Abstract Objectives The study aims to show that in the follow-up of light chain multiple myeloma (LCMM) patients using the electrophoresis tests as used in multiple myeloma (MM) patients with intact (heavy chain–associated) M protein, may cause unnecessary testing. Methods The laboratory information system was searched retrospectively between 1 January 2022 and 31 December 2022. LCMM patients were characterized with positive urine immunofixation electrophoresis (UIFE), negative or positive serum immunofixation electrophoresis (SIFE), and both without any heavy chain component. Results The randomly selected 10 patients were 5 males and 5 females, with a median follow-up time of 42 months (95 % CI 30–82 months). During the follow-up of the 10 patients, a total of 215 serum protein electrophoresis (SPE), 351 SIFE, and 306 UIFE tests were studied. Overall, 4 of the 215 SPE tests, 62 of 351 SIFE, and 142 of 306 UIFE tests were reported as positive. In 62 positive SIFE tests, 33 were evaluated to be due to Daratumumab drug interference. The other 29 positive SIFE tests were accompanied by concomitant positive UIFE tests. When scored according to the official scoring system (SUT), total SPE, SIFE, and UIFE tests performed in the follow-up of these 10 patients cost a total of 66,913 points. Negative SPE and negative or avoidable SIFE tests cost 38,764 of 66,913 points (58 %). Conclusions The high rate of negative SPE and negative or avoidable SIFE tests indicated that the use of these tests should be carefully considered by the clinician in the follow-up of LCMM patients. Clinical guidelines should include clear directions for follow-up of subtypes of MM, particularly for LCMM.
Aydın et al. (Tue,) studied this question.