Paediatrics: Acute kidney injury

Acute kidney injury

Acute kidney injury (AKI) is a sudden reduction in glomerular filtration rate resulting in an increase in blood concentration of urea and creatinine and disturbed fluid and electrolyte homeostasis.

Classification

The causes of AKI can be divided into pre-renal, renal, and post-renal. A patient may have more than one cause for their AKI.

History

It is important to include the following points:

•   History of sore throat/rash (e.g. streptococcal glomerulonephritis).

•   Urinary symptoms of:

o haematuria, frequency, dysuria (e.g. pyelonephritis);

o poor stream (e.g. PUV).

•   Significant antenatal history.

Drugs.

Examination

It is important to assess and document the following.

• Height and weight (compare with any recent/past measurements).

• Fever.

• Hydration status: any evidence of oedema/dehydration?

• Haemodynamic status including BP.

• Presence of any rashes/arthropathy.

• Abdomen: tenderness or masses.

• Neurology: exclude possible neuropathic bladder.

Investigations

Urine

• Urinalysis with microscopy of fresh urine, e.g. evidence of casts.

• Culture, e.g. pyelonephritis.

• Osmolality, Na, creatinine, fractional excretion of sodium.

• Protein:creatinine ratio to document proteinuria if dipstick +ve.

• Myoglobin if evidence of rhabdomyolysis.

·Urine calcium/oxalate to creatinine ratios if renal calculi suspected.

Blood investigations

• Urea, electrolytes, creatinine, Ca²⁺, PO₄^3–, albumin, glucose, bicarbonate.

• Plasma osmolality.

• FBC and film.

• Blood cultures, if clinically septic.

• In suspected nephritis:

o complement levels;

o anti-streptolysin O titre (ASOT), antiDNAaseB;

o antinuclear antigen (ANA), anti-dsDNA, anti-neutrophil cytoplasmic antibodies (ANCA).

• Uric acid if tumour lysis suspected.

• Creatinine kinase if possible myoglobinuria.

• Clotting if septic or potential need for biopsy or dialysis access

• Drug levels if relevant (e.g. gentamicin).

• Escherichia coli 0157 serology.

Cultures

• Stool culture: E. coli 0157 (HUS).

• Throat swab.

Radiology

• US(+/– Doppler): kidneys and bladder.

CXR if evidence of fluid overload.