URINALYSIS AND RPFT

Sir. Stymass Kasty
SOKOINE UNIVERSITY OF AGRICULTURE(SUA)
MOROGORO-TANZANIA
RENAL FUNCTION TEST-1
URINALYSIS AND RENAL
PLASMA FLOW TEST
April 26, 2018Sir. Stymass Kasty
1

CONTENTS
1.Introduction to Renal
Function Tests (RFT).
2.Urinalysis.
3.Renal plasma flow test.
4.Conclusion.
5.References.
2

1. INTRODUCTION TO RFTs
• Renal function tests are common lab tests used
to evaluate how well the kidneys are working.
• Biochemical Tests of Renal Function classified based
on
Urinalysis
 Measurement of renal blood flow (RBF) or
effective renal plasma flow (ERPF)
Measurement of GFR
Clearance tests
Plasma creatinine
Tubular function tests
3

2.URINALYSIS
URINALYSIS is the macroscopic (chemical
and physical) and microscopic examination of
urine. It involves a number of tests to detect and
measure various compounds that pass through the
urine.
Urinalysis is one of the commonest
biochemical tests performed outside the
laboratory.
4

2.URINALYSIS
Why URINALYSIS?
 General evaluation of health
• Diagnosis of disease or disorders of the kidneys or
urinary tract
• Diagnosis of other systemic disease that affect kidney
function
• Monitoring of patients with diabetes
• Screening for drug abuse (eg. Sulfonamide or
aminoglycosides)
5

2.URINALYSIS
What to look for?
Urinalysis consists of the following
measurements: –
• Macroscopic or physical examination
• Chemical examination
• Microscopic examination of the sediment
• Urine culture
6

2.URINALYSIS
Physical Examination of urine
I) Colour:
Freshly excreted urine is colorless to straw colored
The normal color of urine is due to the presence of
pigment urochrome
Trances of other substances, such as- Uroerythrin,
urobilin, uroporphyrin and coproporphyrins also
contribute to the color of urine
7

2.URINALYSIS
Physiological Variations of Urine colour
Dark yellow _______Concentrated urine-
Mild dehydration
Vitamin B complex
therapy
Orange ___________Drug induced
Pinkish ___________ Excessive beet root
intake
8

2.URINALYSIS
II) Volume of urine:
 Normal volume-800-2,500 ml/day with an average
of 1500 ml/day.
 Approximately 500 ml/day is the minimum volume
of urine needed in normal health to remove waste
products
 The volume of urine is affected by-
• Fluid intake
• Fluid loss
• Type of diet
• Cardio-vascular status and
• Renal functions
9

2.URINALYSIS
Variations in volume of urine excreted
• A) Polyuria: Polyuria implies an increased volume of
urine excreted per day, generally volume of urine
exceeding 2,500 ml/day is termed as Polyuria.
• Conditions causing Polyuria
• Diabetes mellitus (Melichuria)
• Diabetes Insipidus
• Late stage of chronic glomerulonephritis
•Drug induced- Diuretics
• Alcohol
• Compulsive polydipsia
10

2.URINALYSIS
B) Oliguria- Volume of urine less than 500 ml/day
is termed oliguria.
Conditions causing oliguria
• Fever
• Diarrhea (loss of fluid from extra renal sites)
• Severe edema
• Acute nephritis
• Early stage of acute glomerulonephritis
• Cardiac failure and hypertension (reduced
circulatory volume)
11

2.URINALYSIS
C) Anuria- Complete cessation of urine or
volume of excreted urine less than 100 ml/day.
• Conditions causing Anuria
• Acute tubular necrosis
• Blood transfusion reaction
• Surgical shock
• Bilateral renal stones
• Sulphonamide therapy
12

2.URINALYSIS
III)Specific Gravity:
The specific gravity indicates the concentrating ability
of the kidneys.
IT IS CRUDE ESTIMATION OF URINARY
OSMOLALITY
• In normal health the urinary specific gravity ranges
between 1.016-1.025, the average being 1.020.
• The specific gravity is affected by-
• Volume of urine excreted and
• The amount of solids present in the urine
13

2.URINALYSIS
Variations in specific gravity of urine
A) Low specific gravity- 1.016 or less
Conditions
• Compulsive polydipsia
• Diabetes Insipidus
• Glomerulonephritis
• Pyelonephritis
14

2.URINALYSIS
B) High specific gravity of urine- 1.025 or more
Conditions causing high specific gravity of urine
• Severe dehydration
• Nephrotic syndrome (Due to proteinuria)
• Diabetes mellitus ( Due to glycosuria)
• Adrenal insufficiency(Excess of sodium in urine)
• Congestive heart failure
• Hepatic diseases
• Extra renal water losses (fever, vomiting and
diarrhea)
15

2.URINALYSIS
C)Fixed specific gravity (Isosthenuria)
Fixed specific gravity is seen in chronic renal
failure.
• Specific gravity of urine is based on tubular
function
• In the late stages of chronic renal failure, kidneys
fail to concentrate or dilute urine, which has a
constant specific gravity ranging between 1.008-
1.012(average 1.010) same as that of plasma.
16

2.URINALYSIS
Measurement of specific gravity
The specific gravity is measured by Refractometer
17

2.URINALYSIS
IV) Odor of urine
Normal urine has an aromatic odor
Variations
• Ammoniacal Odor- On keeping sample for a
long time
• Acetone like Odor- Ketonuria such as Diabetic
ketoacidosis or starvation
• Foul smell due to bacterial infections
18

2.URINALYSIS
V) pH
Normal urine is acidic, pH ranges between 4.5-8.0 with a
mean of 6.0 in 24 hours
Variations of urinary pH
A) Acidic urine Physiologically,
It is found after
• A protein rich diet
• Heavy exercise
• Pathologically , It is found in conditions of acidosis, such
as
• diabetic ketoacidosis, respiratory acidosis, and high fever
(break down of tissue proteins)
19

2.URINALYSIS
Variations of urinary pH
• B) Alkaline pH
Physiologically it is found after
• Heavy meals
• Diet rich in citrus fruits
• Excessive intake of milk and antacids
Pathologically, it is found in-
• Urinary tract infections
• Conditions of alkalosis
20

2.URINALYSIS
• Urinary pH is measured by-
 pH papers.
 Litmus papers.
Multitrix sticks
(disposable strips).
21

2.URINALYSIS
Chemical methods
USING DISPOSABLE STRIPS
• Urinalysis is commonly measure the following
indices in urine sample;
▫ Specific gravity and osmolality
▫ pH
▫ Glucose
▫ Protein
▫ Urinary sediments
22

2.URINALYSIS
•Biochemical testing of urine use commercially
available disposable strips. Urine Dipstick
Glucose
Bilirubin
Ketones
Specific Gravity
Blood
pH
Protein
Urobilinogen
Nitrite
Leukocyte Esterase
23

2.URINALYSIS
PRINCIPLE
When the strip is manually immersed in the
urine sample , the reagents react with a specific
component of urine in such a way that to form
color which is proportional to the conc. of the
component being tested for.
24

2.URINALYSIS
Procedure to test a urine sample :
fresh urine is collected into a clean dry
container
the sample is not centrifuged
 the disposable strip is briefly immersed in
the urine specimen;
The colour of the test areas are compared
with those provided on a colour chart ( next
slide )
25

2.URINALYSIS
multistix testing of urine sample
(a) strip immersed in urine, (b) excess urine removed
(c) Test strip is compared with colour chart on the bottle.
26

2.URINALYSIS
Microscopic examination of
the sediment.
URINE SEDIMENTS.
- Microscopic examination of sediment from freshly passed
urine involves looking for cells, casts, fat droplets .Example,
- Red Cell casts could indicate glomerular disease
- Leucocytes in the urine suggests acute inflammation and
the presence of a urinary tract infection.
27

2. URINALYSIS
 The urine
specimen is
centrifuged
and the liquid
portion is
poured off.
28

2.URINALYSIS
• The concentrated cellular sediment is then placed
on a microscope slide, covered with a coverslip and
viewed under a microscope.
• A variety of normal and abnormal cellular elements
may be seen in urine sediment such as:
▫ Red blood cells
▫ White blood cells
▫ Mucus
▫ Various epithelial cells
▫ Various crystals
▫ Bacteria
29

2.URINALYSIS
 Red blood cells
 presence of a few
is normal
 higher numbers
are indicator of
renal disease
 result of bleeding
at any point in
urinary system
40x objective
30

2.URINALYSIS
 White blood
cells
 a few are normal
 high numbers
indicate
inflammation or
infection
somewhere along
the urinary or
genital tract
40x objective
31

2.URINALYSIS
 Mucus
 look like long,
ribbon-like threads
 common finding in
urine sediment
 secreted by glands in
the lower urinary
tract
40x objective
32

2.URINALYSIS
Epithelial cells
cells are large and flat
 normal cells that
line the urinary
and genital tract
or renal tubules
40x objective
33

2.URINALYSIS
 A variety of
normal and
abnormal
crystals
may be
present in
the urine
sediment.
34

3.RENAL PLASMA FLOW TEST
• RENAL PLASMA FLOW
▫ Is the volume of plasma that reaches the kidneys
per unit time.
▫ Tests to Measure Renal Plasma Flow / or effective
renal plasma flow (ERPF) are:
I. Para-Amino hippurate (PAH) test
II. Filtration fraction
35

A. MEASUREMENT OF RENAL PLASMA FLOW.
PARA-AMINO HIPPURATE (PAH)
Is filtered at the glomeruli and secreted by the
tubules. At low blood concentrations of plasma, PAH is
removed completely during a single circulation of the blood
through the kidneys. Tubular capacity for excreting PAH of
low blood levels is great. Thus, the amount of PAH in the
urine becomes a measure for the value of plasma cleared of
PAH in a unit time.
36

PARA-AMINO HIPPURATE TEST OR
PAH CLEARANCE
• Since the Renal plasma flow is given by the Fick
principle
• Where,
- Pa arterial plasma
concentration of the substance,
- Pv is its venous plasma conc.,
-Ux is its urineconcentration,
and V is the urine flow rate
37

• Values of Pv are difficult to obtain in patients. In
practice, PAH clearance is used instead.
Accordingly, the venous plasma concentration of
PAH is approximately zero (PAH at low doses, is
completely cleared from the blood during a
single pass through the kidney) and then__
• For PAH
which is the equation
for renal clearance
38

IMPORTANT;
Since the venous plasma concentration of
PAH is not exactly zero (in fact, it is usually 10% of
the PAH arterial plasma concentration), eRPF
usually underestimates RPF by approximately
10%. This margin of error is generally acceptable
considering the ease with which PAH infusion
allows eRPF to be measured.
39

B.FILTRATION FRACTION
The filtration fraction (FF) Is the fraction of plasma passing
through the kidney which is filtered at the glomerulus and is
obtained by dividing the inulin clearance by the PAH
clearance.
Example;
Assume GFR = 125 and RPF = 594, then the
Filtration Fraction =125/574 = 0.217 (21.7%)
Normal range: 0.16 to 0.21 in an adult
40

INTERPRETATIONS
The FF tends to be normal in early essential
hypertension, but as the disease progresses, the decrease in
RPF is greater than the decrease in the GFR. This produces
an increase in FF.
i. In the malignant phase of hypertension: These
changes are much greater, consequently the FF rises
considerably.
ii. A rise in FF is also observed early in congestive
cardiac failure.
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• ALSO:
▫ Catecholamines (Norepinephrine and
Epinephrine) increase the filtration fraction by
vasoconstriction of afferent and efferent
arterioles, which is possibly activated by alpha 1
adrenergic receptors.
▫ Severe haemorrhage will also result in an
increased filtration fraction.
42

4. CONCLUSION
▫ Renal function tests should be ordered on patients
who are at risk of kidney disease.
• They are used to monitor renal function, stage
chronic kidney disease, classify acute renal
failure, and dose medications.
• Knowing the various tests available and the
idiocrancies of each test will provide patients
with a better health care plan and monitoring.
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5.REFERENCES
1. Boron, Walter F., Boulpaep, Emile L.
(2005). Medical Physiology: A Cellular and
Molecular Approach. Philadelphia, PA:
Elsevier/Saunders. ISBN 1-4160-2328-3,
2. Eaton, Douglas C., Pooler, John P.
(2004). Vander's Renal Physiology (8th
edition ed.). Lange Medical Books/McGraw-
Hill. ISBN 0-07-135728-9.
3. MN Chatterjea, Rana Shinde.(2012, Text
book of Medical Biochemistry. 8th Edition.
44

Email.Stymass1@gmail.com_
Contact 0755527871
45

URINALYSIS AND RPFT

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