GFR may decrease or increase after hydrocele is released from obstruction, it mainly depends on the cause of obstruction, the degree of obstruction and the duration of obstruction.GFR is glomerular filtration rate, which is used to assess renal function. If the patient’s renal function was normal in the past, acute obstruction leading to hydronephrosis can lead to impaired renal function, blood creatinine will rise and GFR will fall, in this case, after relief of the obstruction, the blood creatinine will slowly fall or even return to normal, and the GFR will rise to the normal value. However, if the obstruction is not relieved for a long time, or there has been atrophy of both kidneys, i.e., there has been a history of chronic kidney disease, in this case, even if the obstruction is lifted, the renal damage of the patient may continue to develop, and then the GFR may fall. In the presence of hydronephrosis, it is recommended to seek timely medical attention and active treatment under the guidance of a physician.