Commonly used formulas for glomerular filtration rate include CKD-EPI, etc. Glomerular filtration rate varies in different ages, genders and populations. Normal blood creatinine and low glomerular filtration rate may be related to age, gender and so on. CKD-EPI formula is calculated by blood creatinine, gender, age and ethnicity. Normal blood creatinine and different age and gender may have low glomerular filtration rate. Low glomerular filtration rate may also be caused by pre-renal factors such as heart failure, and post-renal factors such as urinary tract obstruction. Heart failure patients have decreased cardiac function, insufficient effective circulating blood volume, and then insufficient renal blood perfusion, resulting in low glomerular filtration rate; patients with urinary tract obstruction have elevated blood creatinine, and the glomerular filtration rate will also be low. Patients with abnormal blood creatinine and glomerular filtration rate should go to the hospital in time and receive timely treatment under the guidance of professional physicians.