Paraprotein-induced spurious hypercalcaemia: diagnostic pitfalls in two cases.

Area of Science:

• Clinical Biochemistry
• Immunology

Background:

• Paraproteins are abnormal proteins that can interfere with laboratory assays.
• Spurious laboratory results can lead to misdiagnosis and inappropriate patient management.

Purpose of the Study:

• To report two cases where paraprotein caused falsely elevated serum calcium and Vitamin D measurements.
• To highlight the importance of recognizing assay interference in patients with paraproteinemia.

Main Methods:

• Review of clinical biochemistry results from two patients with paraprotein.
• Comparison of standard laboratory measurements with alternative assay methods for calcium and Vitamin D.
• Identification of assay interference due to paraprotein.

Main Results:

• Standard assays indicated hypercalcemia and elevated serum Vitamin D in both patients.
• Alternative measurement methods revealed that the elevated results were spurious.
• The presence of paraprotein was identified as the cause of the interference.

Conclusions:

• Clinicians must consider the potential for assay interference in patients with paraproteins or other protein abnormalities.
• Awareness of spurious results can prevent unnecessary investigations and treatments, safeguarding patient health and resources.