1. The kidney,chronic kidney disease and WAGR kidney disease
Jeffrey Kopp, MD
CAPT, US Public Health Service
Kidney Disease Section

2. Kidneys on computerized tomography (CT) scan

3. Kidneys and what they do (1)

4. Product
Cars
Homeostasis
Waste
Smoke
Urine

5. Kidneys came early in animal evolution

6. 1 million nephrons in each kidney: each is glomerulus + tubule

7. Glomerular filtration: filtering small molecules from the circulation
Renal blood flow ~1000 mL/min
Renal plasma flow ~600 mL/min
Glomerular filtration rate (GFR) ~100 mL/min = ~150 L/day

8. One kidney, one million nephrons

9. Tubular reabsorption: reclaiming what we need before it heads down the tubule to the ureter, bladder, and out
Why does the kidney filter everything, and then reclaim what is needed and discard the rest?
THE GOOD
(unless excess)
Sodium
Potassium
Chloride
Bicarbonate
Calcium
Magnesium
Glucose
Amino acids
Vitamins B, C
etc
THE BAD
Urea
Uric acid
Creatinine
Toxins
etc
Keeping the baby, throwing out the bathwater

10. Creatinine physiology
Small molecule, released from muscle turnover
Production depends on muscle mass
Freely filtered through the the glomerulus
Serum levels depend upon muscle mass (higher when muscle mass is higher) and kidney function (higher when kidney function is poor)

11. When kidney function is impaired GFR declines linearly serum creatinine rises geometrically

12. Estimating kidney function from serum tests
Gold standard test
Infuse iothalamate, measure serum and urine levels, calculate kidney clearance of iothalamate
Requires IV and takes ~3 hr
Population
Name
Variables
P30%
40: 28, 52
Children
Schwartz 1976
Creatnine, height
Schwartz 2012
+ BUN, Cystatin C
Adults
MDRD
Age, sex, race, creatinine
75%
CKD-EPI (2012)
Same
87%
CKD-EPI-Cr/CystC (2012)
+ Cystatin C
92%

13. Chronic kidney disease stages
GFR
ml/min/1.73m2
Possible complications
Dose adjustment for meds excreted by kidney 1
Normal GFR; proteinuria or hematuria
>90 BP - 2
Mild CKD
60-90 3
Moderate CKD
30-60
BP, bone, CVD + 4
Severe CKD
15-30
BP, bone, CVD, anemia ++ 5
Kidney failure
= ESKD
<15
BP, bone, CVD, anemia, infection
+++

14. Assessing urine protein levels
Problem: in a particular patient at a particular phase of disease, protein concentration in urine fluctuates with urine concentration from sample to sample
Since the amount of urine creatinine/day is relatively constant, the concentration in urine provides an index of urine concentration or dilution
Solution: the protein/creatinine ratio or albumin/creatinine ratio will adjust for changes in urine concentration
Example of urines taken from the same patient at two different times of the day
Concentrated urine: albumin 10 mg/dL, creatinine 100 mg/dL = ACR 100 mg/g
Dilute urine: albumin 2 mg/dL, creatinine 20 mg/dl = ACR 100 mg/g

15. Assessing kidney function: urine tests
Blood
Protein
Urinalysis dipstick
Negative, Trace, 1, 2, 3
Negative, Trace, 1 ,2, 3
Urinalysis microscopic
Did the red blood cells come from the kidney? NA
Random urine
(children, adults)
Albumin/creatinine ratio (ACR)
mg/g: microalbuminuria (metabolic syndrome, early glomerulosclerosis)
>300 mg/g: macroalbuminuria - kidney disease
>1 g/g: nephrotic
Protein/creatinine ratio (PCR)
<0.2 g/g: normal
0.2-2 g/g: proteinuria
>2 g/g: nephrotic
24 hour urine collection
(adult values)
Albumin
mg/d: microalbuminuria >300 mg/d: macroalbuminuria – kidney disease
>150 mg/d: proteinuria
> 3.5 g/d: nephrotic

16. WAGR kidney disease

17. Wilms tumor: CKD is common when there is a genetic basis
National registry of Wilms tumor,
N = 5965 enrolled at <16 yr
Renal failure: cr>2.5 or dialysis
WAGR
Denys-Drash
Breslow Cancer Res 2000

18. NIH WAGR study Genotype/phenotype: relate phenotype to genes deleted
Random urine A/C in 24 subjects
ACR mg/g
<10
10-17
18+
<30 5 2 3
30-300 4
>300

19. Patterns of WAGR kidney diseases
Immature podocytes
Diffuse mesangial sclerosis
Focal segmental glomerulosclerosis

20. Screening for WAGR kidney disease
Screening: yearly BP check, serum creatinine and cystatin C, urine ACR (and possibly PCR)
Strive to maintain normal body weight: “bigness” stresses 2 kidneys, more so 1 kidney, and most 1 kidney with glomerulosclerosis
Maintain normal BP: if borderline, restrict dietary salt (2 g/d target) and check BP at home. BP target is 50th percentile BP for age and height.
If albuminuria appears, consider kidney biopsy to confirm that glomerulosclerosis is present (but probably no biopsy if single kidney)
No role for kidney ultrasound in diagnosing glomerular disease – will be normal until extensive fibrosis develops and substantial loss of function has occurred.

21. Treatment for WAGR kidney disease
Probably start therapy with renin-angiotensin pathway blockers – one drug and possibly two drugs
This approach slows glomerulosclerosis in other diseases but has not been tested in WAGR
These drugs lower BP and rise potassium, so these must be monitored.
Low sodium diet potentiates the anti-proteinuric effect of RAS blockers

22. Renin-angiotensin-aldosterone system (RAAS)
Angiotensinogen
Aliskiren
Trauma: maintains blood pressure, promotes wound healing
Chronic kidney disease: elevates blood pressure, promotes fibrosis – blocking RAAS is a key to slowing or halting kidney disease progression
ACE inhibitors
Angiotensin 1
Renin
Angiotensin 2
Angiotensin
converting
enzyme
Angiotensin receptor blockers (ARB)
Angiotensin receptor
Spironolactone
Eplerenone
Blood vessel constriction
Aldosterone
Aldosterone receptor
Sodium retention
Fibrosis

23. Renal replacement therapy

24. Hemodialysis Dialysis center or home 3x week or 6x week
Advantages: effective in large people, less for patient/family to do
Disadvantages: needles, vascular access problems, time spent in center, arranging treatments when traveling, disequilibrium after dialysis sessions

25. Peritoneal dialysis Continuous ambulatory: 4 1-2 liter exchanges/d
Intermittent: liters overnight, 1 exchange at night
PD Advantages: mobility, control, no needles
Disadvantages: more patient/family effort, less effective in large person, peritonitis

26. Kidney transplant: the preferred approach to renal replacement therapy

27. Kidney transplant: requirements to be donor
Age 18 – 55
Normal kidney function
No diabetes
No cancer, HIV, hepatitis B or C
Normal BP or possibly on 1 BP medication
Blood group match (can do plasmapheresis if not)
USRDS 2011

28. Induction antibody use Figure 7.28 (Volume 2)
Patients age 18 & older receiving a first-time, kidney-only transplant.
USRDS 2011

29. Immunosuppression use Figure 7.27 (Volume 2)
Patients age 18 & older receiving a first-time, kidney-only tx. CsA: cyclosporine A; CsM: cyclosporine microemulsion.
USRDS 2011

30. Acute rejection within the first year post-transplant Figure 7
Acute rejection within the first year post-transplant Figure 7.19 (Volume 2)
Patients age 18 & older.
USRDS 2011

31. Outcomes: living donor transplants Figure 7.18 (Volume 2)
Patients age 18 & older receiving a first-time, kidney-only transplant. Adj (survival): age/gender/race/primary diagnosis.
USRDS 2011

32. Renal transplant vs chronic dialysis
Longer survival
Better quality of life
There are concerns: immunosuppressive medications, infections (virus), cancer

33. The future Therapies for chronic kidney disease improve every year
Perhaps we can develop specific therapies for WAGR kidney disease