Nephrotic Syndrome Flashcards
What is the diagnosis for nephrotic syndrome
- Proteinuria > 3g/24hr
- Hypoalbuminaemia <30g/dL
- Oedema
- Raised cholesterol
What is the mechanism of proteinuria
- Primary renal disease
- secondary caused
The normal physiolgoical asepcts of the bowmans capsule are disrupted which allow protein to leak through
Why dont we develop protienuira as a normal individual
- fenestrated endothelium of the capillaries
- basmenet membrane
- epithelial of the bowmans capsule - podocytes
What is the main protein in proteinuria/ glomuerular nephrotic syndrome
albumin
How do you assess proteinuria
Urine dipstick
24 hour urine collection
What is the gold standard for assessing proteinuria
24 hour urine collection
What does the urine dipstick test tell you
- tells you that protein is presnet
Name the levels of proteinuria
Negative Trace — between 15 and 30 mg/dL 1+ — between 30 and 100 mg/dL 2+ — between 100 and 300 mg/dL 3+ — between 300 and 1000 mg/dL 4+ — >1000 mg/dL
what concentration of substance is constant
creatine is constant irrespective of health and disease
How do you measure protein excretion with just a sample of urine
- Use the protein creatine ratio (PCR)
- Creatine remains constant irrespective of health and disease
- can be used to measure protein
How many grams a day of protein is 100mg/mmol
Urine PCR 100mg/mmol = 1g/24hour
How many grams of protein is supposed to be passed a day
3g/24hour
what are the two hypothesis as to why patients with nephrotic syndrome develop oedema
- Underfill hypothesis
- Overfill hypothesis - thought to be the predominant reasons why they get oedema
Describe underfill hypothesis (oedema development in nephrotic syndrome)
- Decrease in intravascular colloid osmotic pressure due to low serum albumin - Intravascular volume depletion
- Activation of the renin angiotensin system and retention of salt and water
Describe overfill hypothesis (oedema development in nephrotic syndrome)
Primary sodium retention
- due to the predominant mechanism of oedema in nephrotic syndrome, heart failure and liver failure
- as you retain sodium in the kidneys you thus retain water
- this means that water follows sodium into the intravascular compartment and this then moves into the extravascular compartment
- when the extravascular compartment expands, ANP is released to excrete water but ANP resistance develops
Describe how normal transcapillary oncotic pressure gradient works
- starlings law - mentions that it is the net between the hydrostatic and oncotic pressure that drives fluid movement between the inter vascular and interstitial compartments on the body
- Hydrostatic pressure is driven by the cardiovascular system
- hydrostatic pressure decreases as you go from the arterial end to the venous end
- the hydrostatic pressure in the interstitial compartment stays consent
- so the net hydrostatic pressure on the arterial end will drive fluid out whereas on the venous end it will drive fluid back in
- sodium is driven into the intravascular compartment
- water follows
- venous end fluid is pushed in
What is colloid osmotic pressure generated by
driven by negatively charged proteins in both the intervascular and interstitial compartments
What is the transcapillary oncotic pressure gradient
- Is the difference between the intravascular and interstitial COP
What does starlings law say
- mentions that it is the net between the hydrostatic and oncotic pressure that drives fluid movement between the inter vascular and interstitial compartments on the body
Describe the mechanism of action of nephrotic syndrome
- you loose colloid osmotic pressure due to lack of albumin and total protein in the intervascular
- therefore the colloid osmotic pressure exceeds the transcapillary hydrostatic pressure leading to retention of salt and water
- this leads to intravascular volume depletion
- activation of the RAAS
- leading to further water and salt retention
What is likely to be the predominant mechanisms for oedema in nephrotic syndrome
Overfill system
in a urine dip what is the presentation of nephortic syndrome
- protein
- in some cases blood
What investigations should you do in nephrotic syndrome
Urine
- protein/creatine raito
- microscopy (to rule out infection)
Blood investigations
FBC, clotting (may need a biopsy), urea and electrolytes
LFTs ( check for serum albumin result)
imaging
- US renal tract before biopsy
Renal biopsy
Name the primary and secondary causes of nephrotic syndrome
Primary
- Minimal change disease
- focal segmental glumerulosclerosis
- Membranous nephropathy
Secondary
- Diabetic nephropathy
- lupus nephritis
- pre-eclampsia
- amyloid
- congential nephropathy
