CVPR Week 8: CKD Flashcards
Objectives
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How to measure kidney function and assess kidney damage
EGFR and Albuminuria
What do EGFR and Albuminuria tell you?
Kidney function and assessment of kidney damage
EGFR AKA
Estimated glomerular filtration rate
Test of renal damage
protein in the urine (albuminuria)
Test of renal function
EGFR
How to calculate EGFR
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GFR vs eGFR
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When not to use creatinine-based estimates of kidney function
- in AKI when creatinine levels can be rapidly changing
- extremes of muscle mass, body size or altered diet patterns
- medications that interfere with the measurement of serum creatinine
Examples of medications that interfere with the measurement of serum creatinine
- Trimethoprim
- vitamin D analogs
- Tenofovir
Different eGFR estimating equations
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/630/492/a_image_thumb.png?1557093483)
What is Cystatin-C?
a novel measure of renal function
Cystatin-C vs Creatinine
estimating equations have been developed to use Cys-C alone or with SCr but creatinine and Cys-C don’t always agree
Describe the physiologic basis of proteinuria/albuminuria
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How is CKD screened for?
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Normal to mildly increased albuminuria: 24-hour excretion
<30 mg/day
Normal to mildly increased albuminuria: timed urine specimen
<20 ug/min
Normal to mildly increased albuminuria: spot urine albumin/creatinine ratio (ADA)
< 30 mg/g
Normal to mildly increased albuminuria: Spot urine albumin/creatinine ratio (gender specific) (K/DOQI)
<17 mg/g (men)
<25 mg/g (women)
Moderately increased albuminuria: Spot urine albumin/creatinine ratio (gender specific) (K/DOQI)
17-250 (men)
25-355 (women)
Moderately increased albuminuria: Spot urine albumin/creatinine ratio (ADA)
20-300 mg/g
Moderately increased albuminuria: Spot urine albumin-specific dipstick (screening)
>3 mg/dL
Moderately increased albuminuria: Timed urine specimen
20-200 ug/min
Moderately increased albuminuria: 24-hour excretion
30-300 mg/day
Severely increased albuminuria: Spot urine albumin-specific dipstick (screening)
N/A
Severely increased albuminuria: Spot urine albumin/creatinine ratio (ADA)
>300 mg/g
Severely increased albuminuria: Timed urine specimen
>200 ug/min
Severely increased “macro-albuminuria” spot urine albumin/creatinine ratio (gender specific) (K/DOQI)
>250 (men)
>355 (women)
Dipstick urine tests
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Urine protein/creatinine ratio test uses
All proteins, not albumin (myeloma/CIN)
UACR AKA
Urine albumin-to-creatinine ratio
Urine albumin-to-creatinine ratio (UACR) test uses
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Which urine test is best?
ACR > PCR > Auto strip > Manual strip
How is urinary ACR not perfect
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Urinary ACR and transient elevation in albuminuria
- menstrual blood contamination
- symptomatic UTI
- Exercise
- upright posture (orthostatic proteinuria)
- Other conditions increasing vascular permeability
Urinary ACR and intraindividual variability in creatinine excretion
- intrinsic biological variability
- genetic variability
Urinary ACR and preanalytical storage conditions
degradation of albumin before analysis
Urinary ACR and non-renal causes of variability in creatinine excretion
- Age (lower in children and older people)
- Race (lower in caucasian than black people)
- Muscle mass (lower in people with amputations, paraplegia and muscular dystrophy)
- gender (lower in women)
Changes in creatinine excretion
Non-steady state for creatinine (AKI)
Urinary ACR and antigen excess
Samples with very high albumin concentrations may be falsely reported as low or normal using some assays
Prozone effect
Samples with very high albumin concentrations may be falsely reported as low or normal using some assays
What is the definition of CKD?
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