Interpreting and investigating proteinuriaBMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e2339 (Published 05 April 2012) Cite this as: BMJ 2012;344:e2339
- Oliver T Browne, medical student,
- Sunil Bhandari, consultant nephrologist
- 1Department of Renal Medicine, Hull and East Yorkshire Hospitals NHS Trust and Hull York Medical School, Kingston upon Hull HU3 2JZ, UK
- Correspondence to: S Bhandari
- Accepted 29 December 2011
A 46 year old woman who had been treated for an uncomplicated E coli urinary tract infection three weeks previously returns to check her urine, as advised by her GP, since her initial urine dipstick test showed traces of protein, blood, leucocytes, and nitrites. She is a lawyer with no important medical history or previous urinary infections. She has recently taken a non-steroidal anti-inflammatory drug (NSAID) for menstrual pain. She has had no recent urinary symptoms or episodes of visible haematuria. There is no family history of renal disease, hypertension, or diabetes, and she is not pregnant.
On physical examination, her blood pressure is 144/82 mm Hg, and there is no oedema. However, the urine dipstick test shows ++ result for protein but no blood (see box 1 for glossary of terms).
Box1: Glossary of terms
The presence of dipstick positive proteinuria in two or more consecutive urine samples over a one to two week period. A previous urinary tract infection may theoretically affect the test, from the presence of leucocytes or alkalinisation of the urine leading to a false positive result for proteinuria. If the evidence is weak, the test should be repeated about two weeks later to check for persistent proteinuria. Repeat tests are more reliable for detecting renal pathology as they reduce the likelihood of transient proteinuria from exercise, stress, or fever.
This is rare in people over 30 years old. Usually it is manifest only when a person stands erect for long periods and disappears on lying down. The diagnosis is made by collecting split urine specimens for comparison. The daytime specimen typically has an increased concentration of protein, whereas a night time specimen has a normal concentration.
Proteinuria and albuminuria
These are an abnormal presence of protein …