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.
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
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
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
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