I presume you’re talking about adult and not pediatric patients, where minimal change disease is the commonest cause and a therapeutic trial of prednisone is recommended before pursuing further investigations, after confirmation of nephrotic syndrome. Management of an adult patient presenting with nephrotic syndrome depends on the age and co-existing conditions. In adult patients, various glomerular diseases may present with nephrotic syndrome that may be primary or secondary. The secondary glomerulopathy may be due to diabetes, lupus nephritis or HIV disease. The common primary glomerular diseases are membranous glomerulonephritis, focal segmental glomerulosclerosis, and minimal change disease. In addition to baseline investigations — including assessment of renal function, urinary protein (by 24-hr urine collection or urine/protein ratio) and a renal ultrasound to assess echogenicity and renal size — the nephrologist should be involved in the care of these patients to establish an accurate diagnosis as the patient often would require a kidney biopsy. In addition investigations should include glycated hemoglobin, Anti-nuclear antibody, complement levels, serum albumin and fasting lipids, as often these individuals have hyperlipidemia. Further investigations may be required.
About 10% of adult patients with membranous glomerulonephritis may have underlying solid tumour, and minimal change disease may be associated with a lymphoproliferative disorder. These individuals should undergo age-specific screening to rule out a neoplastic process. In people where systemic symptoms are present then further investigations should be system-specific to assess for underlying neoplastic process. The treatment of these patients depends on the underlying cause and a majority may require immunosuppressive therapy, including steroids. More general measures include: effective blood pressure control, use of renin-angiotensin-aldosterone system inhibitor should be strongly considered to control urinary protein excretion rate, statins may be needed to control hyperlipidemia and often, anticoagulants in patients with heavy proteinuria because of the associated risk of thromboembolism.