W14 - Assessment of renal function Flashcards
What, by consensus, is the best measure of kidney function?
A.Serum creatinine itself
B.Serum creatinine and urea
C.Urine protein:creatinine ratio
D.Glomerular filtration rate
E.Cystatin C
D. GFR
What is a typical GFR
Age related decline of GFR is approximately ______ per year
120 ml/min = normal (7.2L/hour)
•Age related decline approximately 1ml/min per year
______ clearance is gold-standard measure of GFR
inulin = the perfect marker = freely filtered, not processed by tubular cells
but is only a research tool
Which factor(s) limit(s) the use of serum creatinine as a marker of GFR?
A.It is influenced by intake of fat
B.It is lower in the black population
C.It is related to muscle mass
D.It is reabsorbed by the renal tubules
E.All of the above
C. It is related to muscle mass
Generation of serum creatinine is not equivalent in different individuals. Name 4 factors that affect creatinine production
- Muscularity (more muslce = more creatinine)
- Age (younger = more creatinine)
- Sex (male = more creatinine)
- Ethnicity (Black = more creatinine)
True or false:
A spot urine measurement to quantify proteinuria can be done instead of a 24 hour urinary collection?
True
Which of the following is true regarding urine dipstick testing?
A.If the dipstick is negative for blood it reliably excludes haematuria
B.Haematuria is the only cause of a positive dipstick test for blood.
C.You can reliably exclude bacteriuria if the urine dipstick is negative for nitrites
D.The urine dipstick detects Bence Jones proteins
E.Glycosuria detected by the dipstick means the patient has diabetes.
C.You can reliably exclude bacteriuria if the urine dipstick is negative for nitrites
A 50 year old, known alcoholic, presents generally unwell, seemingly intoxicated, with acute kidney injury. Urine microscopy reveals calcium oxalate monohydrate crystals, what diagnosis do you suspect?
Ethylene glycol poisoning - erythene glycol is in antifreeze, when metabolised in body it produces highly toxic metabolites. it shows these signs of alcohol intoxication; is rapidly distributed around the body.
due to its biochemistry and its rapid conversion, you get these calcium oxalate monohydrate (spindle, oval, or dumb-bell shape) crystals. if you see these in someone who seems intoxicated, think ethylene glycol poisoning.
What 6 things can you check for in a urine disptick test
- pH
- Specific gravity
- Proteins (not BJPs)
- Blood (zero, trace, +1 to +4)
- Leucoyte esterase
- Nitrite (detects bacteria, esp G-)
Urine microscopy - what 5 things can you check for?
Examine sediment for:
- Cyrstals (i.e. kidney stones, eythele glycol ingestion)
- Red blood cells (i.e. glomerular damage, malignancy, UTI)
- White blood cells (i.e. UTI)
- Casts (i.e. glomerular dysfunction in Red cell casts)
- Bacteria (i.e. UTI)
You admit a 28 year old man who you suspect has a renal stone, what is your first choice of imaging?
A.Plain KUB
B.CT
C.Ultrasound KUB
D.IVU
E.MRI
B. CT
