Measurement of Serum Immunoglobulins: A National Survey of Practice

Aim To survey how serum immunoglobulins (IgG, IgA, IgM) are measured and reported across public hospitals in Ireland. Methods We developed a seven-point questionnaire to elicit the methodology, reporting and reference intervals of serum immunoglobulins. It was distributed electronically by email to sixteen laboratory managers of Irish public hospitals. Results A total of twelve questionnaires were completed. The test method was the same in each laboratory, whilst the analyser and source of the reference intervals varied. In some institutions, the reference interval differed within the adult age population and for sex. The IgG parameter contained the highest spread of results. The lower reference limit ranged 5.4-8.0 g/L, with a standard deviation of 0.81, and the upper reference limit ranged 14.9-18.2 g/L (SD 1.04). Conclusion Considerable variation exists in the reference intervals of serum immunoglobulins within different Irish public hospitals. This has important implications for users of the test, patients and referral patterns.