Nephritic vs Nephrotic Syndrome — Overview

Glomerulonephropathies affect glomerular structure and function, characterised by haematuria, red cell casts, or proteinuria. They’re classified into nephrotic syndrome, nephritic syndrome, or non-nephrotic proteinuria — though there is considerable overlap. See nephrotic-syndrome.md for detailed nephrotic-syndrome-specific complications and management.

Nephrotic syndrome

Proteinuria >3.5 g/1.73m²/24h, hypoalbuminaemia, oedema, hyperlipidaemia, lipiduria — practically, heavy proteinuria plus oedema from low albumin. Generally a non-inflammatory process.

Most common causes: diabetes (by far the most common), SLE, HIV/hepatitis B/C, focal segmental glomerulosclerosis, minimal change disease, membranous nephropathy, membranoproliferative GN.

Usually presents with oedema, or is picked up when checking for albuminuria in hypertension or diabetes.

Nephritic syndrome

Haematuria ± red cell casts, variable proteinuria, renal insufficiency, salt retention (hypertension and oedema). Characterised by an inflammatory process — this is how glomerulonephritis presents (see glomerulonephritis.md). May be intrinsic renal disease or secondary to a systemic cause.

Typically presents with oedema, oliguria, or hypertension; may be picked up incidentally as microscopic haematuria, or occasionally dark/tea-coloured urine.

Causes:

• Post-streptococcal glomerulonephritis — see post-strep-glomerulonephritis.md
• IgA nephropathy — the most common cause — see iga-nephropathy.md
• Lupus nephritis
• Rapidly progressive GN: anti-GBM disease (including Goodpasture syndrome), immune complex deposition disease (e.g. IgA vasculitis/HSP — see vasculitis.md)

Investigations

As for haematuria and glomerulonephritis generally: urinalysis + microscopy, ASO titre, anti-GBM antibody, ANCA, ANA, hepatitis serology (if risk factors or hepatomegaly), renal ultrasound. Kidney biopsy is often needed to make the diagnosis.

Management

Refer promptly — particularly urgently if rapidly progressive disease is suspected.