Myeloma IgD κ merupakan kasus keganasan sel plasma yang jarang dijumpai, dan belum pernah dilaporkan di Indonesia. Pada keadaan normal, kadar IgD dalam darah sangat rendah, sehingga peningkatan kadar IgD dalam darah dapat terlewatkan pada pemeriksaan elektroforesis protein serum. Pada makalah ini dilaporkan kasus seorang wanita 59 tahun dengan nyeri tulang hebat. Pemeriksaan radiologi menunjukkan adanya fraktur kompresi torakal dan penyempitan foramen torakal. Diagnosis mieloma pada pasien ini ditegakkan berdasarkan kriteria WHO, stadium berdasarkan kriteria Durie Salmon, dan prognosis buruk berdasarkan International Prognostic Index dari International Myeloma Working Group. Pada elektroforesis protein serum dijumpai spike monoklonal yang kecil dan pada imunofi ksasi didapatkan IgD κ and free light chain κ.

The light chains of immunoglobulin are produced in larger quantity rather than heavy chains, therefore small amount of free lightchains (FLC) can be found in the blood of healthy individuals. Free light chain production is increased in the clone’s proliferation ofmalignant B cells, i.e. in myeloma. Therefore the FLC level measurement can be used for diagnosis aid of myeloma and related B cellsdisorders. The aim of this study is to establish reference range of serum FLC κ, FLC λ, and κ/λ ratio in population ≥40 year’s old usingimmunoturbidimetry assay. Serum FLC κ, FLC λ and κ/λ ratio were measured in 240 healthy male and female attending medical checkup in MMC hospital. Healthy subjects were determined by anamnesis and physical examination, with routine haematology, ESR, andserum creatinine level within normal ranges. The serum FLC assays were performed in the Clinical Pathology Laboratory, RSCM, usingHitachi 912 with immunoturbidimetry method. The results were analyzed by SPSS 11.5 program. Serum FLC normal reference valuein 40-84 years old healthy subjects are: FLC κ 11.7–30.6 mg/L, FLC λ 9.7–25.0 mg/L, and κ/λ ratio 0.79–1.75. This research is thefirst study for finding serum FLC values in the Indonesian population. The normal reference value found is similar with another studyusing the same platform analyzer.