MTB Nephrology Flashcards
What are the 3 “best initial tests” in nephrology?
UA
BUN
creatinine
List the 7 components of UA
- protein
- white cells - direct micro examination
- leukocyte esterase - dipstick
- red cells
- specific gravity
- pH
- Nitrites - indicates the presence of gram negative bacteria on dipstick
What is damaged in the kidney when you see severe proteinuria?
glomerular damage
What does Tamm-Horsfall protein refer to? How much protein is this referring to?
Tamm- Horsfall refers to the minimal amount of protein that is secreted by the tubules.
protein levels range form 30-50 mg/hr
note: transient proteinuria is normal in 2-10% of the population
What should be done if prolonged proteinuria occurs in the absence of prolonged standing (orthostatic proteinuria)?
kidney biopsy
What are the 2 methods to determine total amount of protein in a day?
- single protein to creatinine ratio –> this is more accurate.
P/Cr 1 = 1 g/day, 2.5 = 2.5 g/day.
Faster and easier test than 24 hours collection - 24-h urine collection
What does urine dipstick for protein test for?
Albumin only
What is normal level of protein excretion from the kidney?
> 300 mg/24 hours
When assessing protienuria, what is the best initial test, and what is the more accurate test in determining the amount?
best initial test: UA
most accurate determination of protein in urine: protein to creatinine ratio
What can be done to determine the cause of proteinuria?
kidney biopsy
Tiny amounts of protein that are too small to detect on the UA are called what?
microalbuminuria
- this is important to detect in diabetics as long term microalbuniuria leads to worsening renal function in a diabetic pt and should be treated.
What is the best initial medication for any sort of proteinuria in a diabetic pt?
ACE inhibitor
ARB
they will delay the development of renal insufficiency
What test needs to be done in order to detect Bense Jones bodies seen in myeloma?
immunoelectrophoresis
White blood cells in urine indicate what 3 possible etiologies?
- inflammation
- Allergic interstitial nephritis
- infection
Are you able to distinguish between eosinophils and neutrophils on a UA?
NO
What does urinary eosinophils suggest?
allergic interstitial nephritis
Does NSAID niduced renal disease show eosinophils?
NO
What stains detect eosinophils in the urine?
Wright and Hansel - allergic interstitial nephritis
How many RBCs are normally found under hpf in a urinalysis?
> 5
List 7 reasons someone might have hematuria.
- Stones in bladder, ureter, kidney
- coagulopathy
- Infection - cystitis, pyelonephritis
- Cancer - bladder, ureters, kidney
- Trauma
- medications - cyclophosphamide = hemorrhagic cystitis
- Glomerulonephritis
What are 2 causes of false positive test for hematuria?
- hemoglobin
2. myoglobin
If dysmorphic RBCs are identified in the urine, what type of renal disorder is most likely present?
Glomerulonephritis
When would you perform a cystoscopy on a pt with hemauria?
When there is no infection and no prior trauma but there is blood in the urine
Cystoscopy is the most accurate test for the bladder
What disease is associated with the following urinary casts?
- red cell
- White cell
- Eosinophil
- Hyaline
- Broad, waxy
- Granular, muddy brown
- glomerulonephriris
- pyelonephritis
- acute (allergic) interstitial nephritis
- dehydration conentrate the urine and the normal Tamm-Horsfall protein precipitates or concentrates into a case
- chronic renal disease
- Acute tubular necrosis
What is acute kidney injury?
AKA - acute renal failure
decrease in creatinine clearance and sudden rise in BUN and creatinine
- no specific numbers define AKI
What are the 3 classifications of acute kidney injury?
- prerenal azotemia - decreased perfusion
- postrenal azotemia- obstruction
- intrinsic renal disease - ischemia and toxins
List 8 causes of prerenal AKI
- hypotension - shock, sepsis, anaphylaxis, bleed, dehydration
- hypovolemia - bleed,, dehydration diuretics, burns, pancreatitis
- renal artery stenosis - BP is high but the kidney is underperfused
- Relative hypovolemia d/t decreased pump function - CHF, constrictive pericarditis, tamponade
- Hypoalbuminemia
- Cirrhosis
- NSAIDs - constrict the afferent arteriole
- ACE inhibitors cause efferent vasodilation
List 6 causes of postrenal azotemia
- prostate hypertrophy or cancer
- stone in ureter
- cervical cancer
- Neurogenic bladder (atonic)
- Urethral stricture
- Retroperitoneal fibrosis - ho bleomycin, radiation, methylsergide
What is the major force controlling filtration in the kidney?
glomerular hydrostatic pressurein the glomerular capillary
- if pressure in Bowman’s space rises - you cannot filter fluid
- both kidneys must be blocked for creatinine to rise
What is the most common cause of intrinsic renal disease?
acute tubular necrosis from toxin exposure or prolonged ischemia
What are some common causes of intrinsic renal disease?
- acute/allergic interstitial nephritis - from meds like penicillins
- Rhabdomyolysis and hemoglobinuria
- contrast, aminoglycosides, cisplatin, amphotericin, cyclosporine, NSAIDs
- crystals - hyperuricemia, hypercalcemia, hyperoxaluria
- protein -bence jones protein from myeloma
- poststreprococcal infeciton
What is the BUN:creatinine ratio for the 3 different classifications of AKI?
prerenal and postrenal - >20:1
intrinsic 10:1
What is the best initial test for dx AKI?
BUN:creatinine
List 4 best initial tests when the cause of AKI is not know.
- UA (always do this first)
- Urine Na UNa
- Fractional excretion of sodium FeNa
- Urine osmolality
What is the urine osmolality of someone with ATN
isosthenuria - same as blood - 300 mOsm/L
Because the tubular cells normally absorb water from the tubules - they are now damaged in AKI and cannot reabsorb water, therefore the urine osmolality is abnormally low.
What is the effect of dehydration on urine concentration/osmolality?
concentrates urine
What is the effect on urine Na and water concentration in ATN?
When the tubular cells are damaged, they cannot absorb water or Na - so the urine Na concentration will be elevated.
UNa >20
UOsmWater osmolality less than 500
What is the only renal manifestation of someone with sickle cell trait - heterozygous for sickle cell.
No renal concentrating ability. This results in dilute urine/isosthenuria
these pts will continue to produce inappropriately dilute urine despite dehydration
- make sure pt stays hydrated
How does urine specific gravity relate to urine osmolality?
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