Ans. (a) PSGNRef: Nelson Text book of Pediatrics 20th Ed; Page No-2498 & Ghats Essential Pediatrics 9th Ed; Page No-469* Most common cause of glomerulonephritis is immune mediated injury caused by Immune complexes and glomerular antigen mediated damage. It is characterized by the triad of hematuria, azotemia and hypertension.* The most common cause of acute glomerulonephritis is that following streptococcal infection (PSGN-Post streptococcal Glomerulonephritis).Post streptococcal Glomerulonephritis (PSGN)* Acute post streptococcal Glomerulonephritis is caused by autoimmune injury only due to selective nephritogenic strains of streptococcus.* The patient develops glomerulonephritis with streptococcal pharyngitis usually in winter after 1-2 weeks of infection and with streptococcal pyoderma in summer after 3-6 weeks of infection.* Nephritogenic strains include types 4 and 12 (pharyngitis) and type 49 (pyoderma).Clinical Features:* The most common age o presentation is 5-12 years (school- age children) and is rarely seen before 3 years of age.* The onset is rapid, with puffiness around the eyes and pedal edema.* The patient presents with gross hematuria with smoky, cola or tea colour urine and hypertension.* Peripheral edema typically results from salt and water retention.* Complications that can be seen are hypertensive encephalopathy, pulmonary haemorrhage, cerebral vasculitis, hyperkalemia, hypophosphatemia and acidosis.Diagnosis* Light microscopy: Proliferation of endothelial & mesangial cells* Fluorescence: Ig G, Ig M, and C3 deposits in mesangium.* RBCs casts on urine analysis is a characteristic feature* Urine shows 1-2+ proteinuria* Elation ASO titer (In skin infection ASO titre remains normal-here elevated anti-DNAse B titers help in diagnosis).Management* The treatment is usually suppurative most of the cases resolves spontaneously and rarely my progress to renal failure.* Close monitoring of blood pressure and diet (should be low in sodium and potassium).* Fluid restriction.* Diuretics (e.g. frusemide) for edema.* Penicillin is usually given for infection however it does not alter the course of glomerulonephritis.* Antihypertensive drugs (Amlodipine, nifedipine or diuretics); hypertensive emergencies need treatment with IV nitroprusside or labetalol.