Renal function test

1. RENAL FUNCTION TEST
Khadga Raj Aran
M. Pharm, Ph.D. Research scholar
(Pharmacology)
DEPARTMENT OF PHARMACOLOGY,
ISFCP, MOGA, PUNJAB- 142001

2. INTRODUCTION
phrons.
 The kidneys are two bean shaped organs lying on each side of the vertebral column slightly above the
level of umbilicus.
 Each kidney contains approx. 1 million
 A Nephron consist:-
 OUTER LAYER
(the cortex)
-glomeruli
-PCT & DCT
-CD
 INNER LAYER
(the medulla)
-Straight portion of tubules
-LOH
-vasa recta
-terminal CD

3. FUNCTION OF KIDNEY
1 Excretion of waste products: Kidney excretes metabolic waste products
such as urea, creatinine and uric acid.
2 Maintans homeostasis :Kidney maintains water and electrolyte balance
with the help of antidiuretic hormone (Water Balance ) and renin – angiotensin –
aldosterone mechanism (Electrolyte balance) and maintains acid base balance by
reabsorbing sodium bicarbonate .

4.  Formation of urine as the waste product
 Excretion of end products of protien and nucleic acid metabolic substances
 Regulation of salt & water balance
 Regulation of acid-base balance
 Production of Hormones

5. Why test renal function?
 To asses the functional capacity of kidney.
 Early detection of possible renal impairment.
 Severity and progression of the impairment.
 Monitor response to treatment.
 Monitor the safe and effective use of drugs which
are excreted in the urine

6. When should we assess renal function?
 Older age
 Family history of Chronic Kidney disease (CKD)
 Decreased renal mass
 Low birth weight
 Diabetes Mellitus (DM)
 Hypertension (HTN)
 Autoimmune disease
 Systemic infections
 Urinary tract infections (UTI)
 Nephrolithiasis
 Obstruction to the lower urinary tract
 Drug toxicity

7.  1. Urineanalysis
 2. Tests for assessment of glomerularfunction
 3. Tests to measure renal plasmaflow
 4. Tests for assessment of tubularfunction

8. Physical
examination
Chemical
examination
Microscopic
examination

9. MACROSCOPIC EXAMINATION
 Color
Normal-pale yellow in color due to pigments urochrome,urobilin, Cloudiness may be caused
by excessive cellular material or protein, crystallization or precipitation of salts upon standing at
room temperature or in the refrigerator.
If the sample contains many red blood cells, it would be cloudy as well as red.
Normal Deep yellow---- conc. Of urochrome pigment
Red Blood, Hemoglobulinuria, myoglobinuria, beetroot
Orange rifampicin
Yellow Concentrated urine, ( dehydration, jaundice, B complex,
sulfasalazine)
Green Methylene blue
Black Severe hemoglobinuria, methyldopa
Brown Bilirubin, phenothiazides

10.  VOLUME
Normal- 800 ml -2.5 L/day
 Oliguria- Urine Output < 300ml/day
Seen in
 Acuteglomerulonephritis
 RenalFailure
 Polyuria- Urine Output > 2.5 L/day
Seen in
 Increased wateringestion
 Diabetes mellitus andinsipidus.
 Anuria- Urine output < 100ml/day
Seen in renal shut down
 pH
 Urine pH ranges from 4.5 to 8
 Normally it is slightly acidic lying
between 6 – 6.5.
 After meal it becomes alkaline. 4
resulting in alkaline reaction.

11. Principles of Chemical Tests
pH –
The pH is a measure of the degree of acidity or alkalinity of the urine.
A pH below 7 indicates an acid urine; pH above 7 indicates an alkaline
urine. Normal, freshly-voided urine may have a pH range of 4.5 - 8.0.
The pH of urine may change with diet, medications, kidney disease,
and metabolic diseases such as diabetes mellitus. Colors on the pH
reagent pad usually range from yellow-orange for acid pH to green-
blue when pH is alkaline.
Protein - Protein in the urine is called proteinuria. This is an important
indicator of renal disease, but can be caused by other conditions as
well. At a constant pH, the development of any green color on the
protein reagent pad is due to the presence of protein. Colors range
from yellow for negative to yellow-green or green for positive.

12. Glucose - The presence of glucose in urine is called glycosuria. This
condition indicates that the blood glucose level has exceeded the renal
threshold. This condition may occur in diabetes mellitus. The reagent
strip is specific for glucose and uses the enzymes glucose oxidase and
peroxidase, which react with glucose to form colors ranging from green
(low concentration) to brown (high concentration.
Ketone – Ketones present in the blood is known as ketonuria. This
occurs when the body metabolizes fats incompletely causing ketones to
be excreted in the urine. Ketonuria may be present in diabetes, starvation
or fasting. Since ketones will evaporate at room temperature, urine
should be tightly covered and refrigerated if not tested promptly.
Bilirubin – Bilirubin in the urine is known as bilirubinuria.
Bilirubin is a breakdown product of hemoglobin which produces an
extremely yellow to amber color in urine and may be an indication of
liver disease, hepatitis or bile duct obstruction.

13. Substance Reference Ranges (aka Normal Values)
pH 5.5 - 8.0
Protein Negative
Glucose Negative
Ketones Negative
Bilirubin Negative
Blood Negative
Leukocytes Negative
Nitrites Negative

14. 2. TEST FOR ASSESSMENT OF GLOMERULAR FILTERATION
Renal clearance test
Blood urea and
serum creatinine
Proteinuria Haematuria
RFT

15. Renal clearance of a substance is defined as the volume of plasma
from which the substance is completely cleared by the kidneys per
minute
Clearance test
• Creatinine clearance
• Urea clearance
• Inulin clearance
1. Creatinine clearance test: A test that helps determine whether the
kidneys are functioning normally. Creatinine is produced from the
metabolism of protein as when muscles burn energy.
• Creatinine freely filtered in the glomerulus
• Not reabsorbed by the tubules

16. Creatinine Clearance =U x V
P
U = Urinary Creatinine(mg/L)
P = Plasma creatinine (mg/L)
V = Volume of urine per minute
• ↓ Creat. Clearance is very sensitive indicator of decreased
GFR
• ↓ GFR may be caused by Acute or Chronic damage to glomerulus
or any of its components
• ↓ Blood flow to glomerulus may also produce decreased
creat.clearance

17. 2. Urea Clearance Test
Expression of the number of ml of blood or plasma which are completely
cleared of urea by the kidney per minute.
Maximum clearance: when urine output is 2 ml/min.
𝑼×𝑽𝑷
U = concentration of urea
in urine (in mg/dL)
V = Volume of urine in
ml/min
P = Concentration of urea in blood (in mg/dL)

18. Interpretation of results for urea clearance
 Urea clearance of 70% indicates of normal functioning.
 In Acute Renal Failure: Urea clearance is usually less than ½.
 In Chronic Nephritis: Urea clearance falls progressively and reaches to ½ or less of
the normal before the blood urea conc. Begins to rise.
 In Terminal Uraemia: Urea clearance falls to about 5% of the normal value.
 In Nephrotic Syndrome: Urea clearance is usually normal until the onset of renal
insufficiency sets in and produces same change as chronic nephritis.
 1. If Urea clearance is >70%, renal function is normal.
 2. If Urea clearance is between 40-70%, renal function is mildly impaired.
 3. If Urea clearance is <20%, renal function is severely impaired.

19. 3. Inulin Clearance Test
• Method of choice when accurate determination of GFR is required.
• Inulin is polysacharide of Fructose. Freely filtered
by glomerulus
not reabsorbed
not secreted or metabolically altered by the renal tubule.
• Normal value : 120 ml/mt.
Disadvantages : need for its IV adminstratio
technically difficulty of analysis

20. 3. Tests to measure renal plasma flow
i. Para-amino hippurate (PAH)
PAH clearance is a method used in renal physiology to measure
renal plasma flow, which is a measure of renal function.
PAH is completely removed from blood that passes through the
kidneys (PAH undergoes both glomerular filtration and tubular
secretion), and therefore the rate at which the kidneys can clear PAH
from the blood reflects total renal plasma flow.
 PAH is filtered at glomeruli & secreted by the tubules.
 PAH is completely removed during a single blood circulation through
kidneys at low blood conc.(2mg or less/100ml) of plasma.
 PAH clearance at low blood levels measures renal plasma flow (RPF).

21. ii) Filtration Fraction(FF)
 Filtration fraction is the fraction of plasma passing through the
kidneys which is filtered at the glomerulus and is obtained by
dividing the Inulin clearanceby PAH clearance.
 NORMAL
RANGE:-
0.16 to 0.21 in an adult.
 FF= GFR
RPF
Glomerular filtration rate (GFR) to the renal
plasma flow (RPF)

22. 4. Test to Measure Tubular Functions
A. Urine concentration test.
Determines the concentration ability of renal tubules.
Procedure
1. No food or water after meal at 6 PM.
2. Next day at 7 AM, collect urine and discard it.
3. At 8 AM, collect urine specimen.
4. Measure the osmolality of urine
Interpretation
Urine osmolality >850 mOsm/kg water (renal
concentration ability normal).

23. Lower osmolality of urine indicates
Chronic renal failure
Acute tubular necrosis
Nephrogenic diabetes insipidus etc.
B. Phenolsulphthalein (PSP) test
Patient is given 600 ml water initially. Phenolsulphthalein test dye 6 mg
in 1 ml saline is given intravenously and urine samples are collected
at 15, 30, 60, 120 minutes.
If the 15 minute urine contains 25% or more, the test is normal.
If it is lesser than 25%, it indicates impaired renal excretory function.

24. C. Urine Dilution
• Urine dilution test is done to assess the ability of kidneys to eliminate
water.
• In Urine Dilution test, after emptying the bladder, 1200 ml of water is
given. Urinary specific gravity should be fall to 1.005or osmolality
lesser then the 100ml/kg
• Urine collected hourly for next 4 hours
• In renal tubular disease, there will be a fixed specific gravity
• This test is not advisable for patients with adrenal insufficiency

25. D. Urine Acidification
• Urine acidification test is done to check the ability of kidney
to produce acidic urine which is the function of tubules.
• To excess the ability of kidney to reabsorb bicarbonate and
excrete hydrogen ions.
• Ammonia Chloride (100mg/kg) in gelatine capsule is given
Urine is collected hourly for 8 hours. pH of urine normally
falls between 4.6 to 5.3
• In patients with renal tubular acidosis , ph does not fall below
5.3 even after dose of ammonium chloride

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