Not all abnormal results on SPEP/IFE and sFLC indicate multiple myeloma. M protein and/or abnormal free light chain ratios may also be present in cases of premalignant plasma cell disorders such as MGUS, immune suppression or autoimmunity, renal impairment, infection, and other plasma cell disorders.6,9 Test results must be interpreted in context with the patient’s signs and symptoms.
Referrals to hematology/oncology should be informed by the patient's current medical conditions, along with concerning findings from their laboratory tests, suggestive of the possibility of multiple myeloma.
Urgent referrals are appropriate for patients with an identified IgD or IgE paraprotein, as well as for patients with significantly abnormal M protein concentrations or sFLC ratios.14
Any detection of M protein or free light chain ratio imbalance merits consultation with a hematology/oncology specialist.2 Patients with slight abnormalities or borderline results may require follow-up testing or ongoing monitoring; discussion with a specialist can inform the best course of action.14
The decision to act upon SPEP, IFE, or sFLC is case dependent. Lab results should always be evaluated in the context of clinical symptoms of an individual patient. The considerations above are not a substitute for hematologist consultation.