Download - S4 Renal Function Test
Renal Function Test
Dr C. L. [email protected] Medicine
IMU Clinical School
23rd Nov 2010, IMU Bukit Jalil
Learning outcomes
• Describe common tests on urine and compare between urine dipstix and microscopy for diagnosis of renal diseases.
• Compare blood urea and creatinine levels in the assessment of renal impairment.
• Identify different ways of imaging renal tracts and their common abnormalities.
• Describe how renal biopsy is done.
Urine test
• Urinalysis– Quantity
– Colour
– Specific gravity*
– pH*
– Protein*
– Others (ketone, glucose, bilirubin)*
• Microscopy– RBC**
– WBC**
– Cast
– Crystal
– Bacteria**
* Can be measured by dipstix (e.g. Combur-10)** Can be tested using dipstix (indirectly)
Urine volume and colour• Urine volume: 700 – 2500 ml/day
(Glomerular filtrate = 180 L/day)– Oliguria: <400 ml/day
– Anuria: <100 ml/day
• “Smoky” urine - small amount of blood (e.g. AGN)
Patient 1: A 50 year-old man with severe left loin pain and haematuria
Patient 2: A 10 year-old girl with facial puffiness, hypertension and
“cloudy urine”
Patient 3: A 45 year-old man who ate jering
• A healthy 45-year-old Sarawakian man presented with colicky left loin pain, dysuria, frank haematuria and foul smelling urine a day after ingesting jering. He developed oliguria and was anuric by the 3rd day.
• Serum creatinine 176 μmol/L, urea 18 mmol/L, potassium 4.4 mmol/L and bicarbonate 21.1 mmol/L.
Abnormal urine colour may not be due to renal disease
Urine dipstix
• Reagent strips allowing 1 or more tests.
• Semi-quantitative.• Quick screening test.• Less accurate when
compared with microscopy.
blood
Renal concentrating ability
• Normal SG: 1.002 – 1.025• Proportional to urinary concentration of
urea and sodium• Renal concentrating ability is normal if SG
> 1.018• In CRF, SG fixed at 1.010 (= glomerular
filtrate)
Renal acidifying ability
• Normal pH < 7.0
• Renal acidifying ability is normal if urine
pH < 5.5
• Acidosis occurs only in advanced CRF.
• In renal tubular acidosis, urine pH exceed 5.4 after given ammonium chloride (i.e. failure to acidify the urine following an oral acid loading challenge).
Two children with facial puffiness
Acute post-streptococcal glomerulonephritis
4 year-oldBP 80/40 mmHg (normal)UrinalysisProtein: 3+Blood: negativeWBC: negativeRBC: negative
10 year-oldBP 150/100 mmHg (high)UrinalysisProtein: 2+Blood: positiveWBC: 1+RBC: 2+
Nephrotic syndrome Nephritic syndrome
ProteinuriaNormal Proteinuria “Massive” proteinuria
24 H urine protein <300 mg/day >300 mg/day >3.5 g/day (nephrotic)
Urine protein dipstix: negative to trace ≥1+ ≥3+
Normal Microalbuminuria Albuminuria
Urine protein dipstix: negative negative/trave ≥1+
24 H urine albumin <30 30-300 >300 mg/day
ACR (mg/mmol) M: <2.5 M: 2.5-30 F: <3.5 F: 3.5-30
ACR=Albumin:Creatinine ratio
Urine microscopy
Urine microscopy - blood
• Overtaken by automated test with dipstix
• Centrifuged urine has– < 1 rbc/hpf– < 5 wbc/hpf
• Dipstix can’t differentiate between haematuria and haemoglobinuria
www.udel.edu/medtech/mclane/csmain.html
Colour: AmberProtein: 1+Blood: 2+WBC: 1+RBC: 2+
A 56-y.o. woman with oedema, decreased urine volume, fever, general malaise and abdominal pain
WBC: 5-10/hpf RBC: 10-20/hpf Celluar casts: 0-2/lpf
Dysmorphic RBC = glomerular bleeding (GN)
High power light microscopy
A Normal rbcB-F Dysmorphic rbc(Scanning electron microscopy)
Acanthocytes – specific for glomerular bleeding
Phase contrast microscopyx1450 x3250
http://content.nejm.org/cgi/ijlink?linkType=FULL&journalCode=nejm&resid=334/22/1440
Urine microscopy – WBC, bacteria
• Pyuria – infection or injury of renal tract.
• Bacteria can be detected by gram stain.
• Most UTIs are caused by gram –ve bacteria (E. coli)
• Dipstix detects WBC by leucocyte esterase reaction.
• Positive nitrite in dipstix suggests significant bacteriuria (>105 organisms/mL)
• Gram –ve bacteria reduced nitrate to nitrite.
Microscopy – casts
Hyaline cast Granular cast Waxy cast
Red cell cast White cell cast Broad cast
Microscopy – casts
• Hyaline cast – normal
• Red cell cast – GN
• White cell cast – GN, pyelonephritis
• Epithelial cast – acute tubular necrosis
• Broad cast – chronic renal failure
• Granular cast, waxy cast – renal disease
Microscopy – crystals
Ammonium magnesium Phosphate crystals
Calcium oxalate crystals
Cystine crystals Urate crystals
“normal crystals”
“abnormal crystals”
Can I trust the test result?
• Urine collection: early morning midstream clean catch urine.
• False positive: blood in urine may be due to contamination (menstruation in female).
• False negative: nitrite negative may be due to dilute urine.
Positive test = Disease present?
Disease
present
Disease
absent
Test positive TRUE POSITIVE
FALSE POSITIVE
Test negative FALSE NEGATIVE
TRUE NEGATIVE
Estimation of GFR
• Normal GFR is 70-170 ml/min (varies with sex, weight and surface area).
• Blood urea and creatinine levels are good substitutes in clinical practice
Blood urea
• Normal range is 2.5 – 6.6 mmol/L.
• Its level varies with protein intake.
• Raised by dehydration, fever and GI haemorrhage.
• 50% of filtered urea is reabsorbed.
• Very high level correlates well with uraemia.
Serum creatinine
• Normal range is 62 – 124 mol/L (0.7-1.4 mg/dL)
• Level less affected by extrarenal factors.• Serum creatinine correlates better with GFR
than blood urea.• Creatinine clearance declines by 1 ml/min/y
over the age of 40 (aging process).
Reciprocal relationship between creatinine clearance and plasma creatinine concentration
GFR calculatorhttp://www.kidney.org/professionals/KDOQI/gfr_calculator.cfm
Classification of CKDStage GFR Description Management
I 90+Normal Renal Function(but urinalysis, structural abnormalities or genetic factors indicate renal disease)
Observation and control of blood pressure
II 60-89
Mildly reduced renal function(Stage 2 CKD should not be diagnosed on GFR alone - but urinalysis, structural abnormalities or genetic factors indicate renal disease)
Observation, control of blood pressure and cardiovascular risk factors
IIIa 45-59 Moderate decrease in renal function, with or without other evidence of kidney damage
Observation, control of blood pressure and cardiovascular risk factors
IIIb 30-44 Moderate decrease in renal function, with or without other evidence of kidney damage
Observation, control of blood pressure and cardiovascular risk factors
IV 15-29 Severely reduced renal function Planning for end stage renal failure
V <15 Very severe (end stage) renal failure Transplant or Dialysis
Renal profile in a 62 year-old man with type 2 diabetes2009 2010
Sodium 145 146 (135-145)Potassium 3.8 4.3 (3.5-5.1)Chloride 107 102 (95-110)Urea 5.6 9.0 (3.0-9.0)Creatinine 91 146 (60-130)eGFR 78 42 mL/min/1.73m2
A small risein creatinine Leads to a big
drop in GFR
Test your knowledge
• An 80 y.o. nursing home resident is admitted with respiratory tract infection. Her blood test results are:
• Sodium 157 (135–147 mmol/L)
• Urea 30 (2.5 – 6.6 mmol/L)
• Creatinine 150 (62 – 124 mol/L)
• Diagnosis: Dehydration
Imaging
• KUB (Kidney Urinary Bladder)
• IVP (Intravenous pyelography)
• Ultrasound
• CT scan (Computed tomography)
Plain X-ray (KUB)
• Kidneys overly the 12th ribs (renal angle)
• Difficult to visualise because of bowel gas.
• Can detect radio-opaque stone
IVP
• Multiple X-rays with contrast injection.
• Delineate structure and obstruction clearly.
• Note calyceal system and path of ureters.
(1) Right kidney (2) Left kidney (3) Minor calyx (4) Major calyx(5) Renal pelvis (6) Ureter
What is wrong with this KUBNormal KUB
What is wrong with the right IVP
Answer
• KUB• Bilateral staghorn
calculus (“deer horns”).
• Conform to the shapes of calyceal system.
• IVP• Rt hydronephrosis
• Rt ureter partially obstructed at level of L5
• Dilated balloon of Foley catheter in bladder
• “Missing” left kidney – nephrectomy, non-functioning
Ultrasound
• No radiation.• Delineate structure
clearly.• Detect mass lesions,
cysts and hydronephrosis.
• Measurement of kidney size.
CT scan
• Cross-sectional view of various slices of body.
• Delineate structure well.
• Require good knowledge of cross-sectional anatomy
A. external obliqueB. right costal carightilageC. rectus abdominusD. transverse colonE. transverse colonF. ascending colonG. pancreas - headH. duodenum - 2nd partI. renal veinJ. diaphragmK. psoas majorL. renal pyramid
http://iris3.med.tufts.edu/medgross/abl1.htm
Figure 1
Transpyloric plane cuts through the pylorus, the tips of the ninth costal cartilages and the lower border of the first lumbar vertebra.
• The transpyloric plane is clinically notable because it passes through several important abdominal structures. These include:
• the fundus of the gallbladder • the neck of the pancreas • the origins of the superior
mesenteric artery and portal vein • the hila of the kidneys • the root of the transverse
mesocolon • the duodenojejunal junction • the 2nd part of the duodenum • the termination of the spinal cord • the spleen
Polycystic kidneys
CT scanUltrasound
Renal biopsy
• Percutaneous needle biopsy from the lower pole.
• Establish diagnosis – adult nephrotic
• Determine prognosis – renal involvement in SLE
• Interpretation of renal pathology
http://www.niddk.nih.gov/health/kidney/pubs/kidney-biopsy/biopsy.htm
Renal biopsy specimen(a) Renal cortex, note the glomeruli, recognized as round red areas (wet preparation x10). (b) Renal medulla, reddish vasculature is present but no glomeruli seen (wet preparation x10)