2. 1.
2.
3.
Introduction of the Kidney structure
function
Identify the biochemical kidney
function test routine KFTs.
Do and Interpret the kidney function
tests properly.
Objectives
3.
For early detection because patients with kidney
disease have few signs and symptoms early in
disease course especially to high risk people.
Confirm the diagnosis of renal disease.
Give an idea about the severity of the disease .
Follow up renal disease progression and the
treatment.
Kidney Function Tests Used To
4. Sings Conditions for do KFT
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A change in how much you urinate
Pee that is foamy ,bloody ,discolored ,or
brown
Pain while you pee
Swelling in your arms ,hands ,legs ,ankles ,
around your eyes ,face ,or abdomen
Restless legs during sleep
Mid-back pain around the kidneys
You’re tired all the time
High blood pressure
Heart disease
Diabetes
5.
Urine Formation (3 Processes ):
Glomerular Filtration:
Ultrafiltration of plasma in the glomerulus producing cells-
and protein -free filtrate which passes to the Bowman’s
capsule.
Tubular Reabsorption:
Reabsorption of important molecules back to the blood
(water, a.a. glucose and ions).
Tubular Secretion:
Secretion of waste and toxic substances into the tubules.
Urine Excretion
Non-nitrogenous substances
*Bilirubin *Metabolites *Drugs/Toxins
Non-protein nitrogenous NPN substances
*Urea *Creatinine *Uric Acid
Production of Hormone: EPO Renin
Functions of the Kidney
6. Signs and Symptoms of Kidney
Disorders
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Early Symptoms
Weight loss
Nausea, vomiting
Fatigue
Headache
Frequent hiccups
Generalized itching
(pruritus)
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Late Symptoms
Increased or decreased
urine output
Need to urinate at night
Easy bruising or bleeding
Decreased alertness
Muscle cramps
Decreased sensation in
the hands and/or feet.
Edema
7. Types of Renal Disorders
I.
II.
Acute Renal Failure (ARF)
Occurs quickly and suddenly as a result
of kidney injures
Chronic Renal Failure (CRF)
Occurs gradually and slowly as a result of
a long-term disease
8.
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Pre-renal causes:
Reduced perfusion due to:
Blood loss (hemorrhage)
Cardiac failure
Peripheral vasodilation resulting in hypotension
(e.g. anesthesia)
Renal artery Obstruction:
Stenosis, embolism, or thrombosis
Types of Renal Disorders
9.
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Renal Cause:
Acute Glomerulonephritis due to:
Infections (e.g. post-streptococcal infection)
Autoimmune disorders (e.g.systemic lupus
erythematosus SLE)
Acute Tubular Necrosis due to:
Renal Ischemia (↓O2).
Hemolysis (Hb degradations interfere tubules
Toxins or Medications (e.g. carbon tetrachloride
CCl4, insecticides, etc.)
Types of Renal Disorders
10.
1)
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Post-renal causes:
Obstruction of renal flow due to:
Renal Calculi.
Benign or malignant masses
Normal kidney function can be restored if the basic
cause is corrected.
Chronic obstruction of the urinary tract, lasting for
several days or weeks, can lead to irreversible
kidney damage.
Types of Renal Disorders
11. Classification of kidney function
test
1)
1)
2)
Glomerular Function
Serum Urea, Creatinine and Uric acid
Clearance Tests
Proteinuria
Hematuria
Tubular Function
Specific Gravity
Urine Analysis
Physical, Chemical and Microscopic
Examination of urine
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Creatinine is the waste product formed in muscle by creatine
catabolism .
98% of the body creatine is synthesised in the liver pases into
circulation and is taken by skeletal muscle where it functions as
store of high energy in the form of creatine phosphate.
2 % of total muscle creatine produced is converted daily to
creatinine through the spontaneous, non enzymatic loss of
water or phosphate.
Creatinine in the plasma is filtered freely at the glomerulus and
secreted by renal tubules (10 % of urinary creatinine).
1) Serum creatinine
15.
16.
Jaffee Method (the Classic
technique)
Principle :
Creatinine reacts with picric acid at alkaline medium
to form red color complex we follow the
developing of the red color photometrically at
510 nm .
Method Principle of s.creatinine
determination
Creatinine + Picric Acid Colored
chromogen
Alkaline
17. Samples and Reagents
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Serum /Plasma or Urine (Random or24h)
Urine must be diluted 1:100 with D.W
Reagents:
CREA R1 (Picric acid)*
CREA R2(sodium tetraborate)
STD = 2 mg/dl
Note:
Hemolysis ,bilirubinemia and lipidemia will
interfere with test and lead to false decrease in
creatinine .
W.R1 part of R1 : part of R2
18. Procedures
1.Pipette into clean dry test tubes labeled as B ,S
T:
T )ml) S )ml) B )ml) Addition sequence
1 1 1 Working Reagent (L1+l2)
2. Incubate for 5 mins at 37 C°
3. Add the following :
- - 0.1 Distal water
- 0.1 - Standard
0.1 - - Sample
Mix well and incubate for 60 seconds at 37 C° and record
A1
After exactly 60 seconds record again A2 for S T against
blank at 510 nm.
19. Calculation Normal Range
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Creatinine conc. in mg/dl = × 2
Serum Creatinine:
Male = 0.7 – 1.2 mg/dl
Female = 0.6 – 1.1 mg/dl
Urine 24h = 800-1800 mg/24h
A2-A1(Sample )
A2-A1(Standard )
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Clearance is the volume of plasma cleared from the substance
excreted in urine per minute.
It could be calculated from the following equation:
Clearance (ml/min) = U V
P
U = Concentration of creatinine in urine mol/l
V = Volume of urine per min(24h)*
P = Concentration of creatinine in serum mol/l
CLEARANCE
CLEARANCE
21. 1)
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Accurate measurement of GRF by
clearance tests requires determination of
the concentration in plasma and urine of a
substance that is:
Freely filtered at glomeruli.
Neither reabsorbed nor secreted by tubules.
Its concentration in plasma needs to remains constant
throughout the period of urine collection.
Better if the substance is present endogenously.
Easily measured.
Eg: Inulin ,urea , radiolabeled EDTA and Creatinine clearance
*Creatinine meets most of these criteria.
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In young adults. :Creatinine clearance is usually about
90 – 140 ml/min (Males)
80 – 125 ml/min (Females)
It falls slowly but progressively to about 70 ml/min in individuals over 8o
years of age.
In children, the GFR should be related to surface area, when this is done,
results are similar to those found in young adults.
Creatinine clearance test is a more sensitive
indicator of kidney
function than serum creatinine and BUN alone
Plasma creatinine is an endogenous substance not affected by diet.
Plasma creatinine remains fairly constant throughout adult life
CREATININE CLEARANCE
CREATININE CLEARANCE
23. Cockcroft-Gault Formula
for Estimation of GFR
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As indicated above, the creatinine clearance is measured by
using a 24-hour urine collection, but this does introduce the
potential for errors in terms of completion of the collection.
An alternative and convenient method is to employ various
formulae devised to calculate creatinine clearance using
parameters such as serum creatinine level, sex, age, and weight
of the subject.
24. •
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K (140 – age) Body weight (kg)
GFR (ml/min) = ──────────────────
Serum creatinine (mol/L)
where K is a constant that varies with sex:
1.23 for male 1.04 for females.
The constant K is used as females have a relatively lower
muscle mass.
Cockcroft-Gault Formulafor
Estimation of GFR
25. Cockcroft-Gault Formula
for Estimation of GFR: Limitations
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It should not be used if
Serum creatinine is changing rapidly
the diet is unusual, e.g., strict vegetarian
Low muscle mass, e.g., muscle wasting
Obesity
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Serum Cr is a better KFT than creatinine clearance
because:
Serum creatinine is more accurate.
Serum creatinine level is constant throughout adult life
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Creatinine clearance is only recommended in the
following conditions:
Patients with early ( minor ) renal disease.
Assessment of possible kidney donors.
Detection of renal toxicity of some nephrotoxic drugs.
27. Normal adult reference values:
Urinary excretion of creatinine is 0.5 - 2.0 g per 24 hours in a normal
adult, varying according to muscular weight.
- Serum creatinine : 55 – 120 mol/L
- Creatinine clearance: 90 – 140 ml/min (Males)
80 – 125 ml/min (Females)
A raised serum creatinine is
a good indicator of impaired renal function
But normal serum creatinine
does not necessarily indicate normal renal function as
serum creatinine may not be elevated until GFR has fallen
by as much as 50%
28. ACRU
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Ratios Urine( ACRU )for moderate excretion
range from 3.4 to 34 mg/mmol of Creatinin
e ,and is associated with declining kidney
function.
ACRU ratios higher than34 mg/mmol are
indicative of markedly increased levels of
albumin in urine and have a high predictive
value of more severe kidney disease
29. Urea
• Urea is a waste product of metabolism and
formed in the liver from ammonia released
from deamination of amino acids and
excreted by the kidneys in urine.
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As a kidney function test, serum urea is less reliable
than serum creatinine because:
High protein diet increases urea formation.
Any condition of proteins catabolism (Cushing syndrome,
diabetes mellitus, starvation, thyrotoxicosis) urea
formation.
50 % or more of urea filtered at the glomerulus is passively
reabsorbed by the renal tubules.
32. Procedures
1.Pipette into clean dry test tubes labeled as B ,S
T:
T )ml) S )ml) B )ml) Addition sequence
1 1 1 Working Reagent
(L1+l2)
- - 0.01 Distal water
- 0.01 - Standard
0.01 - - Sample
Mix well and incubate for 5 mins at 37 C°
0.2 0.2 0.2 Chromogen (L3)
Mix well and incubate for 5 mins at 37 C°
2. Measure the abs of S T against blank at 570 nm
33. Calculation
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Urea in mg/dl = × 40
Normal Range :
Serum Urea = 20 - 40 mg/dl
BUN = 7-20 mg/dl
Note : (UREA =BUN ×2.14)
BUN = Urea in mg/dl × 0.467
Abs.
S
Abs.
T
34.
35. BUN
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Urea nitrogen is a normal waste product
created in your liver as it breaks down
certain proteins found in your food. Urea
nitrogen travels through the blood to your
kidneys ,which filter out all but a small
amount. Urea nitrogen exits from your body
when you pee.
If your levels are outside the normal range ,
this might mean either your liver or kidneys
are not working well.
36. Calculation and Normal BUN levels
BUN = blood urea ÷( 2.14)
Or BUN = Urea in mg/dl × (0.467)
Normal range = 7--20 mg/dl
Then we divided the ratios into 4 groups:
,20 ratios ,10 ratios 15-10 ratios .20-15 The history
of the patient was clearly taken and the cause of the
azotemia whether prerenal ,renal or postrenal was noted.
37. High level of BUN
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high-protein diet
Dehydration
Burns
Several medications ,including steroids and
antibiotics
Pregnancy
Stress
An inability to pee due to a blockage in your urinary
tract
Heart attack
Gastrointestinal bleeding( bleeding in your digestive
tract ,such as your stomach ,intestines ,or
esophagus)
Your age
38. Low level of BUN
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Liver disease
Malnutrition( when your diet doesn’t have
enough nutrients or your body can’t
absorb them well)
Overhydration( having too much fluid)
A low-protein diet
41. Introduction
Uric acid is the catabolic product of purines metabolism. It is synthesized
in the liver and excreted through kidney.
Aim of test :
Help diagnose and monitor treatment gou(increase deposition
of uric acid crystals in joints lead to arthritis.)
Confirm the cause of kidney stones may be caused by high
uric acid levels in the body.
Monitoring for medicines that may decrease or increase for
uric acid( chemotherapy or radiation therapy)
43. Proceduers
Reagent and samples :
- Serum, Plasma ( avoid citrated or fluoride plasma) and urine
- Working reagent and STD are ready to use
Procedures :
- Pipette into clean dry test tubes labeled as B ,S and T:
Addition sequence Blank (ml) S (ml) Test (ml)
Working reagent 1 1 1
STD - 0.02 -
Sample - - 0.02
- Mix and incubate at 37Cº for 10 mins and read the OD of test sample and STD against Blank at 505 nm
44. Calculations
Conc. of Uric acid mg /dl = Ab.Test /Ab.STD X 5 (md/dl)
Normal Range:
Serum or Plasma
Male = 3 - 7 mg/dL
Females = 2.5 - 6 mg/dl
Urine = 250 - 750 mg /24 hours
45. Clinical Interpretation
I- Causes of high uric acid (Hyperuricemia ):
Increased production:
Primary :
Lesch-Nyhan syndrome (LNS) is a rare,
inherited disorder caused by a deficiency of the
enzyme essential in purine metabolism
Secondary :
Myeloproliferative disorders
Malignancy
Tumour lysis syndrome
Psoriasis
Alcohol (nucleotide breakdown)
Decreased elimination
Renal failure (acute or chronic)
Lactate or ketoacid excess
(metabolic acidosis)
Drugs, e.g. thiazide diuretics,
low-dose salicylate
Excessive intake of purines
Purine-rich diet (high meat
and seafood diet)
46. Clinical Interpretation
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II- Causes of low uric acid (Hypouricemia) :.
Low purine diet (vegetarians )
Severe liver disease with reduced purine
synthesis
Fanconi syndrome
Overtreatment of hyperuricemia .
cancer chemotherapy
