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.
Potty Training Start to Finish. Boys and girls are both developmentally ready to start potty training sometime between 18 and 30 months of age. The average age for boys to complete their training is 31 months old, according to the University of Michigan Health System. About 98 percent of kids are completely potty trained by 36 months of age, and the entire process typically takes three to six months.