Nagarajan's Basics
in Nephrology
What are the anatomical compartments in
the kidney ?
Vascular
Glomerular
Tubular
Interstitium
Collecting system – intra renal
and extra renal
What are the physiological process
involved in Urine formation?
Glomerular
filtration
Tubular reabsorbtion
Tubular secretion
What are the functions of Kidney and
effect s of its nonfunctioning ?
Excretory
function Uremia
Fluid balance Fluid overload
Electrolyte balance Hyperkalemia
Blood pressure Hypertension
Acid base balance Metabolic acidosis
Endocrine function Anemia, Bone disease
How to use the terminologies Acute or
Chronic and Kidney Failure or Kidney Disease ?
Any Kidney disease with evidence of disease process more
than three month is denoted as “Chronic kidney Disease”
The Term Kidney Failure no longer used for denoting all
kidney damages. It is restricted to
the dialysis requiring patients only.
The term Acute renal Failure and Chronic
Renal Failure should be used only in dialysis requiring patients.
The term Chronic kidney disease or Acute Kidney Injury is used with appropriate stage for the diagnosis
of all patients with kidney disease.
For Example
Chronic
Glomerulo Nephritis / Chronic Kidney
disease Stage 4
Chronic Interstitial Nephritis /
Chronic Kidney disease stage 2
Acute Kidney Injury / Acute Tubular Necrosis
What are the importance of staging
Chronic kidney disease?
Facilitate defining Epidemiology of CKD
Provide common language for patients
& practitioners
Framework for evaluation &
management of CKD
What are the stages of Chronic Kidney
Disease ?
Chronic kidney disease staging done based on the evidence of
Kidney Damage and Estimated Glomerular
Filtration Rate( e GFR)
Stage
|
Description
|
eGFR
(ml/mt/1.73 m2)
|
Remarks
|
1
|
Kidney damage with normal or elevated
GFR
|
> 90
|
Evidences for kidney damage is must for diagnosis
|
2
|
Kidney damage with mildly decreased
GFR
|
60 to 89
|
Evidences for kidney damage is must for diagnosis
|
3 A
|
Moderately decreased GFR
|
45 to 59
|
No evidences of Kidney damage needed
|
3 B
|
Moderate to severely decreased GFR
|
30 to 44
|
No evidences of Kidney damage needed
|
4
|
Severely decreased GFR
|
15 to 29
|
No evidences of Kidney damage needed
|
5
|
Kidney failure
|
Less than 15
|
Dialysis requiring stage
|
What are the evidences required to
diagnose Kidney damage or Kidney Disease?
Kidney damage defined by
structural or functional abnormalities of the Kidney with or without decreased
GFR, manifest either by
Markers of kidney
damage -
abnormalities of composition of
blood -
Increased Blood Urea and Serum
Creatinine Levels
urine abnormalities –
Proteinuria, Hematuia, Casts etc
Abnormalities in Imaging tests(X Ray, USG Abdomen, CT ,MRI
etc)
Pathological abnormalities - Abnormalities in Kidney Biopsy
What are the stages of Acute Kidney
injury ?
Stage
|
Serum Creatinine
|
Urine Output
|
1
|
1.5–1.9
times increase from baseline
OR
>
0.3 mg/dl increase
|
<
0.5 ml/kg/h for 6–12 hours
|
2
|
2.0–2.9 times baseline
|
0.5
ml/kg/h for
>
12 hours
|
3
|
>3.0
times increase from baseline
OR
Increase
in serum creatinine to > 4.0 mg/
OR
Initiation
of renal replacement therapy
OR
In patients
<
18 years, decrease in eGFR to <35 ml/min per 1.73 per square metre body
surface
|
<
0.3 ml/kg/h for > 24 hours
OR
Anuria
for > 12 hours(Obstruction ruled
out)
|
How
to Assess Renal Function ?
Glomerular filtration rate
Represents excretory
function of the Kidney
1. Endogenous
creatinine clearence
GFR is often
estimated using serum creatinine concentrations [Cr]. Creatinine (Cr) is a
metabolite of creatine (intermediate in muscle energy metabolism). Cr is freely filtered at the glomerulus with
no tubular reabsorption and minimal secretion (10%). The rate of production determined by muscle mass.
Normaly Cr excreted = Cr filtered (at steady state).
Rrequires blood and 24 hour urine samples; measure plasma [Cr], 24 hour
urine volume
and urine
Creatinine[Cr]
GFR = urine [Cr] x urine
volume/plasma [Cr] x duration of urine collection in minutes
(Increasing Cr
secretion can overestimate true GFR, particularly in azotemic patients
Incomplete urine collection can underestimate
true GFR; over-collection of urine overt'stimates it )
2. Estimated Glomerular Filtration(
e GFR)
eGFR is reported in
millilitres per minute which is written as
mL/min/1.73m2.
(the “1.73m 2” indicates a result expressed relative to body
surface area).
Estimated
Creatinine Clearence (Cockcroft - Gault Formula)
CrCl (mg/dl) ~ (140 - age)(body mass) /
(plasma [Cr] x 72)
(multiply above result by 0.85 for women, normal range is >90 ml/min)
MDRD
equation : (Online Calculator)
186 x (Creat / 88.4)-1.154
x (Age)-0.203 x (0.742 if female) x (1.210 if black)
CKD
EPI Formula (Online Calculator)
CKD-EPI equation expressed as a single equation:
GFR
= 141 × min (Scr /κ, 1)α × max(Scr /κ, 1)-1.209
× 0.993Age × 1.018 [if female] × 1.159 [if black]
where:
Scr is serum creatinine in mg/dL,
κ is 0.7 for females and 0.9 for males,
α is -0.329 for females and -0.411 for males,
min indicates the minimum of Scr /κ or 1, and
max indicates the maximum of Scr /κ or 1.
where:
Scr is serum creatinine in mg/dL,
κ is 0.7 for females and 0.9 for males,
α is -0.329 for females and -0.411 for males,
min indicates the minimum of Scr /κ or 1, and
max indicates the maximum of Scr /κ or 1.
When Not to Use Creatinine-based Estimating Equations ?
Individuals with unstable
creatinine concentrations
Creatinine-based estimates of
kidney function are only useful when renal function is stable; serum creatinine
values obtained while kidney function is changing will not provide accurate
estimates of kidney function.
Persons with extremes in muscle
mass and diet.
This includes, but is not
limited to, individuals who are amputees, paraplegics, bodybuilders, or obese;
patients who have a muscle-wasting disease or a neuromuscular disorder; and
those suffering from malnutrition
What are the
essential elements to be defined in a patient detected to have kidney disease
in the management aspect?
Acute or Chronic
Primary or secondary
Renal function impaired or not
Which compartment involved in the disease process
Renal Replacement therapy (Dialysis
or Transplantation ) required or not
What is the probable pathology of
the disease
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