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Kidney Diseases

Duplicated Kidneys



My 6 yr-old daughter has just been diagnosed with duplicated kidneys (2 on the left side). Her pediatrician told me our only concern was to watch for UTI`s. How common are duplicated kidneys? Are there any increased health risks associated with this condition?


Duplicated kidneys (or partially duplicated) are not uncommon and can occur in up to 4% of the population. Most of the time they cause no problem at all, but as your pediatrician says, there may be an increased risk of infection or even blockage, depending on how the ureters (the thin tubes that connect the kidneys to the bladder) attach to the bladder. Sometimes only part of the kidney is duplicated, and both parts feed into the same ureter. Sometimes each duplicated kidney has its own ureter, and sometimes the ureter of one feeds into the ureter of the other (instead of each feeding directly into the bladder).

In the latter two conditions, there is sometimes an abnormal connection between the ureter and the bladder (or between the ureter and the other ureter), and urine can reflux, or flow backwards up the ureter instead of always downward from kidney to bladder. In that case, infections may be more common. I cannot tell what happened that caused your daughter to have the tests that discovered her duplicated kidney: did she already have an infection? In any case, signs to watch for include burning on urination, cloudy urine, and left flank pain (just below the ribs on the left side of the back), especially if it gets worse with drinking a lot of fluids.

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University