This document discusses renal function tests and their importance in assessing kidney function and detecting impairment. It describes various tests including urine analysis, blood tests of creatinine and urea, and glomerular function tests. Common indications for evaluating renal function are listed, such as older age, diabetes, and hypertension. The document also outlines approaches to interpreting test results and diagnosing different kidney conditions like acute injury, nephritic syndrome, and nephrotic syndrome.

1. RENAL FUNCTION TEST
Yousaf khan
Renal Dialysis Lecturer
IPMS KMU

2. 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

3. 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

4. WHAT TO EXAMINE???
Renal function tests are divided into the following:
 Urine analysis
 Blood examination
 Glomerular Function Test

5. URINE ANALYSIS
 Urine examination is an extremely valuable
and most easily performed test for the
evaluation of renal functions.
 It includes physical or macroscopic
examination, chemical examination and
microscopic examination of the sediment.

6. MACROSCOPIC EXAMINATION
Colour
 Normal- pale yellow in colour 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.

7. COLOR OF URINE
Normal Deep yellow---- conc. Of urochrome pigment
Red Blood, Hemoglobulinuria, myoglobinuria, beetroot ( chukandar)
orange rifampicin
yellow Concentrated urine, ( dehydration, jaundice, B complex,
sulfasalazine)
Green Methylene blue
Black Severe hemoglobinuri, methyldopa
Brown Bilirubin, phenothiazides

8. VOLUME
Normal- 800 ml -2.5 L/day
 Oliguria- Urine Output < 300ml/day
Seen in
 Acute glomerulonephritis
 Renal Failure
 Polyuria- Urine Output > 2.5 L/day
Seen in
 Increased water ingestion
 Diabetes mellitus and insipidus.
 Anuria- Urine output < 100ml/day
Seen in renal shut down

9. SPECIFIC GRAVITY
 Normal ranges 1.002 – 1.025
 Varies with quantity of urine
Low SG
 CRF
 diabetes insipidus
 Absence of ADH
 Renal tubular demage
High SG
 Dehydration
 diabetes mellitus
 Albuminuruia
 Acute nephritis

10. PH:
 Urine pH ranges from 4.5 to 8
 Normally it is slightly acidic lying between 6 – 6.5.
 After meal it becomes alkaline.
 On exposure to atmosphere, urea in urine splits
causing NH4
+ release resulting in alkaline reaction.

11. CHEMICAL EXAMINATION
Glucose:
 Diabetes
 Impaired Renal tubular
 False positive or negative – large dose of vitamin C,
tetracycline or levodopa
Ketones:
 Diabetic- diabetic ketoacidosis
 Starvation
Protein:
 Normal protein loss from urine is less than 150mg
/24 hrs.

12. MICROSCOPIC EXAMINATION
White cell:
 More than 10 or more wbc per cm- UTI
 Stone, tubulointestinal nephritis, tuberculosis, papillary necrosis
Red cell:
 2-5 per high power field – hematuria
Cast:
 Cylindrical structure- kidney tubule-coagulation of protein
 Hyaline cast: concentrated urine, fever, diuretic therapy, after
exercise
 Granular cast: found in chronic glomerulonephritis, diabetic
nephropathy and malignant hypertension
 White cell cast: acute pyelonephritis
 Red cell cast: glomerulonephritis
 Epithelial cast: acute tubular necrosis and interstitial nephritis

13. Hyaline cast
Red cell cast
White cell
casts
Granular cast

14. Crystals:
 Uric acid: acid urine, acute uric acid nephropathy
 Calcium phosphate in alkaline urine
 Calcium oxalate: hyperoxaluria, acid urine
Uric acid
Calcium
phosphate Calcium
oxalate

15. BLOOD EXAMINATION
 Done to measure substance in blood that are
normally excreted by kidney.
 Their level in blood increases in kidney dysfunction.
 As markers of renal function creatinine, urea,uric
acid and electrolytes are done for routine analysis

16. SERUM CREATININE
 Most useful clinical test
 Creatinine is the product of muscle metabolism
 50% renal function is lost before creatinine is raise
 Normal range is 0.8-1.3 mg/dl in men and 0.6-1 mg/dl in women
Increases serum creatinine independent of GFR
 Impaired renal function
 Very high protein diet
 Anabolic steroid users
 Vary large muscle mass: body
builders, giants, acromegaly patients
 Rhabdomyolysis/crush injury
 Athletes taking oral creatine.
 Drugs:
• Probenecid
• Cimetidine
Decrease serum creatinine
• Advance age
• Liver disease

17. SERUM UREA
 Produce by liver and end product of protein catabolism
 Freely filtered by the glomerulus and 30-40 % reabsorbed.
Increase serum urea
 Dehydration
 Catabolic state
 High protein diet
 Glucocorticoid
 Tetracycline
Low serum urea
 Liver disease
 Malnutrition
 Low protein diet
 Old age

18. GLOMERULAR FUNCTION TESTS
 Measure the amount of plasma ultra filtered across
glomerular capillaries
 Ability of kidney to filter fluids and various
substance
 Normal GFR is in the range of 115- 125 ml/mint.
 GFR indicate both acute and chronic condition
 Inulin clearance and creatinine clearance are used
to measure the GFR.

19. Stage Description (GFR)
At increased risk
Risk factors for kidney disease
(e.g., diabetes, high blood
pressure, family history, older
age, ethnic group)
More than 90
1
Kidney damage with normal
kidney function
90 or above
2
Kidney damage with mild loss of
kidney function
89 to 60
3a
Mild to moderate loss of kidney
function
59 to 44
3b
Moderate to severe loss of kidney
function
44 to 30
4 Severe loss of kidney function 29 to 15
5 Kidney failure Less than 15

20. CREATININE CLEARANCE:
 GFR= Ccr = {Ucr * Urinary flow rate(ml/min)} / Pcr
 Cockroft Gault Formula

21. CLINICAL MANIFESTATIONS OF RENAL
DISEASE
 Azotemia: Elevation of blood urea nitrogen and
creatinine levels
 Decreased glomerular filtration rate (GFR)
 Intrinsic renal disease or extrarenal causes.
 Prerenal azotemia is encountered-hypoperfusion of
the kidneys – Decrease GFR in the absence of
parenchymal damage.
 Postrenal azotemia results when urine flow is
obstructed below the level of the kidney. Relief of
the obstruction is followed by correction of the
azotemia

22.  Azotemia gives rise - uremia.
 Uremia is characterized not only by failure of renal –But
metabolic and endocrine alteration
 Secondary cause uremic gastroenteritis, peripheral
neuropathy and uremic pericarditis
 Azotemia has three classifications, depending on its
causative origin
 Decrease in the glomerular filtration rate (GFR) of
the kidneys and increases in blood urea nitrogen (BUN)
and serum creatinine concentrations.
 The BUN-to-creatinine ratio (BUN:Cr) is a useful
measure in determining the type of azotemia. A normal
BUN:Cr is equal to 15

23. Prerenal azotemia
 decrease in blood flow (hypoperfusion),
hemorrhage, shock,volume depletion, congestive
heart failure, adrenal insufficiency, and narrowing of
the renal artery.
 The BUN:Cr in prerenal azotemia is greater than
20.
Primary renal azotemia
 intrinsic disease of the kidney, generally the result
of renal parenchymal damage.
 The BUN:Cr in renal azotemia is less than 15
Postrenal azotemia
 Blockage of urine flow in an area below the kidneys
results in postrenal azotemia
 The BUN:Cr in postrenal azotemia is initially >15

24. NEPHRITIC SYNDROME
 Glomerular injury and is dominated by the acute
onset
 hematuria (red blood cells and red cell casts in
urine),
 proteinuria of mild to moderate degree,
 azotemia,
 edema,
 hypertension; it is the classic presentation.

25. NEPHROTIC SYNDROME
 Glomerular syndrome
 proteinuria (excretion of greater than 3.5 g of
protein/day in adults),
 hypoalbuminemia,
 severe edema,
 hyperlipidemia,
 lipiduria (lipid in the urine).

26. RAPIDLY PROGRESSIVE
GLOMERULONEPHRITIS
 Rapidly progressive glomerulonephritis is
associated with severe glomerular injury
 loss of renal function in a few days or weeks.
 Microscopic hematuria,
 dysmorphic red blood cells and red cell casts in the
urine sediment,
 Mild to moderate proteinuria.

27. ACUTE KIDNEY INJURY
 Oliguria or anuria (no urine flow),
 Recent onset of azotemia.
 It can result from glomerular injury (such as rapidly
progessive glomerulonephritis), interstitial injury,
vascular injury (such as thrombotic
microangiopathy), or acute tubular injury.
 Chronic kidney disease,
 prolonged symptoms and signs of uremia, is the
result of progressive scarring in the kidney from any
cause and may culminate in end-stage kidney
disease, requiring dialysis or transplantation.

28. URINARY TRACT INFECTION
 Bacteriuria and pyuria (bacteria and leukocytes in
the urine).
 The infection may be symptomatic or
asymptomatic, and it may affect the kidney
(pyelonephritis) or the bladder (cystitis) only.
 Nephrolithiasis (renal stones) is manifested by renal
colic, hematuria (without red cell casts), and
recurrent stone formation

29. IMAGING TECHNIQUES
 Ultrasound
 Plain X-ray abdomen
 Radionuclide studies
 CT scan
 MRI
 Arteriography and Venography
 Excretion urography
 Antegrade urography
 Retrograde urography
 Renal biopsy

30. ULTRASOUND
 Renal size, shape,
 Hydronephrosis
 Renal Mass
 Poly cystic kidney
 Kidney stone

31. Normal
Kidney
Hydronephrosis
Renal Mass
Poly cystic kidney disease

32. Plain X-ray:
 Renal calcification or radiodense calculi
 Outline of ureters and bladder
Radionuclide Studies:
99mTc- DTPA
 Access GFR when urine collection is difficult or expected inaccurate
 Helpful in the diagnosis of renal artery stenosis
 Localized the site of obstruction
99mTc-DMSA
 Determine the contribution of each kidney to overall renal function.
 Localized infection such as renal abscess

33.  CT SCAN:
 CT scan shows kidney, ureters and surrounding tissue in detail and
is useful in the diagnosis of renal tumors.
 MRI:
 Differentiation between cystic and solid renal masses. MR
angiography of renal arteries is increasingly used to screen for renal
arterial disease.
 Arteriography and Venography
 Excretion urography (IVP )
 Antegrade urography
 Retrograde urography
 Renal BIPSY

34. INDICTION OF RENAL BIOPSY
 Adult nephritic syndrome
 Persistent proteinuria > 1g/24 hr
 Persistent microscopic and macroscopic hematuria
 Systemic disease with renal involvement such as
amyloidosis
 Chronic renal failure with normal size of kidney
 Unexplained kidney failure
 Childhood nephritic syndrome