Although most of the testing performed and the methodologies utilized in a clinical laboratory which serves a pediatric institution are very similar to those found in adult laboratories, a few differences stand out. Differences include devising ways to deal with small test volumes and different test menus than those found in laboratories that serve adult patients. One such test menu differences is the lack of serum protein electrophoresis (SPEP) testing in pediatric labs.
SPEP’s are essentially performed for the main purpose of helping to diagnose and then monitor the treatment of multiple myeloma. SPEPs provide this help by detecting, identifying by reflex immunofixation electrophoresis (IFE), and quantifying monoclonal gammopathies. Children don’t get multiple myeloma. After 20 years of signing out SPEP results at the county hospital next door, the youngest person with a diagnosis of multiple myeloma that I’ve seen was 24 years old. Thus in general SPEP’s are not ordered on children, nor performed in pediatric labs.
Recently however, I learned that although children don’t get multiple myeloma, they do in fact get monoclonal gammopathies. An SPEP ordered on a 7 month old patient in my institution came back with a very clear biclonal gammopathy, identified by IFE as an IgG kappa and an IgA kappa. This child has no bone marrow indication of abnormality, although she does have a deficiency of B-cells along with plasma cell infiltrates in the liver and duodenum.
A little searching determined that apparently, monoclonal spikes on SPEP’s in children are not at all unusual. A study published in 2014 (1) looked at 695 children who had SPEPs performed, and 11% of those children had a monoclonal gammopathy, although none of them had multiple myeloma. The most common associated diagnosis was ataxia-telangiectasia (22%), with a wide range of other diagnoses being found in these children, including some immunodeficiencies, autoimmune diseases, various hematological disorders and a few solid organ malignancies.
Thus it appears that monoclonal gammopathies are present in children and have an entirely different meaning than they do in adults. In addition, currently monoclonal gammopathies in children have no clear diagnostic utility. Perhaps that is the real reason we don’t routinely perform them in the pediatric population.
- Karafin MS, Humphrey RL, Detrick B. Evaluation of monoclonal and oligoclonal gammopathies in a pediatric population in a major urban center. AJCP 141:482-487. 2014
-Patti Jones PhD, DABCC, FACB, is the Clinical Director of the Chemistry and Metabolic Disease Laboratories at Children’s Medical Center in Dallas, TX and a Professor of Pathology at University of Texas Southwestern Medical Center in Dallas.