Resolution of dysglycaemia after treatment of monoclonal gammopathy of endocrine significance

Abstract

In very rare cases of monoclonal gammopathy, insulin-binding paraprotein can cause disabling hypoglycaemia. We report a 67-year-old man re-evaluated for hyperinsulinaemic hypoglycaemia that persisted despite distal pancreatectomy. He had no medical history of diabetes mellitus or autoimmune disease but was being monitored for an IgG kappa monoclonal gammopathy of undetermined significance. On glucose tolerance testing, hyperglycaemia occurred at 60 minutes (glucose 216mg/dL), and hypoglycaemia at 300 minutes (52mg/dL) concurrent with an apparent plasma insulin concentration of 52,850pmol/L on immunoassay. Laboratory investigation revealed an IgG2 kappa with very high binding capacity but low affinity (Kd 1.43x10-6 mol/L) for insulin. The monoclonal gammopathy was restaged as smouldering myeloma not warranting plasma cell directed therapy from a haematological standpoint. Plasma exchange reduced paraprotein levels and improved fasting capillary glucose concentrations. Lenalidomide was used to treat disabling hypoglycaemia, successfully depleting paraprotein and leading to resolution of symptoms.

Monoclonal Gammopathy of Undetermined Cardiovascular Significance; Current Evidence and Novel Insights

“…Landgren et al also examined the association between DM and MGUS and found no significant association [21]. Interestingly, a recently published case report described a case of hypoglycemia due to insulin-binding paraprotein that resolved following treatment with lenalidomide to deplete the plasma cell clone [22].…”