Nephrotic Syndrome

Key Features

• Proteinuria > 3 g/day

• Albumin < 3 g/dL

• Peripheral edema

• Hyperlipidemia

• Oval fat bodies may be seen in the urine

• Most common cause is diabetes; other causes include

  • Minimal change disease

  • Focal glomerular glomerulosclerosis

  • Membranous nephropathy

  • Amyloidosis

Clinical Findings

• Peripheral edema with serum albumin < 3 g/dL

• Edema can become generalized

• Dyspnea caused by pulmonary edema, pleural effusions, and diaphragmatic compromise with ascites

Diagnosis

• Urinalysis: proteinuria; few cellular elements or casts

• Oval fat bodies appear as "grape clusters" under light microscopy and "Maltese crosses" under polarized light

• Serum albumin < 3 g/dL, serum protein < 6 g/dL

• Hyperlipidemia

• Elevated erythrocyte sedimentation rate

• The following tests may help elucidate the underlying cause of glomerular disease

  • Complement levels

  • Serum and urine protein electrophoresis

  • Serum free light chains

  • Antinuclear antibodies

  • Phospholipase A₂ receptor (PLA₂R) antibody titers

  • HbA_1c

  • Serologic testing for hepatitis B and C, HIV, and syphilis

• Kidney biopsy indicated in adults with new-onset idiopathic nephrotic syndrome if a primary renal disease is suspected

Treatment

• In those with sub-nephrotic proteinuria, dietary protein restriction may be helpful in slowing progression of kidney disease

• Salt restriction for edema

• Loop and thiazide diuretics in combination

• Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers

• Antilipidemic agents

• In patients with thrombosis, warfarin for at least 3–6 mo