A 52-year-old woman comes to the clinic for follow-up of type 2 diabetes mellitus that was diagnosed 6 months ago after she was hospitalized for cellulitis of the right lower leg. The patient's diabetes is managed with insulin in addition to diet and exercise. Her only other medical condition is hypertension, for which she takes antihypertensive medication. The patient's mother had systemic lupus erythematosus and died at age 60. Serum creatinine is 1.7 mg/dL. Urine albumin/creatinine ratio is elevated at 190 mg/g and was also elevated 3 months ago. Which of the following additional findings would most strongly support a diagnosis of diabetic nephropathy in this patient?

Question

A 52-year-old woman comes to the clinic for follow-up of type 2 diabetes mellitus that was diagnosed 6 months ago after she was hospitalized for cellulitis of the right lower leg.  The patient's diabetes is managed with insulin in addition to diet and exercise.  Her only other medical condition is hypertension, for which she takes antihypertensive medication.  The patient's mother had systemic lupus erythematosus and died at age 60.  Serum creatinine is 1.7 mg/dL.  Urine albumin/creatinine ratio is elevated at 190 mg/g and was also elevated 3 months ago.  Which of the following additional findings would most strongly support a diagnosis of diabetic nephropathy in this patient?

Quizplus · Accepted Answer

Explanation: Diabetic nephropathy (DN) is exceedingly common in patients with both type 1 and type 2 diabetes mellitus and is characterized by persistent albuminuria (≥30 mg/g) and/or decreased glomerular filtration rate (GFR) (eg, elevated creatinine). DN is typically slowly progressive for years before clinical signs occur. The diagnosis is usually made clinically, with renal biopsy reserved for patients with an unclear presentation. In the absence of signs suggesting another etiology (eg, casts in the urine, rapid progression of renal dysfunction), the diagnosis can be presumed in patients who have persistent albuminuria and/or decreased GFR and either of the following: Prolonged history of diabetes: Type 1 diabetes is typically clinically obvious at onset; therefore, DN may be assumed those with a disease duration of ≥5 years. In contrast, type 2 diabetes is often asymptomatic, so patients may have this disorder for years before the diagnosis, making the duration of the disease difficult to calculate. Proliferative diabetic retinopathy (PDR): Both PDR (ie, retinal neovascularization) and DN are chronic microvascular complications of diabetes due to persistent hyperglycemia, so the presence of PDR correlates with diabetic kidney disease. Therefore, patients may be diagnosed with DN if there is concomitant PDR, regardless of the length of time since the diagnosis. (Choice A) Renal size discrepancy is seen in patients with unilateral chronic kidney disease (eg, renal artery stenosis, ureteral obstruction). With prolonged DN, both kidneys would likely be shrunken and atrophic. (Choice B) Left ventricular hypertrophy correlates with chronic, uncontrolled hypertension. Although uncontrolled hypertension may be seen in patients with chronic kidney disease, it is not specific for DN. (Choice C) Although microscopic hematuria may occur with DN, it is nonspecific and may be seen in a variety of diseases (eg, malignancy, nephritic syndromes). (Choice D) DN usually develops over a prolonged period (years). Rapidly progressive renal dysfunction suggests an alternate diagnosis (eg, lupus nephritis) and further workup. Renal biopsy may be indicated. Educational objective: Diabetic nephropathy (DN) is characterized by persistent albuminuria (≥30 mg/g) and/or decreased glomerular filtration rate. In the absence of signs suggestive of another etiology, the diagnosis can be presumed in patients with renal dysfunction and either a prolonged history of diabetes (≥5 years for type 1 diabetes) or proliferative diabetic retinopathy, which correlates with the presence of DN.

A 52-Year-Old Woman Comes to the Clinic for Follow-Up of Type