AKI

Question 1

what are the risk factors for AKI?

Answer 1

• Diabetes
• CKD
• IHD/CCF
• Elderly >75
• Sepsis
• Medications – ACEi, ARBs, NSAIDs, Antibiotics

Question 2

what are the 3 stages of AKI according to the KDIGO guidelines?

Answer 2

stage 1 = serum creatinine is 1.5-1.9 x the baseline and urine output is <0.5ml/kg/h for 6-12hrs

stage 2 = serum creatinine is 2-2.9 x baseline. urine output is <0.5ml/kg/hr for >12 hrs

stage 3 = serum creatinine is 3x baseline OR initiation of renal replacement therapy. urine output is <0.3 ml/kg/h >24 hours or anuria for >12 hours.

Question 3

what are the pre renal causes of AK?

Answer 3

hypovolemia

decreased cardiac output

decreased effective circulating volume e.g congestive heart failure and liver failure

impaired renal autoregulation e.g NSAIDs, ACE-1/ARB, cyclosporine

Question 4

what are the intrinsic causes of AKI?

Answer 4

• glomerular e.g acute glomerulonephritis
• tubules and interstitial e.g ischaemia, sepsis/infection, nephrotoxins
• vascular e.g vasculitis, malignant hypertension

Question 5

name some exogenous endotoxins

Answer 5

iodine contrast

aminoglycosides

cisplatin

amphoteicin B

Question 6

name some endogenous endotoxins

Answer 6

haemolysis, rhabdomyosis, myeloma, intratubular crystals

Question 7

what investigations are done into AKI?

Answer 7

• URINE DIPSTICK (look for abnormal protein and blood)
• Daily FBC, U&Es, LFTs, Bone profile, CRP – incl. serum bicarbonate (CK if rhabdomyolysis suspected)
• Urine PCR, Urine MC+S, USS KUB (to rule out obstruction)
• If blood and protein on urine dipstick – perform c-ANCA (PR3) + p-ANCA (MPO) too look for vasculitis, anti-GBM, ANA, C3, C4 to look for lupus nephritis, serum immunoglobulins and electrophoresis to look for
  myeloma
• In case of associated thrombocytopenia consider HUS/TTP/Disseminated Intravascular Coagulopathy, request haemolysis screen - blood film, LDH, bilirubin, reticulocytes, haptoglobin, and call Renal SpR urgently.

Question 8

what should be done if post streptococcal GN is suspected?

Answer 8

If suspected post-streptococcal GN – do Anti-Streptolysin O Titres

this test is used to help determine whether you have had a recent strep infection

Question 9

when should cryoglobulins be checked?

Answer 9

Check cryoglobulins (immunoglobulins that precipitate in the cold and dissolve when warmed) if

unexplained rash,
peripheral neuropathy, hypocomplementaemia (used to asses disease activity in IC mediated disease) ,
known hepatitis C,
history of
lymphoproliferative disorder, or +ve RhF.

Question 10

how is AKI managed?

Answer 10

• Discontinue nephrotoxic agents if possible
• Ensure volume status and perfusion pressure – If dehydrated give IV fluids, If overloaded give diuretics, aim for euvolaemia
• Be aware of third space losses (patient may look overloaded but JVP & BP may be low indicating intravascular depletion)
• Consider function haemodynamic monitoring with Central Venous Pressure (CVP) line/Arterial line
• Monitor urine output and daily bloods (catheterise if necessary)
• Avoid hyperglycaemia
• Check for changes in drug dosing (antibiotic doses etc adjusted to renal function)
• Treat underlying cause
• Refer to specialist for consideration of renal replacement therapy
• Consider ICU admission

Question 11

what are the indications for renal replacement therapy for AKI?

Answer 11

• Hyperkalaemia refractory to medical therapy
• Metabolic acidosis resistant to medical therapy
• Fluid overload resistant to diuretics (anuric)
• Uraemic pericarditis
• Uraemic encephalopathy – vomiting, confusion, drowsiness, reduced consciousness
• Intoxications – ethylene glycol, methanol, salicylates, lithium