A

Relative muscle mass
Creatine turnover
Renal function

39
Q

NOT affected by diet, which makes this such a desirable test to run for specimen validity

A

creatinine

40
Q

ID a fluid as urine

A

BUN
creatinine

41
Q

Jaffe reaction

Reaction between ———- and picric acid in an alkaline medium (————-) yielding a ————– compound

A

creatinine
alkaline picrate
red-orange

42
Q

decreases with age starting at 50

A

creatinine

43
Q

major product of purine (adenine and guanine) catabolism

44
Q

precursor to uric acid

45
Q

hyperuricemia definition

A

A serum uric acid concentration of…
>7.0 mg/dL in men
>6.0 mg/dL in women

46
Q

gout (primary hyperuricemia) patient population

A

men 30 to 50 years of age
7 times more common in men

47
Q

Occurs when monosodium urate precipitates in supersaturated body fluids

48
Q

precipitate acute attacks of gout

A

Alcohol
High-protein diets (organ meats)
Stress
Acute infection
Surgery
Certain medications

49
Q

gout tx

A

Diet adequate (not high) in protein
No alcohol
Normal weight maintenance
Drug therapy if needed

50
Q

Chemotherapy and radiation therapy in cancer patients (leukemia, lymphoma, multiple myeloma, polycythemia) can cause…

A

secondary hyperuricemia

Increased cell destruction of endogenous nucleic acids

51
Q

tx for secondary hyperuricemia

A

Allopurinol

52
Q

Enzyme deficiency of HGPRT (biosynthesis of purines)

A

Lesch-Nyhan Syndrome

53
Q

Lesch-Nyhan patient population

A

X-linked genetic disorder almost exclusively in males

54
Q

characteristics of Lesch-Nyhan

A

“Sandy diaper” uric acid crystals
Mental retardation
Abnormal muscle movements
Pathological aggressiveness
Self-mutilation

55
Q

causes of hypouricemia

A

Severe hepatocellular disease
Defective renal tubular reabsorption of uric acid
Fanconi’s syndrome
Wilson disease
Uricosuric drugs (Allopurinol)
Alzheimer’s
Parkinson’s

56
Q

Phosphotungstic acid

A

uric acid method

57
Q

allantoin

A

uric acid method

58
Q

uric acid sample handling

A
  • Uric acid is susceptible to bacterial action, so specimens should be refrigerated
  • Hemolysis and bilirubin ↓ uric acid
59
Q

renal clearance

A

The rate at which the kidneys remove a substance from the plasma or blood.

60
Q

why is creatinine a good indicator of GFR?

A
  • Freely filtered by the glomeruli
  • Not reabsorbed by the tubules
  • Released into the plasma at a constant rate
61
Q

formula for CrCl

A

clearance = UV/P

U = urine concentration in mg/dL
P = plasma concentration in mg/dL
V = urine flow in mL/minute (1440 min/24h)

62
Q

Creatinine clearance has to be corrected to an adult body surface area (BSA) of ——m2.

A

1.73

UV/P(1.73/BSA) = ClCr

Dubois formula

63
Q

Use to estimate glomerular filtration rate from the serum creatinine level in patients with chronic renal disease and those at risk for CKD

64
Q

In patients 18 years of age and older, the ——— equation is the best means currently available to use creatinine values as a measure of renal function.

A

Modification of Diet in Renal Disease (MDRD) Study Equation

65
Q

Normal protein:creatinine ratio

66
Q

Gold standard for measuring glomerular filtration rate

A

inulin clearance

67
Q
  • Water loading to stimulate diuresis
  • Bladder catheterization to assure completeness of collection
  • Careful timing of blood samples
A

inulin clearance

invasive

68
Q

Single-chained, non-glycosylated, low-molecular-weight protein synthesized by all nucleated cells

A

cystatin C

additional GFR measure

69
Q

Used primarily to test for renal tubular function in renal transplant patients when decreased tubular function indicates early rejection

70
Q

based on the “protein error of indicators.”

A

urinalysis protein mat

71
Q

microalbuminuria definition

A

30-300 mg albumin/g creatinine

72
Q

Most often associated with children and young adults following a group A streptococcal infection (e.g., strep throat)

A

Acute glomerulonephritis (AGN)

73
Q

glomeruonephritis secondary conditions

A

Edema—Especially periorbital (around eyes), knees, and ankles
HTN from mild to moderate
Electrolyte imbalance (Na+ and K+)

74
Q

Dysmorphic RBCs, RBC Casts

A

glomerulonephritis

75
Q

Associated with end stage of persistent glomerular damage with irreversible loss of renal tissue and chronic renal failure

A

Chronic Glomerulonephritis (CGN)

76
Q

May occur as a complication of glomerulonephritis or as a result of circulatory disorders that affect blood pressure and flow of blood to the kidney (DM, SLE)

A

nephrotic syndrome

77
Q

s/s nephrotic syndrome

A

Massive proteinuria (>3 g/day)
Pitting edema
Hyperlipidemia—Fat droplets, oval fat bodies
Hypoalbuminemia
Renal epithelial, waxy, and fatty casts

78
Q

Inflammatory process involving a bacterial infection of the renal tubules by gram-negative bacteria

A

pyelonephritis

79
Q

pyelonephritis-causing organisms

A

Escherichia coli
Klebsiella
Proteus
Enterobacter

80
Q

Most common cause is vesicoureteral reflux nephropathy.

A

chronic pyelonephritis

81
Q

CKD Stage GFRs
At increased risk
1
2
3
4
5

A

CKD Stage GFRs
At increased risk —>90
1 — >90
2 —60-89
3 — 30-59
4 — 15-29
5 — <15

82
Q

Acute increase in the serum creatinine level of 25% or more and GFR <10 mL/min.

A

renal failure

83
Q

majority of kidney stones

A

75% calcium oxalate with or without phosphate

84
Q

4 factors that influence formation of kidney stones

A
  • Increase in concentration of chemical salts as a result of dehydration or increase in salts in the diet
  • Change in urinary pH
  • Urinary stasis
  • Presence of a foreign body
85
Q

DM nephropathy protein/albuminuria

A

Proteinuria > 0.5g/day
or
Albuminuria ~300 mg/day

86
Q

dialysis

A

larger macromolecules are separated from low-molecular-weight compounds by their rate of diffusion through a semipermeable membrane

87
Q

formula for urea reduction ration (URR) in dialysis pts

A

URR = (predialysis BUN - postdialysis BUN)/predialysis BUN (100)

88
Q

most widely used method in assessing dialysis adequacy

A

urea kinetic modelling (UKM)

89
Q

dialysis pts are prone to…

A

coronary artery disease
left ventricular hypertrophy

Mercy CLS 5: Chemistry (24 decks)

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