1. Kidney diseases and failure 8.5.2010 nefro.ppt 1

2. Repetition of physiology  Regulation of water, electrolyte (blood pressure!) and acidobasic balance  Removal of metabolic endproducts, foreign substances and toxins (not everything – small molecules soluble in water)  Urea (carbamid), creatinine, uric acid  Endocrine function (renin and erytropoetin)  2*800 000 – 1 200 000 nephrons  Cortex and medulla Special blood supply : 1000 ml/min = 20% CO 8.5.2010 nefro.ppt 2

3. Filtration and clearance  Blood (plasma) flow and filtration is stable and independent on blood pressure (GFR = 2 ml/s, 120 ml/min, 180 l/d)  Filtration fraction: Ratio between filtration and plasma flow : 120/600 = 0,20 (20 %)  Clearance: Virtual amount of urine, which is cleared from a substance in a time unit  Clearance is dependent on  Filtration  Tubular secretion and resorbtion 8.5.2010 nefro.ppt 3

4. 8.5.2010 nefro.ppt 4

5. Proteinuria  Glomerular membrane = ultrafilter, the result is a solution similar to plasma but less protein  The pore diameter allows the passage of molecules < 30 kDa and the basal membrane has a negative charge  But it is10 g/d, in filtrate and only 25 mg in urine  Variable according to physical activity and postural position 8.5.2010 nefro.ppt 5

6. 8.5.2010 nefro.ppt 6 MEASUREMENT and ASSESMENT OF GFR Clearance of a substance which is only filtered = GFR Clearance = [U]/[P]*V [U][P] = cc in urine and plasma V = volume of urine Clearance = volume of plasma cleared

7. 8.5.2010 nefro.ppt 7 MEASUREMENT and ASSESMENT OF GFR Clearance = [U]/[P]*V [U][P] = cc in urine and plasma V = volume of urine Clearance = volume of plasma cleared Inulin (polysaccharide) Endogenous creatinine – not very exact Problems – 24h urine, method and secretion

8. 8.5.2010 nefro.ppt 8 ASSESMENT OF GFR Assesement from serum creatinine [Krea]*GFR = k GFR = k/[Krea] It is not so simple Creatinine syntheis is not stable: Age, muscle mass, meat in food… Not only filtered But cheap and simple

9. Theoretical association between serum creatinine and GFR 8.5.2010 nefro.ppt 9 1,5 1,3 1,1 0,9 0,7 0,5 0,3 GFR, ml/min

10. UriSed 8.5.2010 nefro.ppt 10

11. 8.5.2010 nefro.ppt 11

12. 8.5.2010 nefro.ppt 12 Classification of National Kidney Foundation USA, 2005 GradeGFR, ml/sPrevalence, USA, % SR 1> 1,5  or normal GFR 3,3165 000 21,0 – 1,49slightly  GFR 3,0150 000 30,5 – 0,99midlle  GFR 4,3210 500 40,25 – 0,49severe  GFR 0,210 000 5< 0,25Kidney failure 0,210 000