Specimen requirement

Urine

CSF

Plain bottle

Minimum volume: 10 mL

Plain CSF bottle

Minimum volume: 2 mL

24 Hr urine:

U1 bottle

Authorisation code required

No

24 Hr available service

No

Method

Spectrophotometry

Reference interval

Urine: < 0.1 g/d

Urine total protein / creatinine ratio of > 3.5 mg/mg can be taken as nephrotic range proteinuria, and a range of < 0.2 is within normal limits.

(Source: NEJM 1983; 309: 1,543 - 6)

Normal urine total protein / creatinine ratio < 30 mg / mmol in pregnancy

(Source: ASSHP Consensus Statement 7 May 2000)

CSF: Adult: 0.15 - 0.45 g/L

(Source: from manufacturer's kit insert)

Clinical indication

Urine:

Assessment of renal diseases

CSF:

Assessment of CNS diseases

Result interpretation

Urine:

Protein loss in the urine is most commonly due to renal glomerular disease, especially if > 2 g / 24 Hr. Proteinuria of > 3 g / 24 Hr is required to establish the diagnosis of the nephrotic syndrome. In renal tubular disease, light chain proteinuria, orthostatic proteinuria and myoglobinuria, protein loss is usually < 1 g / 24 Hr.

CSF:

High protein levels are found in conditions where CSF circulation is impeded (e.g. spinal tumour); with meningeal inflammation (e.g. purulent or tuberculous meningitis); with increased vascular (blood-brain) permeability (e.g. encephalitis, Guillain-Barré syndrome); with local immunoglobulin production (e.g. multiple sclerosis); and whenever there is pus or blood in the CSF.

Results on blood-stained CSF are unreliable. Plasma total protein is approximately 200 times that of CSF, thus even a ‘slight’ contamination will artifactually increase measured CSF total protein.

Measurement of uncertainty

See table.

Frequency of measurement

Daily