Hi Simona, Welcome to Healthcare Magic and thanks for your question... While it is true that stress can be an underlying factor in many diseases, it very unlikely that your pyelonephritis could have been caused by stress. Pyelonephritis is an infection of the kidneys and is caused by micro-organisms. Pyelonephritis presents with fever, painful urination, abdominal pain radiating to the back, nausea / vomiting, accelerated heartbeat and tenderness at the renal angle on the affected side. I am not clear as to why you had be taken to ER overnight, when you say that you did not have any symptoms of UTI... What was the reason you had to be taken to ER that night? I hope that you have taken adequate treatment, including appropriate antibiotics, for the pyelonephritis. It is also important to have an proper evaluation to see if you have any underlying causes / risk factors, so that you don t have a recurrence of the pyelonephritis. I also hope that you have been able to sort out your recent stressors and you are feeling comfortable. If you are finding things too stressful or difficult to cope, please do not hesitate to talk to someone, and if necessary, seek help from a professional. All the best. - Dr. Jonas Sundarakumar Consultant Psychiatrist