GFR
amount of plasma filtered thru the nephron per unit of time
How to measure?
**1.inulin (exogenous)- gold standard **
**2.creatinine (endogeneous) **
3.EDTA
4.DTPA
5.iohexol
6.iothalamate
7.Cystatin C
eGFR calculation evolution
- Cockcroft-Gault equation 1973
- MDRD 1999
- reexpressed MDRD 2005
- CKD epi 2009
Cockcroft-Gault equation
- overestimate in obese /edematous pt
*~ as the equation 140-age X **BW ** x 1.2 (male) / se creat
MDRD
- poorly validated in children / elderly / pregnant / ethnic group / those without CKD
- underestimate
characteristic of ideal clearance marker
- freely filtered
- not reabsorb / secreted
- not protein bounded
- no extra-renal elimination
- safe to administer & economical
Drawback of Creatinine
influences by
a. body mass
b. dietary intake (pt intake)
c. exercise
d. meds: bactrim / cimetidine
Conversion
mg/dL - umol/L : x 88.4
mg/dL - mmol/L : x 0.357
CKD-epi
- more accurate
- same variable as MDRD
- pooled of data fron CKD+ non CKD
Cystatin C
- non glycosylated pt (low molecular mass)
- produced by all nucleated cells
- filtered, reabsorbed, excreted (small amount)
- independent of age, muscle mass, sex, dietary
- expensive
- short half life, smaller volume distribution (useful in AKI)
- if eGFRcr 45-69 (3a) no marker for kidney damage — to proceed with cystatin C equation
- if eGFRcys <60 = CKD
- if eGFRcys >60 = CKD not confirmed - accurate in obese: as adipocytes no nucleus
definition of CKD
eGFR < 60ml/min/1.73m2 > 3/12 with or without kidney damage
**kidney damage > 3/12 **
(based on biopsy /imaging / urine) regardless eGFR
type of nuclear imaging
- GFR estimation: EDTA
- dynamic: DTPA, MAG 3
- static: DMSA
DTPA,MAG 3: renal blood flow,tubular secretion, urinary excretion, GFR
**DMSA **: anatomical abN, renal scarring (non-fx renal tissue)
what is pathological proteinuria?
type of proteinuria
1. glomerular: : failure of glomerular failure of high + intermediate MW pt (alb)
2. tubular: LMW pt (Ig light chain,b2 microglobulin) filtered but failure of reabsorb by prox tubules, neg on dipstick
3. overflow: overproduction of LMW pt exceed the capacity of reabsorption (sequalae of #2)
4. secretory: not albuminuric pt added to urine (UTI, bladder ca)
definition of
anuria
oliguric
polyuric
anuric: <100ml/ day
oliguric: < 400ml/day
polyuria: 3L/day
How SGLT2 works?
