L81 - Biochemical Investigation of Urogenital Diseases II Flashcards Preview

MBBS I CPRS > L81 - Biochemical Investigation of Urogenital Diseases II > Flashcards

Flashcards in L81 - Biochemical Investigation of Urogenital Diseases II Deck (70)
Loading flashcards...
1
Q

Major urinary proteins?

IAABRC

A
  • IgG
  • Albumin
  • a1-Microglobulin

-Retinol Binding
Protein (RBP)

  • Cystatin C
  • B2-Microglobulin
2
Q

Filtration of protein in down to which metrics?

A

molecular size (20 - 40A)

protein molecular mass ( 30 - 70kDa)

Charge

3
Q

How does charge influence protein filtration?

A

Negatively charged molecules have lower permeability

4
Q

Proportion of Albumin relationship with severity of proteinuria?

A

proportion of Albumin increases with increasing severity of proteinuria

5
Q

Normal daily excretion of protein? What protein makes up 40-50% excretion?

A

< 150 mg;

about 40 - 50% is Albumin

6
Q

3 types of proteinuria?

A

Glomerular

Tubular

Overflow

7
Q

What causes glomerular proteinuria?

A

Increased glomerular permeability

8
Q

What causes overflow proteinuria?

A

Increased plasma concentration of

relatively freely filtered proteins

9
Q

What is the consequence of glomerular proteinuria?

A

Progressively increasing excretion
of higher molecular weight proteins

because permeability increases

10
Q

Give 5 CAUSES of tubular proteinuria?

A

1) PCT damage
2) DCT damage
3) Decreased nephron number

4) Orthostatic proteinuria
5) Transient proteinuria

11
Q

What is the consequence of PCT damage in Tubular proteinuria?

A

decreased tubular reabsorptive capacity and/or release of intracellular components

12
Q

What is the consequence of damaged nephron number in Tubular proteinuria?

A

Decreased nephron number:

increased filtered load per nephron

13
Q

Give examples of proteins excreted due to overflow proteinuria?

A
  • Bence Jones protein (BJP)
  • Lysozyme
  • Myoglobin (not haematuria but due to breakdown)
14
Q

What is orthostatic proteinuria?

A

Protein excretion varies with posture,

increasing on standing/
prolonged upright posture

15
Q

What is transient proteinuria?

A

Mild to moderate proteinuria

due to systemic illnesses apparently not related to the kidneys

16
Q

Give examples of causes of transient proteinuria?

A
  • high fever,
  • congestive heart failure,
  • seizures
  • strenuous exercise
  • urinary tract infection
17
Q

What is the normal urinary albumin: creatinine ratio in male and female?

A

≤2.5 (males)

≤3.5 (females)

18
Q

Normal Urine Reagent

Strip (‘dipstick’) reading?

A

Negative

19
Q

Normal Urine Protein:

Creatinine ratio mg/mmol?

A

<15 mg/mmol

20
Q

Normal Urine Total

Protein Excretion g/24h?

A

<0.15 g/24h

21
Q

Urinary protein measurements should be taken in What new discovered changes in blood metrics?

A

raised serum creatinine / reduced GFR

haematuria (esp. microscopic haematuria)

22
Q

What is urinary protein measurement for?

A

Assessment of severity of known kidney disease

e.g.Structural renal tract disease, recurrent renal calculi

23
Q

Urinary protein measurement should be included when initially assessing which patients?

A

patients with hypertension

patients with newly diagnosed type 2 diabetes

Family history/ hereditary stage 5 CKD

Suspected multisystem disease, e.g., SLE

24
Q

2 methods to collect urine protein specimen? (think timing)

A

Timed: 24-hour, 12-hour overnight, 4-hour

Random: assess Urine Protein / Creatinine ratio

25
Q

Dipstick method for urrine protein is sensitive to what protein? The dipstick is poort for detecting what?

A
  • Most sensitive to albumin

* Poor method for detecting tubular proteinuria

26
Q

Name of reagent in dipstick and colour change in detecting protein?

A

Tetrabromphenol blue

green in the presence
of protein

yellow in its absence

27
Q

Why is Dipstick a Poor method for detecting tubular proteinuria?

A

less sensitive to globulins, Bence Jones protein, mucoproteins, and hemoglobin

28
Q

How does Sulfosalicylic acid change with increasing protein concentration?

A

Increasing turbidity/ opaqueness

More and more precipitated until Flocculent precipitate

29
Q

Name some drug that can cause false positive proteinuria in urine dipstick or Sulfosalicylic acid?

A

Sulfonamide

High levels of penicillin or cephalosporin

Radiocontrast media

Urine pH > 8

30
Q

How to collect 24h urine sample?

A

First void of the day should be discarded

all urine passed in the next 24 hours collected

31
Q

2 main Disadvantages of timed urine collection?

A

inconvenient for patients

significant inaccuracies: incomplete collection, timing errors, intra-individual
variation

32
Q

Spot urine specimen usually done when?

A

Can choose random spot specimen or first morning spot specimen

UACR test most accurate with morning spot test

33
Q

Which method is used: timed 24 hours or Spot urine Pr/Cr ratio ?

A

Spot urine Pr/Cr ratio

34
Q

In individuals with large muscle mass, how does the UPCR or UACR test result chnage?

A

creatinine excretion may be much higher than
average population

> > UPCR (or UACR) will
underestimate proteinuria

35
Q

Cachectic patient or a patient with small muscle mass, how does the UPCR or UACR test result chnage?

A

creatinine excretion may be much lower than average population

> > UPCR (or UACR)
will overestimate proteinuria

36
Q

What is UPCR and UACR?

A

Urine protein: creatinine ratio

Urine albumin: creatinine ratio

37
Q

Factors affecting urinary albumin: creatinine ratio?

A

Transient elevation in
albuminuria (e.g. exercise, posture, UTI)

Intraindividual variability

Non-renal causes of
variability (e.g. age, race, gender)

38
Q

What is urine albumin a marker for?

A

marker of the risk of development of renal damage in diabetic patients

39
Q

Elevated urine albumin is an established marker of What?

A

cardiovascular risk in the diabetic and nondiabetic

populations

40
Q

What does microalbuminuria indicate?

A

increase in urinary excretion of
albumin

above the reference interval for healthy
nondiabetic subjects

41
Q

What is the 24h urinary albumin for microalbuminuria and macroalbuminuria?

A

Micro = 30-300mg/day

Macro = >300mg/day

42
Q

How does albumin exretion rate change with time for a type I DM patient?

A

Steadily increases until it overtakes GFR which steadily drops&raquo_space; renal failure

43
Q

What is the initial compensation mechanism of increased albumin loss?

A

Hyperfiltration

44
Q

Serum creatinine starts rising at which stage of CKD?

A

After stage 2

When eGFR is lower than 60

45
Q

Microalbuminuria starts at which stage of CKD?

A

Stage 1

> 90 eGFR

46
Q

Why should albuminuria be confirmed on at least 2 occasions?

A

high biological variability and nonrenal influences

47
Q

Measurement of what allows the use of spot sample?

A

Urine albumin-to-creatinine ratio

48
Q

What is the triad of nephrotic syndromes in relation to serum protein?

A

triad of heavy proteinuria, hypoalbuminemia,

and edema

49
Q

Criteria of proteinuria for nephrotic syndrome?

A

Proteinuria > 3.5 gm/day/1.73 m2

50
Q

Explain what occurs in rhabdomyolysis?

A

Large amounts of myoglobin are released into the plasma,

saturating the tubular reabsorptive mechanism

51
Q

What happens to myoglobin in kidney normally?

A

catabolized by endocytosis and proteolysis

in PCT

52
Q

What can myoglobinuria cuase?

A

directly toxic to the renal tubules

acute tubular necrosis with acute kidney injury

53
Q

What are the 2 diagnostic tests for myoglobinuria?

A

plasma creatine kinase, urine myoglobin

(Positive reaction with hemoglobin reagent
strip tests)

54
Q

What are some physical and chemical promoters of renal stone formation?

A

Chemical = calcium, urate, sodium

Physical = urinary tract obstruction, stasis

55
Q

What 3 factors cause supersaturated solution of salt which can form renal stone?

A

Urinary volume decrease

Excess excretion of stone components

pH increase

56
Q

What are some predisposing factors for renal stones?

A

Metabolic disorders

Hot climate

Protein rich diet

57
Q

Why know the type of renal tone helps?

A

helps delineate
the best treatment option + identification of risk factors = prevent
recurrence

e.g. Targeted therapeutic intervention or medical prophylaxis for recurrence

58
Q

Does renal stone analysis reflect the functional status of the
kidneys?

A

no

59
Q

Name some high risk conditions for recurrent renal stone formation?

A

Residual stone fragments

Uric acid and urate stones

Hyperparathyroidism

Nephrocalcinosis (increase Ca)

Family history of stones/ genetic determined stones

60
Q

Name some genetic determined stones?

A
  • Xanthine
  • Cystic fibrosis
  • Cystinuria
61
Q

What are the 3 analysis needed for treating renal stones?

A

Renal stone analysis

Blood and urine analysis

62
Q

What are the 5 common types of stones?

CPC MAP CUACO

A

Calcium Phosphate/Carbonate

Magnesium, Ammonium and Phosphate (Struvite
stones)

Calcium Oxalate

Uric acid

Cystine

63
Q

What causes Calcium Phosphate/Carbonate stones?

A

primary hyperparathyroidism or renal tubular acidosis

64
Q

What causes Magnesium, Ammonium and Phosphate (Struvite

stones) stones?

A

urinary tract infections&raquo_space; urease-producing organisms

> > (e.g. staghorn
calculus)

65
Q

What causes Calcium Oxalate stones?

A

aetiology often obscure

e.g. idiopathic hypercalciuria, excess calcium ingestion, hyperparathyroidism

66
Q

Which renal stone is the most common?

A

Calcium oxalate

67
Q

What causes Uric acid stones?

A

consequence of hyperuricaemia

68
Q

What causes Cystine stones?

A

very rare, associated with cystinuria

69
Q

What biochemical markers are checked in lab investigation of renal stones?

A

24h Urine sample:
check volume, and all the ions in diff. types of stones

Early morning urine: pH, amino acids, microscopy and culture

Blood:
check ions in stones

70
Q

What techniques are replacing biochemical investigation of renal stones?

A

infrared spectroscopic study and diffraction

crystallography

Decks in MBBS I CPRS Class (78):