In medicine, the BUN-to-creatinine ratio is the ratio of two serum laboratory values, the blood urea nitrogen (BUN) (mg/dL) and serum creatinine (Cr) (mg/dL). Outside the United States, particularly in Canada and Europe, the truncated term urea is used (though it is still the same blood chemical) and the units are different (mmol/L).
Your child must be both physically and emotionally ready for toilet training. Most children are ready to start when they are between 22 and 30 months of age, but every child is different. Toilet training usually becomes a long and frustrating process if you try to start it before your child is ready.
Today, the average age for potty training is about 30 months with the age ranging from 18-60 months. Also, today the child centered approach to potty training is popular; respect your child's wishes and needs; wait until your child is ready; don't force the issue of potty training just relax and use pull-ups; your child will use the potty when s/he is ready to use!!