A 17-year-old patient is referred by his GP after presenting with periorbital oedema. The patient noticed the oedematous eyes 3 days ago, but repos feeling unwell since a throat infection 3 weeks ago with nausea and vomiting in the last week. A urine dipstick is positive for protein and blood while serum creatinine and urea are mildly deranged. The most likely diagnosis is:

C. (post strep. GN). This patient is suffering from post-streptococcal glomerulonephritis (C), which forms pa of the nephritic syndrome consisting of haematuria (micro- or macroscopic), hypeension, proteinuria and oedema. In severe cases, oliguria and uraemia can also occur. Patients usually suffer form a streptococcal infection 1-3 weeks prior to presenting with the above symptoms or signs of the nephritic syndrome. During this time, immune complexes are formed and deposited in the glomeruli causing damage. The nephrotic syndrome (A) involves albuminuria usually in the order of 3.5 g/d in adults causing oedema and is also associated with hyperlipidaemia (increased LDL/HDL ratio). Nephritic syndrome (B) involves haematuria (micro- or macroscopic) alongside hypeension and proteinuria. A Von Grawitz tumour (option D), otherwise known as renal cell cancer, typically occur in males (2:1 male to female ratio) originating from the proximal tabular epithelium. The average age of presentation is 50 years with symptoms including pain, haematuria and usually a mass in the flank alongside other symptoms of malignancy such as weight loss.