5/10/2012

1

Important Lab TestsImportant Lab Tests in

Diabetic Nephropathy

1 of 30

Dr. M Reza Bakhtiari, DLS, PhD

2 of 30

5/10/2012

2

3 of 30

4 of 30

5/10/2012

3

5 of 30

• UACR is a ratio between two measured substances. • Unlike a dipstick test for albumin, UACR is unaffected by variation in urine concentration.

Albuminuria

6 of 30

5/10/2012

4

7 of 30

8 of 30

• Proteinuria generally refers to a positive dipstick test for protein or to a daily output of protein above a certain cut point, typically 500 mg/d.

5/10/2012

5

9 of 30

10 of 30

5/10/2012

6

Serum Creatinine, Creatinine Clearance, and GFR(Interrelations)

11 of 30SIMON J et al. Cleveland Clinic Journal of Medicine 2011;78:189-195

12 of 30

5/10/2012

7

13 of 30

14 of 30

5/10/2012

8

15 of 30

16 of 30

5/10/2012

9

17 of 30

18 of 30

5/10/2012

10

Modification of Diet in Renal Disease (MDRD) Study equation

19 of 30

20 of 30

5/10/2012

11

Sources of Variability in Estimating GFR

• Biological variability in GFR (6.3% to 7.5% )

• Biological variability in serum Creat.(4.3%)

• Errors in the estimating equation• Errors in the measurement of serum creatinine

–Systematic Bias (<5.2%)

• calibration differences between measurement procedures

– Imprecision

21 of 30

Imprecision• within-laboratory effects (<3.3%)• laboratory random variability in day-to-day calibration • specimen-specific effects

–TE goal: (<11.5%)Clinical Chemistry January 2006 vol. 52 no. 1 5-18

22 of 30

5/10/2012

12

Creatinine Results of EQAP(Interlaboratory Imprecision)

23 of 30

Creatinine Results of EQAP(CV% vs Mean)

24 of 30

5/10/2012

13

Creatinine Results of EQAP(Modified CV% vs Mean)

25 of 30

Goal: <6.4%

Clinical Chemistry January 2006 vol. 52 no. 1 5-18

Creatinine Standardization Program

• Reference Method• Reference Method – Isotope Dilution–Mass Spectrometry (IDMS)

• IDMS Traceable Methods– NIST SRM 967

i l i f d d d h l

26 of 30

NIST= National Institute for Standards and Technology

SRM= Standard Reference Material (Creatinine in Frozen Human Serum)

5/10/2012

14

Thank you for your Attention

27 of 30