Female, 27 years old, previously healthy, felt sore throat after cold (examination at that time: red throat, tonsils once enlarged), fever for 1 day, maximum temperature 39.3 degrees, self-administered amoxicillin, temperature dropped to 38 degrees on the second day, still had sore throat (an ulcer of about 0.5 cm in diameter was visible on the tonsils), felt soreness in the back, felt deepening color of urine, morning urine routine on the third day showed: occult blood ++, bilirubin +, protein ++, microscopy: WBC 20/ul, epithelial cells 0/ul, RBC full field of view/ul, RBC tubular one. On the third day, the morning urine routine showed: occult blood ++, bilirubin +, protein ++, microscopy: WBC 20/ul, epithelial cells 0/ul, RBC full field of view/ul, RBC tubular one can be seen. The rest was approximately normal. At this time, there was no fever, and he felt soreness and swelling in his back. The renal function was normal. After taking ciprofloxacin for 3 days, the urine routine was repeated: protein-, occult blood ++, no tubular pattern on microscopic examination, occasional WBC, RBC decreased compared with before. After stopping ciprofloxacin for 1 day, the morning urine routine was rechecked 2 days later: protein -, occult blood +, no tubular pattern on microscopy, occasional WBC, RBC decreased significantly, 10/ul. The rest was not significantly abnormal. The rest of the urine was unremarkable. The urinary phase contrast microscopy: WBC 1400/ml, RBC 12,600/ml, protein (+), RBC non-glomerular 12%, glomerular 88%. Blood antinuclear antibody: negative. 3 days later, urine phase contrast microscopy: RBC 34.50/ul (?34.50/ul?, normal reference value: 0-17.6), RBC high magnification field 6.2HPF (normal reference value: 0-3.17), RBC non-glomerularity 5%, glomerularity 95%, the rest normal. After 2 weeks of rest, urine phase contrast microscopy was repeated: RBC 353.90/ul, RBC high magnification field 63.8HPF, RBC glomerular 100%, the rest normal. After one week of amoxicillin, rutin and nephritis rehabilitation tablets, the urine was re-examined: RBC 253.20/ul, RBC high magnification field 45.6HPF, RBC glomerularity 95%, non-glomerularity 5%, the rest normal. 24-hour urine protein quantification: normal (54.08mg). I. Discussion: Case characteristics: young female, 2 days after upper respiratory tract infection with or without proteinuria, no swelling, blood pressure, renal function is unknown (not mentioned as normal by default), repeated urine red blood cell morphology indicates glomerular origin, clinical diagnosis consider occult glomerulonephritis, pathological type consider the possibility of IgA nephropathy II. differential diagnosis 1, acute glomerulonephritis, often for infection The diagnosis of acute glomerulonephritis, often with abnormal urinalysis 1-3 weeks after infection, often with swelling and high blood pressure, can be checked for anti-O and complement concordance; 2, allergic purpura nephritis, can be asked whether there is a rash, abdominal pain, diarrhea and other allergic manifestations; 3, lupus nephritis: can be asked whether there are other manifestations of multi-system damage, but ANA negative, does not support; 4, hepatitis B-associated nephritis: with or without a history of hepatitis B, check the hepatitis B two-to-one half. A kidney biopsy is required for a definitive diagnosis.