What initial investigations should I perform for a patient presenting with suspected glomerulonephritis?

For a patient presenting with suspected glomerulonephritis, initial investigations should focus on assessing kidney function and identifying key markers such as proteinuria and haematuria.

• Urine Tests:
  • Perform a urine albumin:creatinine ratio (ACR) for the initial detection of proteinuria ³. A confirmed ACR of 3 mg/mmol or more is considered clinically important ³.
  • Use reagent strips to test for haematuria, evaluating further for results of 1+ or higher ³.
  • If persistent haematuria is present alongside an ACR of 30 mg/mmol or more, a urinary tract infection (UTI) should be excluded ¹,².
• Blood Tests:
  • Measure serum creatinine to estimate the glomerular filtration rate (eGFR) ³. If an eGFR result of less than 60 ml/min/1.73 m2 is found in an adult not previously tested, repeat the test within 2 weeks to confirm ³.
  • In adults with acute illness, investigate for acute kidney injury by measuring serum creatinine if symptoms or signs of nephritis (such as oedema or haematuria) are present ⁴.
• Imaging:
  • Consider offering a renal ultrasound scan if there is visible or persistent invisible haematuria, or if the eGFR is less than 30 ml/min/1.73 m2 (GFR category G4 or G5) ³.