Acute Renal Failure

Question 1

acute renal failure (ARF) - define

Answer 1

clinical syndrome characterised by the sudden onset of haemodynamic, filtration and excretory failure of the kidneys, subsequent accumulation of metabolic (uraemic) toxins and dysregulation of fluid, electrolyte and acid-base balance.

Question 2

CKD vs ARF

Answer 2

ARF potentially reversible if diagnosed early
renal ultrasound + PE differs (CKD in worse body condition)
chronic weight loss + PU/PD vs toxins

Question 3

oliguria - define

Answer 3

low output of urine

Question 4

anuria - define

Answer 4

no output of urine

Question 5

Clinical presentation – History

Answer 5

often non-specific
malaise, lethargy, weakness, anorexia, vomiting, diarrhoea
known toxin ingestion
altered urine output
signs of concurrent disease

Question 6

Clinical presentation – PE

Answer 6

dehydration
oral ulceration/uremic odour
hypothermia
bradycardia/tachycardia
swollen, painful kidneys – or normal
signs of concurrent disease

Question 7

causes of azotemia

Answer 7

High production nitrogenous waste substances (pre-renal)
Low GFR (dehydration/shock)
Reduced renal perfusion (pre-renal)
Intrinsic or functional renal disease (renal)
Urinary obstruction (post-renal)
Reabsorption urine escaped from urinary tract (post-renal)

Question 8

pre-renal vs renal - SG

Answer 8

pre-renal - >1.035 cat, >1.030 dog

renal - <1.030 dog normally betwen 1.007-25

Question 9

pre-renal vs renal - urine sodium conc

Answer 9

pre-renal - 20 mmol/l

Question 10

pre-renal vs renal - urine sediment

Answer 10

pre-renal - unremarkable

renal - infl + casts

Question 11

pre-renal vs renal - dipstick findings

Answer 11

pre-renal - none

renal - glucosuria (sometimes)

Question 12

pre-renal vs renal - response to fluids

Answer 12

pre-renal - dramatic

renal - minimal

Question 13

pre-renal vs renal - hypovolaemia/dehydration

Answer 13

pre-renal - dramatic

renal - minimal

Question 14

interstitial nephritis - pyelonephritis - causes

Answer 14

ascending infection most common
may be PU/PD, not always azotaemic
may be asymptomatic
consider breaches of UT defences
anatomical-ectopic ureters, perineal urethrostomy
medical-diabetes, renal disease, nephroliths, iatrogenic-catheters, steroid therapy

Question 15

interstitial nephritis - pyelonephritis - treatment

Answer 15

treat aggressively
culture urine, empiric antibiotic therapy initially
re-culture on treatment, continue for 4-6 weeks
re-culture 1-2 weeks post-treatment

Question 16

interstitial nephritis - pyelonephritis

Answer 16

infection of renal pelvis + medulla

Question 17

interstitial nephritis - pyelonephritis - clinical signs

Answer 17

systemic illness, fever, renal pain, nephromegaly
PU/PD if e.coli is infecting organism
clinical signs may be absent

Question 18

interstitial nephritis - pyelonephritis - diagnosis

Answer 18

presumptive based on cultures from LUT

imaging

Question 19

interstitial nephritis - leptospirosis

Answer 19

zoonotic

infection by an serovar of leptospira bacteria

Question 20

interstitial nephritis - leptospirosis - concurrent diseases

Answer 20

hepatic necrosis, icterus, vasculitis, thrombocytopaenia

Question 21

interstitial nephritis - leptospirosis - diagnosis

Answer 21

showing high antibody titre to a non-vaccinal serovar

Question 22

interstitial nephritis - leptospirosis - treatment

Answer 22

Penicillin G or amoxycillin (acute tx.)

Doxycycline to clear carrier status

Question 23

tubular necrosis - toxins - other

Answer 23

hypercalcaemia
raisins/grapes (dogs)
ethylene glycol
plants (especially lilies in cats)
myoglobin/haemoglobin, heavy metals, pesticides/herbicides, snake venom

Question 24

tubular necrosis - toxins - drugs

Answer 24

Antimicrobials
Chemotherapeutics
NSAIDs
ACE-inhibitors
IV Contrast agents

Question 25

tubular necrosis - ischaemia - causes

Answer 25

↓ Intravascular volume, hypotension
Vascular disease (thrombosis, vasculitis)
↓ Effective Intravascular volume
sepsis
Drugs (Cyclosporine, NSAiDs, ACE-inhibitors)

Question 26

aquired ARF - causes

Answer 26

advanced age
fever
dehydration
cardiac disease
pre-existing renal disease
anaesthesia/surgery
administration of potentially nephrotoxic drugs

Question 27

treatment

Answer 27

prevent continued toxin exposure/give antidotes for toxins
treat primary underlying disease
correct ECF deficits + dehydration
correct potassium + acid-base balances
incr urine output
control vomiting + nutritional requirements
renal replacement therapy

Question 28

increasing urine output

Answer 28

Does not equate with GFR
Easier to maintain patient
Diuretics - furosemide, mannitol
Vasoactive agents - dopamine, diltiazem

Question 29

interstitial nephritis - leptospirosis - clinical signs

Answer 29

fever, muscle pain, vomiting and diarrhea, loss of appetite, lethargy, depression, and blood in the urine.
jaundice - hepatitis - destruction of liver cells by the bacteria.
Blood clotting problems
rare cases, leptospirosis can also cause respiratory distress and acute pulmonary (lung) hemorrhage.