Association of routine hematological parameters with the development of monoclonal gammopathies: a case-control study of 134,740 patients : Resubmitted to annals of Hematology 26 March 2024.

The diagnosis of multiple myeloma requires detection of paraproteinemia and confirmation of monoclonal bone marrow infiltration, along with signs of end-organ damage. Despite the increasing prevalence, serum paraproteinemia is not routinely measured. We examined the relationship between alterations in routine hematological parameters and the development of paraproteinemia in a case-control study. Data was retrieved from a laboratory database in the capital region of Denmark between 01/01/2012 and 31/12/2022. Patients were included if they had a test for paraproteinemia (n = 134,740) and at least one prior hematological parameter (white blood cells, hemoglobin and platelet count) with a minimum follow-up of 1 year.Between 96,999 and 103,590 patients were included in each of the three hematological groups. We found white blood cell count and the presence of paraproteinemia followed an inverse J-shaped curve, with the highest presence below 3 × 10 9 /L and above > 9 × 10 9 /L. The adjusted OR below and above the nadir of 4 × 10 9 /L was 1.61 (95% CI 1.25; 2.08, p < 0.0001) and 1.03 (95% CI 1.03; 1.04, p < 0.0001). Hemoglobin levels were inversely associated the presence of paraproteinemia, with the highest association below 6 mmol/L with an OR of 1.30 (95% CI 1.28; 1.32, p < 0.0001) adjusted for age and gender. Platelet count followed a U-shaped curve with the highest association at < 100 × 10 9 /L. The adjusted OR below and above the nadir of 250 × 10 9 /L was 1.13 (95% CI 1.10; 1.17, p < 0.0001) and 1.10 (95% CI 1.08; 1.12, p < 0.0001) respectively. In conclusion, all three parameters showed significant association with later paraproteinemia.