Immunoturbidimetry and Nephelometry: Protein Analysis

Analyzer for immunoturbidimetric and nephelometric measurement of specific proteins

Immunoturbidimetry and nephelometry are two related methods for measuring specific proteins, based on the antigen-antibody reaction and subsequent measurement of light scattering by the resulting immune complexes. Both methods are widely used to quantify plasma proteins: CRP, immunoglobulins, complement components, and specific transport and acute-phase proteins.

How the Methods Differ

Both methods detect the interaction of light with immune complexes, but they measure different optical signals.

Parameter	Immunoturbidimetry	Nephelometry
What is measured	Attenuation of transmitted light	Light scattered at an angle
Detection angle	0° (in line with the beam)	usually 90° or another angle
Equipment	Standard clinical chemistry analyzer	Dedicated nephelometer
Sensitivity	Lower	Higher at low concentrations
Integration	Easily added to the clinical chemistry workflow	Standalone instrument

Proteins Measured

Acute-phase proteins: CRP (including hs-CRP), haptoglobin, ceruloplasmin
Immunoglobulins: IgG, IgA, IgM, free light chains
Complement components: C3, C4
Transport proteins: transferrin, prealbumin
Specific markers: cystatin C, microalbumin, rheumatoid factor

Practical Considerations

To extend the measuring range, latex particle-enhanced reactions are used (latex-enhanced turbidimetry), which increases sensitivity at low concentrations. It is important to account for the prozone effect (antigen excess), in which the signal paradoxically decreases at very high analyte concentrations; modern analyzers monitor for this phenomenon automatically.

Frequently Asked Questions

Which is more sensitive, turbidimetry or nephelometry?

Nephelometry is generally more sensitive at low concentrations because it measures scattered light against a dark background. Turbidimetry is easier to integrate into routine clinical chemistry analyzers.

What is the prozone effect?

It is a falsely low result caused by antigen excess. Modern instruments detect it with an antigen excess check.

Why are latex particles used?

Latex enhancement increases the size of the immune complexes and the amount of light scattering, which extends the measuring range and increases the sensitivity of the method.

Choosing a Specific Protein Analyzer

KombiMED GmbH is an independent procurement and market access partner for laboratory equipment from Europe. We will help you select a nephelometer or a clinical chemistry analyzer with turbidimetry to suit your laboratory's needs, and we provide delivery, installation and commissioning, and staff training.

See also:

Analytical methods in clinical chemistry: an overview
UV-Vis spectrophotometers
Coagulometry and hemostasis testing
Contact KombiMED for help selecting equipment