OBJECTIVE:

To analyze the relationship between the monoclonal bands detected in serum protein electrophoresis and renal involvement.

MATERIALS AND METHODS:

An observational, descriptive, and retrospective study was conducted based on the results of electrophoresis and immunofixation carried out at the Laboratorio de Diagnóstico Clínico del Centro de Investigaciones Médico Quirúrgicas in Havana, Cuba, within the time frame of January 2010 and December 2016. Inclusion criteria: patients with monoclonal component detected in electrophoresis and confirmed through immunofixation and patients with no monoclonal component in protein electrophoresis but detected in immunofixation performed for diagnostic suspicion of multiple myeloma. The protein electrophoresis tests in serum and 24-hour urine were conducted in agarose gel, utilizing the automated Hydrasys 2 system (Sebia®). The Kolmogorov-Smirnov test, chi-square test, and Student’s t test were employed for the statistical analysis and the 95% CI (α = 0.05) was considered statistically significant.

RESULTS:

73 patients with monoclonal gammopathy were registered. Immunoglobulin values were within the reference limits in 17 patients. The majority of patients had elevated serum creatinine levels (129 ± 46 μmol/L), but only 7/73 had the diagnosis of kidney failure associated with the monoclonal component. Immunoglobulin concentration (IgG, IgA, and IgM), according to their reference values, was related to the type of monoclonal component detected. There was one case of IgD myeloma, with the onset of kidney failure, and normal serum protein electrophoresis.

CONCLUSIONS:

Immunofixation continues to be a useful laboratory method for diagnosing monoclonal gammopathy, especially when protein electrophoresis does not suggest that alteration and kidney function can consequently be affected.

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