Improvement of hemoglobin levels after a switch from intravenous to subcutaneous administration of immunoglobulin in chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy

Abstract

Background: Intravenous immunoglobulin (IVIG) is recommended treatment for chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN). Recent studies have demonstrated that subcutaneous immunoglobulin (SCIG) is feasible, safe, and effective in both disorders. IVIG leads to transient hemolysis and, consequently, we hypothesized that frequent small doses of SCIG exerts less hemolytic activity than a few larger doses of IVIG.

Study design and methods: In an open-label study, 23 three patients treated with IVIG for CIDP or MMN were switched to SCIG at an equal dosage. IVIG was administered two to three times for 6 weeks. Two weeks after the last IVIG infusion at Week 8, SCIG was initiated with injections twice or thrice weekly until Week 20. Blood samples were drawn 2 weeks after IVIG at Weeks 2 and 8 and during SCIG at Weeks 14 and 20 determining hemoglobin (Hb) and hemolytic variables.

Results: Seventeen patients completed the study. At enrollment, the Hb level was 138 ± 12 g/L, haptoglobin level was 1.4 ± 0.5 g/L, reticulocyte count was 58.7 × 10⁹ ± 21.3 × 10⁹ /L, and bilirubin level was 6.6 ± 2.3 µmol/L. The average of the two blood samples drawn at comparable intervals during IVIG and SCIG showed that Hb increased from 135 ± 15 to 138 ± 15 g/L (p = 0.03). During IVIG the hemolytic variables showed signs of mild hemolysis that improved during SCIG, haptoglobin increasing from 1.2 ± 0.5 to 1.5 ± 0.6 g/L (p = 0.002), reticulocytes decreasing from 71.9 × 10⁹ ± 35.8 × 10⁹ to 54.5 × 10⁹ ± 16.3 × 10⁹ /L (p = 0.02), and bilirubin decreasing from 7.3 ± 2.8 to 5.8 ± 1.8 µmol/L (p = 0.001).

Conclusion: A switch from IVIG to SCIG was associated with a slight increase of Hb levels and an improvement of laboratory variables related to hemolytic activity.