Nephrotic syndrome presents with oedema, dipstick positive proteinuria, and a low serum albumin. Glomerulonephritis may present with nephrotic syndrome, or with less severe proteinuria, visible or non-visible haematuria and/or abnormal kidney function.
In adults there is a broad differential diagnosis, including a primary (see box 1) or secondary kidney disease (see box 2). Most adults will require a kidney biopsy to confirm the diagnosis and would normally be referred to a renal specialist.
There are some steps that can be taken in primary care to aid diagnosis and decide on the urgency of referral at a time during the COVID-19 pandemic when access to secondary care may be limited.
1. Assess kidney function. Patients with acute kidney injury (AKI) should be discussed urgently with a renal physician.
2. If limited support available, arrange the blood and urine tests outlined below as long as appropriate, practical and safe for the patient.
3. Manage oedema by advising on dietary salt restriction (no added salt and avoid high salt foods) and considering an oral loop diuretic (eg, furosemide 40 to 80 mg once a day adjusted according to response). Response is best monitored by the patient weighing themselves once a day at home. Aim for a weight loss of 0.5 to 1 kg/day, until there is minimal oedema or near usual weight if known. Avoid unnecessary fluid restriction, which may precipitate AKI.
4. There is a high risk of venous thromboembolism. Consider low-molecular-weight heparin if serum albumin <20 g/L (discuss this with renal physician). Product and dose should be adjusted for kidney function.
5. There is an increased risk of bacterial infection, especially streptococcal. Give pneumococcal vaccination if not up to date to reduce risk of infection.
6. DO NOT prescribe steroids unless the patient is known to have steroid responsive nephrotic syndrome. Use the minimum dose that previously induced remission and ensure that the patient knows that they are in a high-risk group for COVID-19.
Box 1. Primary glomerulonephritis that may present with nephrotic syndrome; blood and urine tests may help but a renal biopsy is usually needed for definitive diagnosis.
| Diagnosis | Typical features | Blood/Urine tests(U+E, LFT, bicarbonate, CRP, FBC, urine protein to creatinine ratio in all) |
|---|---|---|
|
Minimal change glomerulonephritis |
Proteinuria, no haematuria, normal GFR |
None, medication history |
|
Membranous |
Proteinuria, may have low level haematuria, any GFR |
PLA2R antibody (positive in 80% of cases), medication history |
|
Focal segmental glomeruloscerosis |
Proteinuria, no haematuria, any GFR |
HIV serology |
|
IgA nephropathy |
Proteinuria, haematuria (may be visible), any GFR |
Serum immunoglobulins |
|
Mesangiocapillary GN |
Proteinuria, haematuria, any GFR |
Serum immunoglobulins and electrophoresis, hepatitis B antigen, hepatitis C antibody, antinuclear antibody, complement C3 and C4, urine Bence Jones protein |
Box 2. Secondary glomerulonephritis that may present with nephrotic syndrome; blood and urine tests may confirm primary diagnosis, but a renal biopsy is usually needed for definitive renal diagnosis.
| Diagnosis | Typical features | Blood/Urine tests(U+E, LFT, bicarbonate, CRP, FBC, urine protein to creatinine ratio in all) |
|---|---|---|
|
Diabetic nephropathy |
Proteinuria, may have 1-2+ haematuria, any GFR |
HbA1c, fundoscopy |
|
Amyloidosis |
Proteinuria, any GFR History of plasma cell dyscrasia (primary amyloid) or chronic infection/inflammation (secondary amyloid) |
Serum immunoglobulins and electrophoresis, urine Bence Jones protein |
|
Systemic lupus erythematosus |
Arthralgia, skin rashes, lethargy, cytopenias |
Antinuclear antibody, complement C3 and C4 |
Dr Colin Jones is a consultant nephrologist at York Teaching Hospital NHS Foundation Trust
