From the Guidelines
Nephritic range proteinuria is a significant indicator of glomerular inflammation and requires prompt evaluation and management to prevent progression to end-stage renal disease, with the most recent guidelines recommending renin-angiotensin system blockade and blood pressure control as initial therapy 1.
Definition and Causes
Nephritic range proteinuria refers to urinary protein excretion of less than 3.5 grams per 24 hours, typically between 0.5-3 grams daily, which occurs in the context of nephritic syndrome. This level of proteinuria is associated with glomerular inflammation and is distinguished from nephrotic range proteinuria (>3.5g/24h). Common causes include IgA nephropathy, post-infectious glomerulonephritis, lupus nephritis, and ANCA-associated vasculitis.
Evaluation and Management
Evaluation should include a urinalysis with microscopy (looking for red blood cell casts and dysmorphic red blood cells), urine protein quantification, serum creatinine, complement levels, and autoimmune serologies. Management depends on the underlying cause but often includes:
- Blood pressure control with ACE inhibitors or ARBs (such as lisinopril 10-40mg daily or losartan 25-100mg daily), which help reduce proteinuria and slow disease progression 1
- Immunosuppressive therapy may be necessary for autoimmune causes, with the most recent guidelines recommending combined immunosuppressive treatment with glucocorticoid and one other agent (e.g., mycophenolic acid analogs, cyclophosphamide) 1
- Patients should be monitored regularly with blood pressure checks, urinalysis, and kidney function tests
- Salt restriction (less than 2g sodium daily) and lifestyle modifications are also important components of treatment
- Early nephrology referral is recommended for proper diagnosis, often requiring kidney biopsy, and tailored treatment planning
Goals of Treatment
The goals of treatment include reducing proteinuria to less than 0.5-0.7 g/24 hours by 12 months, with at least 50% reduction in proteinuria by 6 months, and normalization or stabilization of GFR 1. The most recent guidelines emphasize the importance of achieving these goals to prevent progression to end-stage renal disease, with the use of renin-angiotensin system blockade and blood pressure control as initial therapy, and immunosuppressive therapy as needed 1.
From the Research
Significance of Nephritic Range Proteinuria
- Nephritic range proteinuria is a significant indicator of kidney disease, particularly glomerular damage 2, 3
- It is characterized by the presence of hematuria, proteinuria, hypertension, and in some cases, acute kidney injury and fluid retention 4
- Nephritic syndrome is a constellation of these symptoms, often resulting from acute glomerulonephritis 4
Relationship with Kidney Disease
- Nephritic range proteinuria is associated with an increased risk of progressive renal disease, including diabetic nephropathy 5, 6
- The presence of nephrotic range proteinuria is a strong predictor of rapid renal function decline in patients with severely impaired renal function 5
- Renal biopsy is essential in diagnosing and managing nephritic syndrome, as it can distinguish between diabetic nephropathy and non-diabetic renal disease 6
Clinical Implications
- Early detection and evaluation of proteinuria are crucial in preventing progressive disease, although the effectiveness of this approach is still unknown 2
- Patients with nephritic range proteinuria require careful evaluation and monitoring to determine the underlying cause and prevent further kidney damage 3
- Referral to a nephrologist is recommended for patients with suspected nephritic syndrome or persistent proteinuria 4