From interference to insight: pseudo-lipidemia led to the diagnosis of Waldenström macroglobulinemia.

Waldenström macroglobulinemia (WM) is a rare hematological disorder with an annual incidence of about 3 per million. Its clinical manifestations are diverse and non - specific, and approximately 30% of patients are asymptomatic, making early diagnosis challenging. This paper reports a 73-year-old female who was admitted to the hospital due to atrial fibrillation. During a physical examination several years before the hospitalization, an elevated CA19-9 was detected, but the cause remained unclear after multiple outpatient visits. During cardiac markers testing, an abnormal serum index (HIL) suggested a lipidemic sample, yet the sample appeared clear visually. A Sia water test showed positive result, and subsequent serum protein electrophoresis confirmed the presence of M protein, leading to the diagnosis of WM. During the treatment in the following 6 years, it was found that the levels of CA19-9 and IgM fluctuated in parallel. Abnormal lipid indices and albumin-globulin ratio can provide important clues for the diagnosis of WM, but they may be overlooked in clinical practice. When the total protein increases with normal or decreased albumin levels, a reflex test of serum protein electrophoresis can help with early diagnosis. This case shows that understanding and using interference information in laboratory tests can assist in the diagnosis of WM.