Assessing Renal Function Flashcards
What are 4 causes of increased blood urea nitrogen?
- Post-prandial
- Dehydration
- GI bleeding
- Catabolic drugs
What are 3 causes of decreased blood urea nitrogen?
- Malnutrition
- Severe burns
- Hepatic dysfunction
Creatinine increases with __1__ and __2__.
- Muscle mass
2. High protein diet
In which 2 breeds are creatinine levels naturally high?
- Birmans
2. Greyhounds
Which is more accurate, BUN or creatinine?
Creatinine
What does SDMA stand for?
Symmetric dimethylarginine
When can SDMA detect renal dysfunction?
At 40% loss of function
Which of the following is influenced by muscle mass: creatinine, BUN, or SDMA?
Creatinine
When does renal azotemic develop?
With 75% loss of function
What are the 4 substances used for clearance assays to measure GFR?
- Inulin
- Iohexol
- Creatinine
- Radioisotopes
What is the easiest and most commonly used substance for clearance assays?
Iohexol
What are 4 indications for using a clearance assay?
- Identifying occult renal failure prior to starting nephrotoxic drugs
- Assessing renal function in non-azotemic PU/PD patients
- Screening patients with familial history of kidney disease
- Investigating discrepancies in BUN and creatinine
What is one benefit to renal scintigraphy?
Ability to measure each individual kidney’s GFR
What are the disadvantages of renal scintigraphy?
- Expensive
- Special facilities
- Limited availability
What are the sources of proteinuria?
- Physiological - fever, seizures, intense physical activity
- Non-urinary - genital tract inflammation (vaginitis, prostatitis), hyperglobulinemia (multiple myeloma), hemoglobinemia (hemolytic anemia)
- Urinary - glomerular disease, uroliths, UTIs, bladder tumors
The glomerulus allows passage of molecules less than ___-___ kDa
67-70 kDa
Resorption of most molecules (glucose, amino acids, HCO3, electrolytes) occurs where within the nephron?
Proximal tubule
What are 2 causes of renal proteinuria?
- Increased loss of glomeruli
2. Decreased reabsorption in tubules
A dip stick can be used to quantify protein loss but primarily detects what?
Albumin
Which has more protein loss: (+) protein with USG 1.040 or (+) protein with USG 1.008?
(+) protein with USG 1.008
What is a normal urine protein/creatinine ratio in the dog?
< 0.5
What is a normal urine protein/creatinine ratio in the cat?
< 0.4
What are the 3 main roles of the renal tubules?
- Water conservation
- Acid/base balance
- Reabsorption of metabolites
What is the renal tubular reabsorption threshold for glucose in the cat?
290 mg/dL
What is the renal tubular reabsorption threshold for glucose in the dog?
180-220 mg/dL
On average, the kidneys filter about ____ litters of water/day.
100 L
Of that 100 litters, less than ___% is lost to the urine.
1%
What is the specific gravity a ratio of?
Ratio of the weight of urine vs. weight of an equal amount of water
What is the isosthenuric range of urine?
1.008 - 1.012
At what concentration is urine equal to the osmolality of plasma?
1.008 - 1.012
What do you call urine with a USG of < 1.008?
Hyposthenuric
What are 4 drugs that cause the urine to be dilute?
- Steroids
- Diuretics
- Colloids
- Anti-epileptics
What are 4 concurrent diseases that might affect the USG?
- Dehydration
- Endocrine diseases (DM, cushing’s, addison’s)
- Electrolyte abnormalities (hypercalcemia)
- Infections (pyometra, pyelonephritis, leptospirosis)
What 3 things does one need to concentrate their urine?
- ADH
- ADH receptors
- Functional kidneys
After running a water deprivation test and getting dilute urine, what is your next step?
Administer DDAVP (synthetic ADH)
If you get a response with synthetic ADH, what is your diagnosis?
Central DI
If you do not get a response with synthetic ADH, what is your diagnosis?
Nephrogenic DI
Because the water deprivation test is no longer recommended by most internists anymore, what is an alternative to test water conservation of the renal tubules?
Vasopressin test
