A 5-year-old boy from Chaozhou, Guangdong province, recently phoned a local hospital to enquire about the procedure to donate his kidney to his bedridden mother, who suffers from uremia.

The boy, who needs a stool to reach the stove, has been cooking for his mother for months since his father left for another city to work.

He recently phoned a hospital, admitting he had no idea what was wrong with his mother but certain that he wanted to give her his kidney.

The boy's mother, however, is sure her end is just around the corner. She has even started writing postdated letters to her son.

One of such letters, dated 2012, reads: "My dear son, I miss you very much. But I cannot come home because my place of work is very far. Learn to be tolerant in your life and study hard at school."