Kidney Disease Diagnosis and Management

Diagnostic Considerations

Immunofluorescence is recommended in specific scenarios, such as when glomeruli are lacking in frozen tissue samples or in patients with monoclonal gammopathy with C3 glomerulonephritis or unclassified proliferative glomerulonephritis, with a moderate level of evidence, as suggested by the American Society of Nephrology 1
IgA nephropathy diagnosis requires a kidney biopsy, with clinical features including nephritic urinary sediment, proteinuria, impaired renal function, arterial hypertension, and intermittent painless macrohematuria 2
Key diagnostic findings on kidney biopsy include immunofluorescence/immunohistochemistry showing mesangial dominant or co-dominant IgA deposits, and light microscopy showing variable mesangial hypercellularity, segmental glomerulosclerosis, endocapillary hypercellularity, tubular atrophy/interstitial fibrosis, and crescents (MEST-C scoring system) 2, 3
Electron microscopy may also show electron-dense deposits in the mesangium 3

The American College of Radiology recommends assessing kidney function through serum creatinine and estimated glomerular filtration rate (eGFR) for patients with IgA nephropathy 4
Blood urea nitrogen (BUN) is also a useful marker for kidney function assessment in IgA nephropathy patients 4
Serum electrolytes, including sodium, potassium, chloride, and bicarbonate, should be monitored in patients with IgA nephropathy 4
Serum calcium and phosphate levels are also important to monitor in IgA nephropathy patients, according to Nature Reviews Nephrology 1
A complete blood count (CBC) with differential and platelet counts is recommended for patients with IgA nephropathy, as suggested by the Journal of the American College of Radiology 4
Serum albumin levels should be monitored in patients with IgA nephropathy, particularly those with significant proteinuria, as recommended by the Journal of the American College of Radiology 4
Serum uric acid levels are also important to monitor in IgA nephropathy patients, according to Nature Reviews Nephrology 1
Serum and urine glucose levels should be assessed to evaluate for Fanconi syndrome in patients with IgA nephropathy 1
Lactate dehydrogenase (LDH) levels may be useful in monitoring disease activity in IgA nephropathy patients, as suggested by the Journal of the National Comprehensive Cancer Network 5

All patients with IgA nephropathy should receive optimized supportive care, including RAS blockade (ACE inhibitors or ARBs) for all patients with proteinuria >0.5 g/day, regardless of hypertension status (Grade 1B) 2, 6
Blood pressure control with targets of <130/80 mmHg if proteinuria <1 g/day and <125/75 mmHg if proteinuria ≥1 g/day is recommended 6
Sodium restriction (<2.0 g/day) is recommended to enhance antiproteinuric effects 2, 6
SGLT2 inhibitors may be considered as emerging therapy for renoprotection 2, 6
For patients with persistent proteinuria despite supportive care, a 6-month course of glucocorticoid therapy (Grade 2B) may be considered if proteinuria remains >0.75-1 g/day despite at least 90 days of optimized supportive care 2
Glucocorticoids should be avoided or used with extreme caution in patients with certain conditions, such as eGFR <30 ml/min per 1.73 m², diabetes, obesity, latent infections, secondary disease, active peptic ulceration, uncontrolled psychiatric disease, and severe osteoporosis 2

Regular monitoring should include proteinuria levels, renal function (serum creatinine, eGFR), blood pressure, and hematuria 2, 6
A reduction in proteinuria to under 1 g/day is a surrogate marker of improved kidney outcome in IgAN and represents a reasonable treatment target 2
Infection prevention measures, such as pneumococcal and influenza vaccines, should be considered, especially if immunosuppression is planned 2
The MEST-C histologic scoring system is used to evaluate mesangial and endocapillary hypercellularity, segmental glomerulosclerosis, interstitial fibrosis/tubular atrophy, and crescents, and helps estimate disease progression risk 2
The International IgAN Prediction Tool is also used to estimate disease progression risk 2