is increased further, then precipitates get dissolved, and when cooled back to
40 – 60 C, the proteins precipitate again.
Precautions
- Urine should be acidic and clear.
- Temperature should be noted carefully.
8.2.5.2 Bradshaw’s Test
Principle
Bence-Jones proteins get precipitated by HCl.
Procedure
Layer the urine carefully over conc. HCl in a test tube. If Bence-Jones proteins are
present in urine, these will be precipitated by the HCl and form afine or heavy ring at
the interface of urine and HCl. Albumin may give a false positive test with HCl. To
rule out the possibility of presence of albumin, dilute the urine with distilled water
and repeat the test. The precipitate confirms the presence of Bence-Jones proteins.
8.2.5.3 Osgood and Haskin’s Test
Principle
Bence-Jones proteins are precipitated in saturated sodium chloride (NaCl) solution at
acidic pH.
Procedure
Add 0.5 ml of 50% acetic acid to 1.5 ml of saturated NaCl solution. To this, add
2.5 ml of fresh urine sample. The formation of precipitate at room temperature
indicates the presence of Bence-Jones proteins.
Clinical Significance
The excretion of an abnormal protein amount in urine is a reliable marker of renal
disease. When proteinuria is confirmed, 24 h urine sample is collected for protein
analysis. This will indicate the degree of proteinuria. Depending on clinicalfinding,
proteinuria can be divided into four types, viz., overload proteinuria, glomerular
proteinuria, tubular proteinuria, and post renal proteinuria (Fig.8.1).
Overflow or Overload ProteinuriaExcessive production of proteinuria is due to
hemoglobin or myoglobin and Bence-Jones proteins loss into urine. These proteins
are not initially associated with glomerular or tubular disease but may cause renal
disease. Myoglobin causes acute tubular necrosis. Bence-Jones proteins appear in
urine in multiple myeloma.
Glomerular Proteinuria It is due to increased glomerular permeability. Glomeru-
lar disease often causes heavy proteinuria (excretion of proteins >3–4 g/day). Small
36 8 To Perform Qualitative Tests for Urinary Proteins