Aetiology, clinical manifestations, and diagnosis of nephrotic syndrome (NS) in children
Aetiology, clinical manifestations, and diagnosis of nephrotic syndrome (NS) in children
NS can be diagnosed by the fulfilment of 2 definitive criteria: urine protein excretion (NRP, nephrotic range proteinuria) >50 mg/kg/d. + hypoalbuminemia = defined as s. albumin <3 g/dL (30 g/L). NS can be induced by damage of the glomerular filtration barrier that causes increasing in its permeability. The most common type of childhood NS is the primary idiopathic NS. Its unique characteristic is diffuse foot process effacement on EM and minimal changes (called minimal change disease [MCD]), primary focal segmental GN (FSGS), or mesangial proliferation on LM. MCD is particularly likely in children under the age of 10 years.
Presentation of Idiopathic NS is generally with generalized oedema, primarily 1ST seen as periorbital oedema. This oedema can become generalized & massive (anasarca) leading to peripheral oedema, ascites, umbilical or inguinal hernia, scrotal or vulva swelling, and/or pleural effusion. Macroscopic haematuria & higher BP can be also observed. The finding of either one of these findings makes 👆 it less likely that MCD is the proper diagnosis, and another renal disease should be investigated.
DD: As children with NS initially presenting with generalized oedema, other aetiologies of childhood generalized oedema should be considered in the DD. NS can be differentiated from other causes of oedema by the finding of NRP >50 mg/kg/d and hypoalbuminemia <3 g/dL (30 g/L):
(1) Heart failure
(2) Other causes of hypoalbuminemia, e.g. protein-losing enteropathy or protein malnutrition (kwashiorkor). Hypoalbuminemia can be also observed in children with cirrhosis, where the main cause of fluid retention is PH (portal hypertension).
(3) Higher capillary permeability due to an allergic reaction or hereditary angioedema. The oedema in these disorders is typically 👉 focal.
Initial lab profiles confirm the Dgx of NS and may also be utilized to diagnose specific underlying aetiology of NS. In children with NS who have a high probability of diagnosing MCD depending upon both clinical & lab findings, it is recommend too commence empiric therapy of oral prednisone, to avoid kidney biopsy. Kidney biopsy is usually proceeded in ptns with failure of response to steroid therapy (steroid-resistant NS) and in those who’re less likely to initially respond to steroid therapy. The DD includes other nephritides presenting with oedema; these disorders can be easily differentiated from NS by the finding of NRP (nephrotic range proteinuria) in addition to hypoalbuminemia.
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