Screening for diabetic nephropathy: take your blinkers off

Abstract

Proteinuria is one of several markers of kidney damage in diabetes. The excretion of specific types of protein, such as albumin or low molecular weight globulins, depends on the type of kidney disease that is present.¹ One of the earliest changes in diabetes is an increase in glomerular filtration rate (GFR), or hyperfiltration, which is observed in patients with type 1 as well as many with type 2 diabetes and is accompanied by an increase in renal size.² The next observable change is the development of albuminuria, and current UK guidance recommends annual screening with the albumin creatinine ratio (ACR) to identify early kidney disease in patients with diabetes.³ Patients with diabetes with persistent microalbuminuria are at greatly increased risk for development of proteinuria (albuminuria >300 mg/day). However, it is important to exclude other causes of proteinuria in patients with diabetes, especially if there is no associated retinopathy. We report a case of an 81-year-old man with type 2 diabetes mellitus who presented with lower back pain and proteinuria but who had had normal/minimal microalbuminuria on his annual screening. He was diagnosed with multiple myeloma. The case highlights the importance of proteinuria in diagnosing multiple myeloma and the distinction between proteinuria in diabetic nephropathy and in multiple myeloma.