Estimated glomerular filtration rate

Philly O’Riordan; Paul E Stevens; Edmund J Lamb

doi:10.1136/bmj.g264

Practice Rational Testing

Estimated glomerular filtration rate

BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g264 (Published 24 January 2014) Cite this as: BMJ 2014;348:g264

Philly O’Riordan, general practitioner1,
Paul E Stevens, consultant nephrologist and medical director2,
Edmund J Lamb, consultant clinical scientist3

¹City Road Medical Centre, London, UK
²Kent Kidney Care Centre, East Kent Hospitals University NHS Foundation Trust, Canterbury, UK
³Clinical Biochemistry, East Kent Hospitals University NHS Foundation Trust, Canterbury CT1 3NG, UK

Correspondence to: E Lamb elamb{at}nhs.net

What should you do when confronted with a patient with previously unrecognised moderate chronic kidney disease? This article gives helpful advice in this not uncommon scenario

Learning points

Confirm a finding of low estimated glomerular filtration rate (eGFR) with a repeat sample taken after avoidance of meat for at least 12 hours. Consider spurious causes of low eGFR such as high muscle mass. Take into account normal biological and analytical variability when interpreting eGFR results (and most other laboratory tests)
A low eGFR result should prompt a check for proteinuria by measuring urinary albumin to creatinine ratio
Stage 3 (moderate) chronic kidney disease, especially in the absence of proteinuria or haematuria, is typically stable and can be safely managed in primary care
In some instances, the cause for a patient’s chronic kidney disease may be uncertain, but this does not affect the management

A 75 year old white woman presented to the emergency department after a fall with a displaced Colles’ fracture requiring surgical management. She was euvolaemic, her blood pressure was 158/89 mm Hg, and her body mass index was 19. She consumed no alcohol, smoked 20 cigarettes a day, and was not taking regular medication. Preoperative blood tests showed a serum creatinine concentration of 140 μmol/L (reference interval 49-90 μmol/L) and estimated glomerular filtration rate (eGFR) 32 mL/min/1.73 m². Blood electrolytes, liver function tests, and glucose concentration were normal. One day postoperatively her creatinine level remained increased (125 μmol/L, eGFR 36 mL/min/1.73 m²). On discharge, the orthopaedic team asked her general practitioner to investigate her renal function further.

What are the next investigations?