Proteinuria - Renal Disease in Children

Renal Disease in Children

Proteinuria

·        Definition: > 150 mg protein/day (same cut off as adults)

·        Normally protein is lost from tubular cells.  Pathological if:

o   Filtered protein from glomerulus 

o   ­Loss from tubular cells

·        Categories:

o   Gross proteinuria: > 1 gm/day (® nephrotic syndrome if severe)

o   Acute low grade

o   Chronic low grade

·        Diagnosis: 

o   Dipstick: measures concentration of protein, so if urine is concentrated ® ­protein concentration as well 

o   24 hour urine: problem if not continent

·        Nephrotic syndrome: 

o  = Proteinuria + oedema + ¯albumin in blood (hypoproteinaemia) 

o  Oedema is due to ¯colloid osmotic pressure ® ­aldosterone ®­Na ® ­H2O retention ® this leaks out as well 

o  Caused by leaky glomeruli

Causes

·        Minimal Change Disease:

o  = No change under light microscope 

o  Passing up to 8 – 10 gm per day ® gross oedema

o  3 rare complications: 

§  Hypoperfusion: classically the gut ® abdominal pain

§  Loose Ig‟s as well ® ­risk of bacterial infection (eg pneumococcal)

§  Thrombosis (eg renal vein) 

o  Usually grow out of it (eg over 6 months, although may persist until an adult). Unpleasant but not usually life-threatening

o  Treatment: steroids but side-effects 

o  10 – 20% have other causes which may ® chronic renal failure

·        Acute low-grade proteinuria:

o  No long term significance

o  Can be:

§  Exercise induced in some teenagers/adults

§  Urinary tract infection

§  Postural proteinuria (­when standing up)

o  Have to demonstrate that it‟s gone (ie that its not chronic)

·        Persistent/chronic low grade proteinuria

o  Always have some.  Exclude exercise and postural 

o  Significant finding: ­risk of renal disease, eg in adult