Do low total IgM antibody levels affect our ability to fight infections?

For years, I had Selective IgM Deficiency, since my total IgM antibodies were below the reference range.

Recently, I was surprised to see that my total IgM antibodies were now within the reference range, even though my total IgM antibody levels had not changed.

It turns out that the laboratory had expanded the reference range.
Usually they give you a hint under the result. Cool lab!