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Pathophysiology of Renal Disorders and Tests
1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA.
DEPT. OF PHYSIOLOGY
APPLIED RENAL
PHYSIOLOGY &
RENAL FUNCTION
TESTS
2. OBJECTIVES.
Pathophysiology of common renal disorders
Diuretics
Renal function tests
Dialysis and renal Transplantataion.
3. PATHOPHYSIOLOGY OF
COMMON RENAL DISORDERS
Common urinary symptoms
Renal failure
Nephrotic syndrome
Tuesday, May 1, 2018
4. COMMON URINARY
SYMPTOMS
Normal urine output
-800-2500ml/day
Polyuria > 3L/day
Common causes
Physiological –
Psychogenic, drug induced
Pathological – DI,
Mannitol infusion.
Nocturia- Excess urine
excretion at night.
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5. COMMON URINARY
SYMPTOMS
Dysuria -pain or burning during micturition.
Urgency of Micturirtion - Exagerrated sense or
urge to micturate
Enuresis – Involuntary passage of urine at night.
Oliguria- urine output< 500 ml/day.
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6. INCONTINENCE
Inability to retain
urine in bladder.
Causes
Neurogenic
Stress
Mechanical
Overflow
Psychogenic
Functional
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7. RENAL FAILURE
Deterioration of Renal function resulting in
decline in Glomerular filtration rate & rise in
urea & Non-nitrogenous substances in blood.
2 types
Acute
chronic
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8. RENAL FAILURE
ACUTE RENAL FAILURE
Sudden onset
Invariably reversible
Cause – Pre-renal or Post
renal
Uremia – recent onset.
Renal failure casts –
Absent
Sp Gravity – High
Dialysis – for short period.
CHRONIC RENAL FAILURE
Gradual
Usually irreversible.
Mostly renal
Uremia – more than 3
months
Renal failure casts –
Present
Sp Gravity – Low, fixed.
Dialysis – repeated,chronic
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17. ANALYSIS OF URINE
Glycosuria – presence
of Glucose in urine
DM
Renal Glycosuria
Alimentary Glycosuria.
Ketonuria – ketone
bodies in urine
Severe DM
Prolonged starvation
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18. ANALYSIS OF URINE
Bilirubinuria – > 1.35 mg
Bilirubin in urine with
increased conjugated
bilirubin in hepatic, post
hepatic jaundice.
Haemoglobinuria –
haemoglobin in urine
Intravascular haemolysis
in black water fever in
falciparum malaeria.
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19. ANALYSIS OF URINE
Microscopic
examinations
Casts
Crystals
Cells
Bacteriological
examination of urine
– for Pus cells &
Bacteria
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20. MICROSCOPIC EXAMINATIONS
Casts – Proteinaceous
plugs formed by
coagulation of Tamm-
Horsfall proteins
Cellular – coagulated
with protein material
Non-cellular – hyaline
& granular casts.
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21. MICROSCOPIC EXAMINATIONS
Crystals – Normally seen
are crystals of Ca oxalate,
CaPO4, Ca-NH4-Mg-PO4
Uric acid crystals &
cystine crystals -
significant
Cells – RBC, WBC,
tubular epithelial cells,
squamous epithelial cells.
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22. ANALYSIS OF BLOOD
Blood urea level – normal 20-40mg/dl
50% glomerular damage.
Plasma creatinine concentration.(0.6-1.5
mg/dl)
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23. ANALYSIS OF BLOOD
Serum protein levels
6.7-8 gm/dl
Albumin – 3-5 gm/dl
Globulin – 2-3 gm/dl
Serum cholesterol levels – 150-200 mg/dl.
Nephrotic syndrome
Serum electrolyte levels
Na – 152 mEq/L, K - 5 mEq/L, Ca 9-11 mg/dl.
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24. MEASUREMENT OF GFR
If a substance (W) is neither reabsorbed nor secreted
by tubule:
The amount excreted in urine/min. will be equal
to the amount filtered out of the glomeruli /min.
Amount of substance excreted in urine/min
= UW V ……………….. 1
UW–Urine conc of w
V – Urine volume per unit time
25. MEASUREMENT OF GFR
Rate at which a substance is filtered by the glomeruli
can be calculated:
Quantity filtered = GFR x PW …………… 2
P = Concentration in plasma.
Amount filtered = amount excreted
GFR x PW= UW V from eq 1 & 2
GFR = UW V
------------
PW
26. CRITERION FOR W
Freely filterable at renal corpuscle
Not reabsorbed
Not secreted.
Not synthesized by renal tubules.
Not metabolized by renal tubules.
only one substance --- INULIN
27. CLEARANCE
Definition :-
Amount of plasma completely cleared of the
substance by kidney in unit time by excretion of that
substance in urine.
Basic clearance formula
Cw = mass of w excreted / time
---------------------------
Pw
= Uw V
----------------------
Pw
28. INULIN CLEARANCE
Inulin –
dye, fructopolysaccharide,
does not exist naturally,
measure of GFR – not reabsorbed, nor secreted, nor-
metabolized, non-toxic,
Method – single bolus dose
i/v infusion,
urine/ plasma conc,
urine flow rate,
Cin = Uin V / Pin
29. CLINICAL APPLICATION
An indicator of plasma clearance mechanism.
Cw = Cin clearance ratio 1
e.g. mannitol, sorbitol, vit B12, sucrose
Cw < Cin clearance ratio < 1
e.g. Glucose, xylose, fructose
Cw > Cin clearance ratio > 1
e.g. Para-amino hippuric acid (PAH),
phenol red
30. CREATININE CLEARANCE
Adv.– More preferred
No intravenous dose needed.
Endogenous substance from metabolism of muscle
creatine
Filtered & marginally secreted
Method:-
24 hr urine collection, urine conc,
mid-point plasma conc sample,
Normal Value – 130 ml/min
31. UREA CLEARANCE
Urea- End product of protein metabolism.
Filtered & partly reabsorbed
Clearance less than GFR
Influenced by protein content of diet.
METHOD :-
Empty bladder,
urine collected at the end of 1 hour,
blood sample collected at mid point
estimate blood & urine urea.
32. UREA CLEARANCE
Urea clearance drastically changes – urine output <
2ml /min
So 2 urea clearance values
1 Maximal :- urine output > 2 ml.
CU = UV/ P
Normal value = 75 ml / min
2 Standard :- urine output < 2 ml.
CU = U √ V/ P
Normal value = 54 ml / min
33. MEASUREENT OF RENAL PLASMA
FLOW
FICK’S Principle to kidney
“ Amount of substance excreted by
the kidney per unit time (UV) is equal
to the product of renal plasma flow
(RPF) and arteriovenous difference in
its plasma concentration.”
UV = RPF (Pa- Pv)
RPF = UV / (Pa-Pv)……………(1)
34. PAH CLEARANCE – TO
MEASURE RPF
PAH clearance is used to measure
RPF
b’coz–
1 Completely extracted.
2 Neither metabolized nor
reabsorbed.
3 Does not affect RBF.
4 Actively secreted.
5 Conc. easily measured.
35. METHOD
RPF = UV/ (Pa – Pv)
All PAH excreted in urine nothing returned
so Pv is 0
RPF = UV / Pa
Also PAH not excreted by any other organ so plasma PAH
conc can be used.
RPF = UV / P PAH
BUT UV / P PAH= PAH Clearance
So RPF = PAH Clearance.
ERPF = PAH Clearance.
TRUE ERPF = CPAH / 0.9
36. RENAL CLEARANCE TESTS TO ASSESS
OSMOTIC AND FREE WATER CLEARANCE
Osmotic clearance –
Amount of plasma
completely cleared of
osmotically active
solutes that appear in
the urine each min.
Free water clearance –
The quantitative
measure of kidneys
ability to excrete water.
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37. TESTS FOR TUBULAR
FUNCTIONS
Urine concentration tests
Urine dilution tests
Urine acidification tests
Other methods of study of tubular functions.
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38. URINE CONCENTRATION
TESTS
Measuring specific gravity of urine after 12 hrs of
water deprivation or after giving vasopressin
If above 1.020 normal
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39. URINE DILUTION TESTS
Pt asked to drink 1 l of water & measure urine
sample for 4 hours, - 750 ml should be collected &
one sample osmolality should be less than
100msom/Kg of water.
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40. URINE ACIDIFICATION TESTS
Pt given NH4Cl (0.1 gm/kg) & urine sample
collected after 6 hrs
Urine pH should be below 5.3
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41. OTHER METHODS OF STUDY
OF TUBULAR FUNCTIONS.
Micro Puncture technique
Micro Cryoscopic studies
Micro Electrode studies.
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43. RENAL BIOPSY
Per cutaneously with
the help of Vim-
silvermann needle.
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44. DIALYSIS AND RENAL
TRANSPLANTATAION.
Dialysis – diffusion of
solute from an area of
higher conc to lower
conc through
semipermeable
membrane
Uremia – when 75%
of nephrons are
damaged.
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45. HAEMODIALYSIS OR
ARTIFICIAL KIDNEY
In acute renal failure,
circulatory shock or
mecury poisoning.
Radial artery is
connected to
haemodialysis machine &
blood is passed through
long & coiled cellophane
tube immersed in dialysis
fluid.
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