My Mom Had Creatinine 0.89 In July And Her GFR

My mom had Creatinine 0.89 in July and her GFR was always above 60(60>)..then did CT with contrast in August..in January her Creatinine was 1.3 and GFR was 39 suddenly. Then in February she had Colonoscopy had PEG 3350 Sodium Chloride, Sodium Bicarbonate and Potassium Chloride for Oral Solution. Next day after colonoscopy was sick for couple days. Then in March she went to hospital because she had Flu and her Creatinine was 2.7 and GFR was 21. Could CT and the solution killed the kidneys?