Nephrotic syndrome, NS

Notes

## Basic introduction:

  • NS is a renal syndrome that is common in pre-school and school age children that and it is characterized by generalized edema, proteinuria and hypo-albuminemia
  • In NS, there is inflammation of podocytes, which are cells lining the Bowman's capsule. This leads to the loss of proteins from the blood through urine. Also due to the reduced oncotic pressure in the blood because of proteinuria, sodium retention in the distal nephron and increased secretion aldosterone, edema occurs.
  • Due to the urinary immunoglobulin loss, patients with NS tend to have reduced resistance to infections.

## Primary causes of NS:

  • Minimal change disease (the most common cause of the nephrotic syndrome in children)

_There are no microscopically visible changes in the glomerulus on microscopy

_It is managed with corticosteroids

_It does not progress to chronic renal disease

  • Focal segmental glomerulosclerosis (the most common primary cause of idiopathic nephrotic syndrome in adults).

_This is associated with sclerosis (hardening) of parts of some glomerulus

_Its causes include HIV, heroin abuse and idiopathic

_Corticosteroids can provide some relief

_50% of cases will end up with renal failure

  • Membranous glomerulonephritis, MGN

_It can manifest either nephrotic or a nephritic feature

_It is caused by auto-antibodies to phospholipase A2 receptor (2/3 of cases), cancers of the lungs, cancers of GIT, hepatitis B virus infection, malaria, penicillamine, systemic lupus erythematosus and cerebral shunts among others.

_The pathology of MGN involves thickening of glomerular basement membrane with minimal hyperproliferation of the glomerular cells. Features of Type III hypersensitivity reaction are also evident.

_1/3 of patients remain with the disease, 1/3 remit, and 1/3 progress to end-stage kidney failure.

  • Thin basement membrane disease

_This is an autosomal dominant inherited disease characterized by thin glomerular basement membranes

_It is a benign disease with key presentations of persistent microscopic hematuria as well as mild proteinuria.

_It shows very good prognosis.

## Secondary causes of NS:

  • Diabetes mellitus (which is the main cause of secondary NS in adults)
  • Amyloidosis
  • Infections such as malaria, HIV, schistosomiasis, filariasis, hepatitis (B & C), mycoplasma, syphilis and toxoplasmosis
  • Transplant rejection
  • Pre-eclampsia
  • Toxins such snake bites and phytotoxins
  • Cancers from any part of the body
  • NSAIDS, captopril, penicillin and other drugs
  • Sickle cell disease, Alport's syndrome, hereditary nephritis and other inherited diseases
  • Collagen vascular diseases such as SLE, rheumatoid arthritis, polyarteritis nodosa among others
Symptoms
  • NS is characterized by massive proteinuria (≥3.5 g/day) and hypoalbuminemia (serum albumin ≤30 g/L)
  • Marked to massive edema (in children, periorbital edema is usually the first presenting feature of NS while peripheral edema affecting the ankles and legs are the first presenting feature in adults).
  • Hyperlipidemia (and other dyslipidemia)
  • Abnormalities in coagulation or fibrinolysis (which can cause deep vein thrombosis and myocardial infarction)
  • Apnea (mainly due to pulmonary embolism)
  • Leukonychia (white nails or milk spots)
Diagnosis
  • Clinical review
  • 24-hr urine output
  • Urinalysis
  • Urea & Electrolyte
  • Serum cholesterol
  • Renal ultrasound
  • Renal biopsy (where necessary)
  • Random Blood Sugar (RBS)
  • Erythrocyte sedimentation rate (ESR),
  • Testing for other infections such as HIV, syphilis and hepatitis (B & C) infections
  • FBC
  • Coagulation test
  • LFTs
  • Bone profile (by determining serum calcium, phosphate and alkaline phosphatase levels)
  • CT and MRI scanning of the abdomen (where renal vein thrombosis is suspected)
Differential
  • Acute Kidney Injury (AKI)
  • Antiglomerular Basement Membrane Disease
  • Chronic Glomerulonephritis
  • Diabetic Nephropathy
  • Ischemic nephropathy
  • Multiple Myeloma
  • Nephrolithiasis
  • Nephrosclerosis
  • Chronic Kidney Disease
  • Obstructive uropathy
  • Rapidly Progressive Glomerulonephritis
Prevention
  • Immunization especially against Pneumococcus
  • Prevention depends on the underlying cause
Management
  • Low protein and salt diet
  • Drugs that are likely to be used include:

_Diuretic therapy with Furosemide about 1 mg/kg/day with or without Spironolactone (2 mg/kg/day).

_IV albumin therapy in cases of extensive hypoalbuminemia (where the response to diuretic treatment is generally poor)

_Antibiotics (when infection is suspected or there is a need for prophylaxis)

_Corticosteroid therapy for 2-3 months may give some remission

_Immunomodulatory drugs such as cyclosporine, cyclophosphamide, and tacrolimus may be beneficial in patients who respond poorly to the steroid therapy.

_ACE inhibitors and ARBs can give provide some improvement of the outcome especially in adults

_Alpha D3

_Nephrectomy (rarely)

_Statins (for treatment of dyslipidemia)

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