Approach to Proteinuria in Adults and Elderly

Fatemeh Akbarian, MD, Research Fellow, University of Toronto, Toronto, ON.
Hatim Al Lawati, MD, FRCPC, Cardiology Resident, Division of Cardiology, Faculty of Medicine, University of Toronto, Toronto, ON.
Mohammad Ali Shafiee, MD, FRCPC, General Internist, Nephrologist, Department of Medicine, Toronto General Hospital, University Health Network; Clinician Teacher, University of Toronto, Toronto, ON.

Abstract
Proteinuria can create one of the greatest challenges in primary practice, especially in the geriatric population. It is typically detected by dipstick urinalysis, an ordinary, non-invasive test. Proteinuria is frequently a marker of unsuspected kidney disease, progressive atherosclerosis or a systemic disease. There is a strong correlation between urinary protein excretion and progression of renal failure. Furthermore, Proteinuria is a strong and independent predictor of increased risk for cardiovascular disease and death, especially in people with diabetes, hypertension, chronic kidney disease, and the elderly. This article will review the clinical significance of proteinuria in adults, especially in the elderly population, and provide a practical diagnostic approach in addition to a summary of non-specific antiproteinuric therapy.
Keywords: Proteinuria, Microalbuminuria, Macroalbuminuria, elderly, Risk Factor.

Case
You are seeing a 63-year-old lady with vague clinical symptoms, who was found to have a reading of 2+ proteinuria on urinalysis. She has been previously healthy and does not smoke tobacco or drink alcohol.

• What is the significance of proteinuria?
• What could be causing the proteinuria?
• How would you approach this case?
• How should this be managed now?
• When should this patient be referred for further investigation?

Introduction
Proteinuria is a common incidental finding in adult primary care practice, especially in the elderly population. Proteinuria is often transient and benign, but persistent proteinuria is not only a marker of early kidney disease, but also an independent risk factor for atherosclerotic diseases, such as coronary or cerebrovascular arterial diseases.¹ Individuals with proteinuria are at increased risk of death.^2-4 The incidence of proteinuria in randomly collected urine specimens increases with age and is significantly associated with increased mortality.⁵

Furthermore, persistent proteinuria is directly proportional to the extent of loss of renal function and is also a strong predictor for death related to cardiovascular diseases in the aging population, significantly adding to the already mounting burden from these diseases.⁶