Renal Investigations Flashcards
Clues to renal disease upon history?
Hematuria Dysuria Fluid overload Flank pain Nocturia Foamy urine Symptoms of uremia Systemic symptoms
What is anasarca?
Extreme generalized edema
What are symptoms of uremia?
Pale conjunctiva Pruritis Pericardial friction rub Confusion Clonus
What sign on physical exam would indicate renal artery stenosis?
Abdominal bruit
What is the single best screening tool for renal disease?
Urinalysis
What is measured in urinalysis?
Color, clarity, turbidity pH Specific gravity Glucose Ketones Blood Protein Microscopic examination of cells, casts, crystals
Which protein is urinalysis most sensitive for?
Albumin
What are two methods of quantifying protein in urine?
- 24 hour urine for protein (Gold Standard)
2. Spot urine sample
What is a urinary cast?
Matrix of Tamm-Horsfall protein
What casts would be suspected in a healthy individual?
Hyaline & fine granular casts
What casts indicate a non-specific abnormality?
Coarse granular casts, waxy casts, fatty casts
What type of cast indicates proliferative glomerulonephritis?
RBC cast
What type of cast would indicate acute tubular necrosis or glomerulonephritis?
Hemegranular casts
What type of cast would indicated an infective/inflammatory process?
WBC cast
What is the most common type of urinary crystal?
Calcium oxalate
What three factors accelerate age-related loss of kidney function?
- Hypertension
- Smoking
- Abnormal glucose metabolism
What is creatinine?
Product of normal muscle metabolism cleared by filtration (95%) and secretion (5%)
What is creatinine clearance?
Estimate of glomerular filtration rate
What is the Cockcroft-Gault formula?
Measurement of creatinine clearance
CrCl (mL/min) = [(140-age) x IBW (kg)]/ serum creatinine (micromol/L)
What is the correction factor for males in the Cockcroft-Gault formula?
Multiply by 1.2
When is the MDRD (Modification of Diet in Renal Disease) formula helpful?
When GFR < 60ml/min
How is kidney biopsy performed?
Percutaneously through the back +/- direct visualization with ultrasound or CT
What is the biggest risk of kidney biopsy?
Hematuria
When would you expect a false positive urine dipstick for protein?
Highly concentrated urine samples
Hematuria, RBC casts, dysmorphic RBCs, proteinuria - Diagnosis?
Proliferative glomerulonephritis
Isolated proteinuria - Diagnosis?
>500mg/24hours = renal disease >3g/24hours = non-proliferative glomerulonephritis
Heme or coarse granular/epithelial casts with free epithelial cells - Diagnosis?
Acute tubular necrosis
Isolated hematuria - Diagnosis?
Mild glomerular damage or urologic cause
Isolated pyuria - Diagnosis?
Interstitial infection or nephritis
Negative urinalysis in setting of renal failure - Diagnosis?
Pre-renal or post-renal disease
What charge of protein is is the urine dipstick good at detecting?
Negatively charged proteins
List the three types of proteinuria
- Glomerular
- Tubular
- Overflow
What is the rule of thumb about serum creatinine and GFR?
Every time serum creatinine doubles, GFR drops by 50%
