Acute Kidney Injury

Question 1

What is acute kidney injury?

Answer 1

Abrupt decline in renal function leading to increase nitrogenous waste products normally excreted by the kidney

Question 2

What are the CFx of AKI?

Answer 2

• Azotemia (increased BUN, Cr)

- Abnormal urine volume (anuria, oliguria, polyuria)

Question 3

What are the most common causes of AKI in hospitalised patients?

Answer 3

• Prerenal azotemia

- ATN

Question 4

Features suggesting pre-renal aetiology of AKI?

Answer 4

• Clinical: dec BP, inc HR, orthostatis hTN and BP changes
• Increased [urea]&raquo_space; [Cr]
• Urine osmolality >500mOsm/kg
• Na+ excretion

Question 5

Features suggesting renal aetiology of AKI?

Answer 5

• Appropriate clinical contest

- Urinalysis +ve for casts

Question 6

Features suggestive of post renal aetiology?

Answer 6

• Known solitary kidney
• Older man
• Recent peritoneal surgery
• Anuria
• Palpable bladder
• U/S: hydronephrosis

Question 7

Which drugs are involved in pre-renal azotemia?

Answer 7

• Anti-hypertensives
• Diuretics
• NSAIDs
• ACEi/ARBs

Question 8

Ix in AKI?

Answer 8

• Blood: FBE, UEC, CMP
• Urine: volume, MCS, urinalysis
• Foley catheter: r/o obstruction
• Fluid challenge (r/o most prerenal causes)
• Imaging: Renal Tract U/S

Question 9

What are the indications for biopsy in AKI work up?

Answer 9

• Diagnosis not certain
• Prerenal azotemia or ATN unlikely
• Oliguria persists >4wk

Question 10

Preliminary management of AKI?

Answer 10

PRE-RENAL:
-correct pre renal factors: optimise volume status and CV performance -> fluids that will stay in plasma (NS/alb/blood)
-hold ACEi/ARB
RENAL:
-address reversible renal causes: withhold nephrotoxins, treat infection, optimise electrolytes
POST RENAL:
-consider obstruction: structural (stones, strictures) vs functional (neuropathy)
-Rx: Foley / indwelling bladder catheter / stenting

Question 11

How is fluid overload managed in AKI?

Answer 11

• NaCl restriction

- High dose loop diuretics

Question 12

Management of complications in AKI?

Answer 12

• Manage fluid overload
• Correct hyperkalemia
• Renal dosing of meds
• Dialysis

Question 13

What are the types of complications of renal failure presentation?

Answer 13

• Volume overload
• Electrolyte abnormalities
• Uremic syndrome

Question 14

Why does volume overload occur in renal failure?

Answer 14

Due to increase in total body Na+ content

Question 15

What are the signs of renal failure volume overload?

Answer 15

• Weight gain
• HTN
• Pulmonary / peripheral oedema

Question 16

Pattern of electrolyte abnormalities in renal failure?

Answer 16

HIGH: K+, PO4^3-, Ca2+ (rare), uric acid
LOW: Na+, Ca2+, HCO3-

Question 17

In what setting would Ca2+ be elevated in renal failure?

Answer 17

• Recovery phase after rhabdomyolysis induced AKI

- Hypercalcemia contributes to renal failure: sarcoidosis, MM

Question 18

What are the complications of AKI?

Answer 18

• CNS: dec LOC, stupor, seizure
• CVS: cardiomyopathy, CHF, arrhythmia, pericarditis, atherosclerosis
• GI: PUD, gastroduodenitis, AVM
• HAEM: anemia, bleeding tendency, infections
• ENDO: decreased testosterone, estrogen, progesterone; increased: FHS, LH
• METABOLIC: renal osteodystrophy, hypertriglyceridemia, insulin resistance
• DERM: pruritus, ecchymosis, haematoma, calciphylaxis

Question 19

What is renal osteodystrophy?

Answer 19

Secondary increased PTH due to decreased Ca2+, high PO4(3-) and low active Vit D.