According to ISKDC (International Study of Kidney Disease in Children) it is defined as Proteinuria of more than 40 mg/M2/hr and Hypoalbuminaemia less than 2.5g/dl.
But for practical purposes it is defined as proteinuria more than 50 mg/kg/24 hours, serum total protein less than 5 G/dl, serum albumin less than 3 G/dl, hypercholesterolemia more than 220 mg/dl and with or without edema.
In children the commonest form of N.S. is primary nephrotic syndrome
Among these the MCNS is the most frequent.
Insidious onset of odema
Mild fever and Cold
Many children have recurrent episodes of such transient edema for many months.
Physical examination shows
Edema – The edema is initially noted around the eyes and in the lower extremidies where it is pitting in nature, with time edema becomes generalized and may associate with weight gain and the development of ascites, pleural effusion and decreased urinal output.
Fluid movements across capillary is normally the result of a balance between filteration and reabsorption, due to changes in capillary and tissue hydrostatic and oncotic pressure. It is still the pathogenesis of edema in NS is not well understood.
Because of the hypoalbuminaenia there is reduction in plasmo oncotic pressure leads to leak of fluid in to the interstitial compartment or accumulation of fluid secondary to sodium due to internal defect.
The major sites involved in the edema formation are:
1. Capillaries – where there is disruption of starling equilibiria
2. Kidney – where there is primary salt retension
According to the classical view
1. Vascular underfill hypothesis
2. Vascular overfill hypothesis
Vascular underfill hypothesis is responsible for the formation of edema.
Salt restriction is important to reduce edema. Idli, idiyappam, rice puttu, sweet pongal, coconut rice, curd rice, lemon rice, beet-root, chappathi, dhall, sugar candy, boiled potato, carrot, cabbage, tomato and onion are accepted. Start with salt free diet in the presence of edema and then slowly add salt.
Along with salt restriction water restriction is necessary to prevent dilutional hyponatremia. In mild edema intake is restricted to the urine output. In moderate edema intake is restricted to insensible water loss. In massive edema fluid intake is restricted to milk only equivalent to insensible water loss.
HDL levels are elevated in MCNS. Abnormal coagulability and glomerulus recrosis are consequence of lipid abnormalities. Weight control is essential. Diet should contain cholesterol less than 250 mg/day.
Secondary to hypoalbuminemia there is low ionic calcium, which is responsible for cramps and tetany. Hence calcium intake of 800 mg/day either by diet or tablet with Vit.D is necessary.
IRON & ZINC:
Iron supplementation is necessary in microcytic hypochromic anaemia. Rarely Zinc may be needed in the presence of deficiency symptoms.
Glucocorticoid has some influence on glomerular permeability. It blocks the action of migratory inhibiting factor (MIF) and chemotactic factor, inhibits the endothelial adherence of macrophages and leukocytes, blocks the antigen processing function of macrophage, stabilizes lysosomal membrane and prevents the increase in capillary permeability and diapedesis.
Prednisolone 2 mg/kg as a single or divided doses for 4 weeks then give 2mg/kg as single dose in the morning on alternate days for the next 4 weeks. Then taper prednisolone by 10mgm every 2 weeks. If there Is persistent proteinuria even after four weeks of daily therapy of steroid, continue the same dose for the next 4 weeks. If there is no remission even after 8 weeks of full dose of steroids, then lable the child as steroid resistant. In this type of cases steroids should be tapered to 0.5 mg/kg. Simultaneously add cyclophosphamide in a dose of 2 mg/kg/day. Care should be taken to have weekly W.B.C. count.
In case of steroid response but when there is frequent relapse prednisolone is to be given as 2 mg/kg for 4 weeks and then as a single dose in the morning on alternate day for 4 weeks. After 8 weeks of steroid therapy, it should be tapered but slowly so that the entire course lasts for 6 months. When the child is resistant to Predinosolone and Cyclophosphamise, Chlorambucil, 2-3 mg/kg is given for 10 weeks.