Laboratory: Clinical Biochemistry
Test Name:
PROTEIN, TOTAL - (U)
Test Code: TPU
Clinical Information:
Urine protein testing is used in the evaluation of renal disease and to rule out significant proteinuria in the assessment of hypertensive disorders of pregnancy.
Urine protein consists of plasma-derived proteins that have been filtered by renal glomeruli and have not been retained. Elevated concentrations of urine protein (proteinuria) is present in primary renal disease caused by glomerular or tubular defects. It is also seen in patients with systemic disorders that affect renal function such as hypertension, diabetes mellitus, vascular disease, neoplasia and some infectious diseases.
CAUTION: Random urinary protein to creatinine ratio is overestimated in dilute urine specimens (creatinine < 3 mmol/L) by most assays. As dilute urine is a common occurrence in pregnancy, an elevated protein to creatinine ratio should be confirmed on a more concentrated urine specimen. First morning specimens are preferred, but random specimens are acceptable if first morning specimens are not available.
In the assessment of renal function, patients with two or more positive quantitative urine protein tests temporally spaced by 1 or 2 weeks should be diagnosed as having persistent proteinuria and undergo further evaluation and management for chronic kidney disease.
In the diagnosis of hypertensive disorders of pregnancy, significant proteinuria is defined as urine total protein ≥ 0.3 g/d in a complete 24 hour urine collection or a random protein to creatinine ratio ≥ 30 mg/mmol. Proteinuria testing does not need to be repeated once significant proteinuria of preeclampsia has been confirmed.
National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF KDOQI) 2002 Clinical Practice Guidelines for Chronic Kidney Disease.
SOGC Clinical Practice Guideline - Diagnosis, Evaluation, and Management of the Hypertensive Disorders of Pregnancy. J Obstet Gynaecol Can 2014, 36(5): 416-438
Preeclampsia Screening: Evidence Report and Systematic Review for the US Preventative Task Force. JAMA 2017, 317 (16): 1668-1683
Collection Devices:
Collect 24h urine without preservative. Refrigerate 24h and random urine specimens until analysis.
Similar lab approved leak-proof containers acceptable.
Specimen Required:
Urine: 3.0 mL

Stability 7 days refrigerated, 1 month frozen
Referral:
Requisition:
Reference Values:
< 0.14 g/d
(g/d   x  1000 = mg/d)

< 25 mg/mmol creatinine
Availability:
Weekdays
See Also:
More Information: