Type II Cryoglobulinaemia causing Monoclonal Gammopathy of Renal Significance.

A 53 year old female with a background of hypertension, hypothyroidism and Raynaud's was admitted with an acute ischaemic stroke and referred to the renal team after a routine urine dip revealed microscopic haematuria and nephrotic-range proteinuria. Blood tests revealed renal impairment, a monoclonal IgM kappa paraprotein, low complement C4 concentration and a positive rheumatoid factor. Active cryoglobulinaemia was suspected and testing demonstrated type II cryoglobulins secondary to the monoclonal IgM kappa paraprotein. Bone marrow biopsy was normal. Renal biopsy revealed cryoglobulinaemia associated membranoproliferative glomerulonephritis. Treatment with steroids and rituximab improved renal function and proteinuria. This case fits within the evolving spectrum of disorders now termed Monoclonal Gammopathy of Renal Significance and highlights the value of biopsying and treating these patients early.