A 24 y.o. patient complains of nausea, vomiting, headache, shortness of breath. He had an acute nephritis being 10 y.o. Proteinuria was found out in urine. Objectively: a skin is grey-pale, the edema is not present. Accent of II tone above aorta. BP 140/100-180/100 mm Hg. Blood level of residual N2- 6,6 mmol/L, creatinine- 406 mmol/L. Day's diuresis-2300 ml, nocturia. Specific density of urine is 1009, albumin- 0,9 g/L, WBC- 0-2 in f/vis. RBC.- single in f/vis., hyaline casts single in specimen. Your diagnosis?