The differences between nephrotic and nephritic syndrome are easily forgotten. At the most basic level, remember that nephrotic syndrome involves the loss of a lot of protein, whereas nephritic syndrome involves the loss of a lot of blood.
Nephrotic syndrome
The definition of nephrotic syndrome includes both massive proteinuria (≥3.5 g/day) and hypoalbuminaemia (serum albumin ≤30 g/L). 1
Proteinuria
- >3.5g in 24hrs
- ++++ Protein
- Urine looks frothy
- Tip: Nephrotic & Protein both have an “O” which may help you remember!
Hypoalbuminaemia
- Serum albumin ≤30 g/L
- Albumin is lost in the urine.
- Gaps in podocytes allow proteins to leak into the urine.
Oedema
- Albumin is lost in the urine.
- Hypoalbuminemia results in decreased intravascular oncotic pressure.
- As a result, fluid moves out of the intravascular compartment and into the surrounding tissues causing oedema.
Hyperlipidemia
- Due to hypoalbuminaemia, the liver compensates and increases production, however, this has the side effect of also increasing the production of lipids, hence causing hyperlipidaemia.
Nephritic syndrome
Haematuria
- +++ Blood – microscopic or macroscopic haematuria
- Red cell casts – distinguishing feature, form in nephrons and indicate glomerular damage
- Haematuria occurs due to podocytes developing large pores which allows blood and protein to escape into the urine.
Proteinuria
- ++ Protein (small amount)
Hypertension
- Usually only mild
Low urine volume <300ml/day
- Due to reduced renal function.
Differential diagnosis of Nephrotic and Nephritic syndrome
Nephrotic or nephritic syndrome can be caused by multiple disease processes. First deciding between nephritic and nephrotic syndrome is a useful starting point for your differential diagnosis. This is because each is associated with a particular subset of diseases. Below is just a quick overview of which diseases are associated with which syndrome, for more details read the Glomerulonephritis article.
Nephrotic syndrome – associated diseases
Primary causes
- Minimal change glomerulonephritis
- Focal segmental glomerulosclerosis
- Membranous glomerulonephritis
Secondary causes
- SLE
- Hep B and C
- HIV
- Diabetes mellitus
- Malignancy
Nephritic syndrome – associated diseases
- Post-streptococcal glomerulonephritis – appears weeks after upper respiratory tract infection (URTI)
- IgA nephropathy – appears within a day or two after a URTI
- Rapidly progressive glomerulonephritis (crescentic glomerulonephritis)
- Goodpasture’s syndrome – anti-GBM antibodies against basal membrane antigens
- Vasculitic disorder – Wegener’s granulomatosis, Microscopic Polyangiitis, Churg Strauss disease
- Membranoproliferative glomerulonephritis – primary or secondary to SLE, Hepatitis B/C
- Henoch-Schönlein purpura – systemic vasculitis – deposition of IgA in the skin and kidneys
References
- Nishi S, Ubara Y, Utsunomiya Y, et al; Evidence-based clinical practice guidelines for nephrotic syndrome 2014. Clin Exp Nephrol. 2016 Jun20(3):342-70. doi: 10.1007/s10157-015-1216-x.
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