Today, we discussed the case of a young man with nephrotic-range proteinuria.
3 key pearls:
- There are three main diseases that can cause a mixed nephritic/nephrotic syndrome:
- Membranoproliferative glomerulonephritis
- IgA nephropathy
- Untreated diabetic nephropathy alone can cause severe, nephrotic-range proteinuria!
- Advanced cases of nephrotic syndrome can result in proximal renal tubular acidosis, resulting in glucosuria (as seen in our patient today).
For those interested in specifics of Nephrotic Syndrome…
- Definition: > 3.5 g urine protein/day, hypoalbuminemia (< 3 g/dL), peripheral edema
- Differential Diagnosis
- Primary Renal: Membranous, minimal change, FSGS, Membranoproliferative, IgA nephropathy
- Secondary/Systemic Causes: DM, SLE, Amyloid, infections, malignancy, amyloid
- Other associated findings: acute kidney injury (not always), thromboembolism (renal vein thrombosis is found disproportionately in patients with membranous nephropathy), infection (due to urinary loss of immunoglobulins), proximal tubular dysfunction.
- Biopsy can often be necessary to reveal the definitive diagnosis. (note this is in contrast to nephritic syndrome, which can be diagnosed with examination of the urine sediment and blood work: serologies). Interestingly, Richards, et al* found that in 28 patients with nephrotic range proteinuria, histologic information obtained via biopsy altered management in 24/28 cases (86%!!!)
- Treatment: Diuretics (treat edema), Ace-inhibitor (proteinuria), statin (hyperlipidemia), anticoagulation (hypercoagulability)
Richards, NT, Darby S, Howie AJ, Adu D, Michael J. Knowledge of renal histology alters patient management in over 40% of cases. Nephrol Dial Transplant. 1994;9(9);1255