Q: My 18-month-old daughter kept a fever for a week, but didn't have a cold. Her doctor found infection in her urine. Does this mean she has bad kidneys? My grandmother had to go onto a kidney machine before she died.
A: Your daughter probably had what is called a urinary tract infection, or UTI. Most children with UTIs have perfectly normal kidneys before and after the infection. Sometimes the bacterial germs that cause the infection never reach the kidneys. The kidneys are high up in the back, under the ribs. Two long tubes, called ureters, carry urine from the kidneys to a muscular pouch in the pelvis called the bladder. Many urinary tract infections are confined to the urine that is in the bladder.
Sometimes, however, bacteria do reach one or both kidneys. Once there, they may cause permanent scarring if they invade the kidney tissue. Fortunately, these invading bacteria usually damage only a relatively small fraction of the child's to
tal kidney. People are born with more kidney tissue than they need, so the rest carries on quite nicely, even for a lifetime.
In most cases, it takes many severe kidney infections to lead to poor kidney function. Your grandmother's kidney failure was most likely caused by some other disease.
While we have been very optimistic about your child's kidneys, we do believe your doctor will want your daughter to have X-rays or an ultrasound study to be certain that her kidneys are of normal size and shape, that there is no obstruction to the free flow of urine and that urine is not backing up from her bladder into her kidneys (called reflux).
Doctors worry about long-term kidney damage much more when there is a combination of infection and obstruction or reflux, and follow such a child very closely, often consulting with a urologist. Sometimes surgery is required to prevent damage from infections, but only when the urinary tract is not normal.
Dr. Wilson is director of general pediatrics at the Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.