Approach to Azotemia & Acute Kidney Injury SA Flashcards
1
Q
what are the functions of the kidneys (6)
A
- filtration of blood and excretion of metabolic waste
- acid-base balance
- water/volume regulation
- electrolyte & mineral homeostasis
- blood pressure regulation
- erythropoitin release
2
Q
what are the presentations of kidney disease (8)
A
- PUPD
- inappetance/weight loss
- depression
- GI signs: vomiting/nausea/diarrhea
- ascites/subcutaneous edema
- hematuria
- pain
- abdominal mass
3
Q
what is azotemia
A
abnormal increase in the concentration of non-protein nitrogenous wastes in blood
increased urea and creatinine
4
Q
what does azotemia suggest and what does it not equal
A
suggests failure of filtration and excretion of metabolic waste but doesn’t equal kidney disease
5
Q
what are serum urea levels affected by (8)
A
- species
- age
- liver function
- dietary protein content (including GI bleeding)
- endogenous protein catabolism
- hydration
- renal function
- LUT function
6
Q
what does serum creatinine decrease with
A
- reduced muscle mass
7
Q
what does serum creatinine increase with (2)
A
- reduced renal clearance
- urine excretion failure (ex. urinary tract rupture)
8
Q
what is glomerular filtration rate
A
flow rate of filtered fluid through the kidneys
defines the excretory function of the kidneys
9
Q
what reduces GFR (3)
A
- decreased renal perfusion
- decreased renal function (ex. fewer nephrons)
- obstruction of urine flow
10
Q
why is urea not ideal for assessing renal excretory function (GFR)
A
affected by many other factors (variable rate of synthesis)
although freely filtered it is reabsorbed in the tubules and collecting ducts at variable rate
11
Q
why is creatinine better at measuring GFR
A
produced at constat rate
freely filtered with no reabsorption
12
Q
what are the limitations of using creatinine as a measure of GFR (3)
A
- azotemia doesn’t develop until GFR has decreased to 25%
- relationship between creatinine & GFR is not linear and the change in serum creatinine must be considered in the light of the starting value
- doesn’t tell you why GFR has fallen
13
Q
what does creatinine not discriminate between (4)
A
- cause of azotemia (not specific)
- acute kidney or chronic kidney disease
- reversible or irreversible renal failure
- causes of renal failure
14
Q
what is SDMA
A
symmetric dimethylarginine
15
Q
where does SDMA come from and where is it excreted
A
from protein degradation
renally excreted
marker of GFR
16
Q
what are the clinical signs of azotemia
A
azotemia is a biochemical change
not all azotemic patients have clinical signs
severity of clinical signs not directly proportional to magnitude of increase
rate of accumulation has an effect on severity of signs
17
Q
what are the clinical signs of uremia (6)
A
constellation of adverse clinical effects that develops as a consequence of severe renal excretory failure
severity of signs depends on magnitude of excretory failure and rate of deterioration
- inappetance
- depression
- vomiting/nausea
- halitosis
- oral ulceration/stomatitis
- diarrhea
18
Q
are all uremic patients azotemic
A
yes
19
Q
are all azotemic patients uremic
A
no
20
Q
what are the causes of azotemia (3)
A
- pre renal: inadequate renal perfusion
- renal: intrinsic renal failure
- post renal: post-renal obstruction or rupture of urinary tract
21
Q
what are pre renal azotemia causes (3)
A
- hypovolemia
- hypotension
- aortic/renal thromboembolism
22
Q
what are renal causes of azotemia (2)
A
- nephron damage
- nephron loss
23
Q
what are post-renal causes of azotemia (3)
A
- ureterolith
- urethrolith
- bladder rupture
24
Q
how do you differentiate the causes of azotemia
A
- history
- clinical exam
- urinalysis
cannot use magnitude of azotemia to determine its cause
25
if the patient is not drinking and azotemic what type of azotemia is it likely
pre-renal
26
if the patient is experiencing increased losses and azotemic what type of azotemia is it likely
pre-renal
27
if the patient is dysuric and stranguria and is azotemic what type of azotemia is it likely
post-renal
28
what could be the reasons of failure to pass urine (2)
1. not producing urine (renal)
2. can't pass urine (post-renal)
29
if there is evidence of dehydration on clinical exam what would the cause of azotemia be
pre-renal +/- renal +/- post-renal
30
if there is a grossly enlarged bladder on clinical exam what would the cause of azotemia be
post-renal
31
if there is localized subcutaneous fluid around perineum or ventral abdomen on clinical exam what would the cause of azotemia be
post-renal
32
if there is free peritoneal fluid (urine) on clinical exam what would the cause of azotemia be
post-renal
33
if there is difficult/impossible to pass urinary catheter on clinical exam what would the cause of azotemia be
post-renal
34
if there is active sediment with tubular casts on urinalysis what type of azotemia
renal
35
if there is hematuria on urinalysis what type of azotemia
renal or post renal
36
if the USG is hypersthenuric what type of azotemia would this be
pre-renal
37
if the patient has been healthly until recently would the renal azotemia be acute or chronic
acute
38
if the patient has had months of PUPD would the renal azotemia be acute or chronic
chronic
39
would acute or chronic renal azotemia patient have a history of occasional vomiting
chronic
40
if the patient is experiencing anuria/oliguria and maybe polyuric is this a acute or chronic renal azotemia
acute
41
if the patient has a history of weight loss is it likely acute or chronic renal azotemia
chronic
42
on clinical exam what would the size of the kidneys be in acute renal azotemia
kidneys normal sized or large
may be painful
43
on clinical exam what would the size of the kidneys be in chronic renal azotemia
kidneys usually small and non-painful
44
what is the appearance of mucus membranes in acute renal azotemia
pink
45
what is the appearance of mucus membranes in chronic renal azotemia
may be pale
46
what would the coat condition in acute renal azotemia
good coat condition
47
what would the coat condition in chronic renal azotemia
poor coat
48
what would the body condition score of acute renal azotemia
normal body condition score
49
what would the body condition score of chronic renal azotemia
poor body condition score
50
would anemia be present in acute renal azotemia
not usually present
51
would there be anemia in chronic renal azotemia
non-regenerative anemia usually
52
what would the urine sediment be with acute renal azotemia
often contains cells, casts, debris
53
what would the urine sediment be in chronic renal azotemia
usually negative
54
would there be hyperkalemia in acute or chronic renal azotemia
in acute
55
would there be metabolic acidosis in acute or chronic renal azotemia
acute
56
what is the definition of renal disease
damage or functional impairement of kidneys
varying severity
57
what is the definition of renal insufficiency
functional impairment not severe enough to cause azotemia, but sufficient to cause loss of renal reserve
58
what is the definition of renal failure
functional imparment severe enough to cause azotemia
urine concnetrating ability usually impaired
59
what is the definition of acute kidney injury
sudden, often reversible reduction of the elimination and metabolic functions of the kidneys
60
what is the risk to the kidneys in acute kidney injury (4)
1. huge blood flow
2. roxins may be secreted/reabsorbed by tubular cells
3. potential concentrating effects of toxins in urine
4. play a role in biotransformation of drugs/toxins
61
what are reduced renal perfusion causes of reduced renal perfusion (5)
1. dehydration
2. hypovolemia
3. decreased cardiac output
4. hypotension
5. shock
62
what are infectious causes of acute kidney disease (2)
1. leptospirosis
2. borreliosis (lyme disease)
63
what are nephrotoxic drugs that can cause acute kidney disease (4)
1. NSAIDs
2. aminoglycosides
3. doxorubicin (cats)
4. cisplatin
64
what are toxins that can cause acute kidney injury (3)
1. lilies (cats)
2. grapes/raisins (dogs)
3. ethylene glycol
65
what is the intiiation phase of acute kidney injury
something damages part of some of the nephrons leading to dysfunction
66
what is the extension phase of acute kidney injury
ischemia, hypoxia, inflammation and cellular injury result in cell death and further nephron damage
clinical and laboratory abnormalities develop
67
what is the recovery phase of acute kidney injury
gradually reversible renal lesions are repaired and viable nephrons hypertrophy
68
what would the early presenting signs of acute kidney injury be
acute onset of signs of uremia
inappetance, depression, vomiting/nausea, halitosis, diarrhea
69
what should you pay particular attention to during the clinical exam of a suspected acute kidney injury patient (4)
1. hydraiton & volume status: often dehydrated
2. oral examination: may have uremic ulcers, halitosis
3. renal palpation: usually normal to large, may be painful
4. bladder size and shape: urine production
70
how would you diagnose acute kidney injury (4)
1. identify azotemia
2. reule out post-renal causes (history & clinical exam)
3. identify reduced urine concentrating ability (urinalysis)
4. differentiate acute from chronic kidney disease (history, clinical exam, lab findings, affects treatment and short and long term prognosis)
71
what would the potassium values be in acute kidney injury
initially hyperkalemic
72
what would the phosphate values be in acute kidney injury
initially normal, become hyperphosphatemic
73
what would the calcium values be in acute kidney injury
may be high, low or normal
if markedly increased consider hypercalcemia as cause
74
what would the PCV & TP values be in acute kidney injury
may be increased due to dehydration
75
what can acute kidney injury appear as
hypoadrenocorticism (Addison's disease)
often patients will have
azotemia (pre-renal)
hyperkalemia
minimally concentrated urine
76
what additional observations are important during the clinical exam of acute kidney injury (5)
1. urine output
2. ocular exam (evidence of hypertensive retinopathy)
3. blood pressure measurement
4. rectal exam (neoplasia)
5. peripheral lymph node palpation (neoplasia)
77
what is oliguria
\<0.25 ml/kg/hr
78
what is polyuria
\>2ml/kg/hr
79
what is normal urine output
1-2ml/kg/hr
80
what should you assess on renal ultrasound (4) when diagnosing acute renal injury
1. renal size
2. renal architecture
3. size of renal pelvis
4. renal blood flow
81
what should you assess on abdominal radiography when diagnosing acute kidney injury (3)
1. renal size
2. renal mineralization
3. ureteroliths
82
what are the general principles of treating acute kidney injury (6)
1. remove inciting cause
2. restore renal perfusion
3. monitor urine output & consider drugs to increase urine output (only if necessary)
4. monitor electrolytes, acid-base balance, hydration status q6-8h or more and treat as necessary
5. treat uremic complications and provide nutrition
6. investigate underlying causes
83
what fluid therapy would be used for acute renal injury
replace fluid deficits quickly (4-6hr)
0.9% saline usually
84
what is the purpose of treating acute renal injruy with fluids
to try and remove pre-renal component
protect against further ischemic damage
85
how do you increase urine output if patient is anuric
try mild volume expansion if no signs of overhydration (3-5% of patient's body weight)
consider diuretic administration (frusemide or mannitol) --\> don't use until dehydration is corrected
86
what is the mortality rate of kidney injury for cats and dogs
dogs 53%
cats 45%
depends on the cause
87
what are potential risk factors of kidney disease (9)
1. pre-existing renal disease
2. dehydration
3. sepsis
4. hypotension
5. decreased cardiac output
6. trauma
7. advanced age
8. hypoalbuminemia
9. use of potentially nephrotoxic drugs
