diagnosis of proteinuria in primary care
Last reviewed 11/2021
- dipstick urinanalysis - highly specific in detecting glomerular proteinuria - albuminuria - in excess of 300 mg/d
- dipstick urinanalysis will not detect microalbuminuria in early diabetic nephropathy (30-300mg/d); also will not detect Bence Jones protein
- if proteinuria is detected then it must be determined whether
- the proteinuria is persistent?
- the amount of protein excretion
- a 24-hour urine collection is indicated may be indicated if there is persistent proteinuria, protein detected on at least two urine samples (see notes)
- urine microscopy - will help identify proteinuria, microscopic haematuria and proteinuria is suggestive of glomerular disease
Notes (2):
- no need to perform 24 h urine collections for the quantitation of proteinuria in primary care
- positive dipstick test (1+ or greater) should result in a urine sample (preferably early morning) being sent to the laboratory for confirmation by measurement of the total protein:creatinine ratio or albumin:creatinine ratio (depending on local practice). Simultaneously, a midstream sample should be sent for culture to exclude urinary tract infection (UTI)
- urine protein:creatinine ratios >45 mg/mmol or albumin:creatinine ratios of >30 mg/mmol should be considered as positive tests for proteinuria.
- positive tests for proteinuria should be followed by tests to exclude postural proteinuria, by analysis of an early morning urine sample, unless this has already been done
- if a patient has two or more positive tests for proteinuria, preferably spaced by 1 to 2 weeks, the s/he should be diagnosed as having persistent proteinuria
Reference:
- Update 1998; 57 (4): 255-61.
- The Renal Association (May 2006).UK CKD Guidelines