How Rare Is It To Be Born With One Kidney?

Our kidneys act as filtration devices. As part of the urinary tract, our kidneys rid our body of waste, excess fluid, and acid in the form of urine (via National Institute of Diabetes and Digestive and Kidney Diseases). Filtering through nearly a half cup of blood every 60 seconds, your kidneys also play a role in the creation of red blood cells, bone health, and blood pressure control.

Our kidneys form during the fifth to twelfth week of fetal development (via Minnesota Department of Health). While the body normally forms two kidneys, in some cases, only one kidney may develop during gestation, leading to a condition known as unilateral renal agenesis (via WebMD). While the exact cause of the condition is not well known, smoking or the use of certain medications or alcohol during pregnancy are thought to be contributing factors. Additionally, suggests a possible link between maternal diabetes and unilateral renal agenesis. So just how rare is it to be born with one kidney, and how does the condition impact one's health?

Can one kidney do the work of two?

While considered a rare medical condition (via WebMD), prevalence rates are not quite as rare as you might think they would be. Children's Hospital Los Angeles reports that as many as 1 in 1,000 babies are born with unilateral renal agenesis, and the condition is often diagnosed early via ultrasound. In the event that only one kidney has formed, it is referred to as a solitary kidney, per the National Institute of Diabetes and Digestive and Kidney Diseases.

Ultimately, life with one kidney does not differ much from life with two. Nurse practitioner in pediatric urology, Nicole Freedman, writes via the Children's Hospital Los Angeles blog, "The most important thing is this: Your child can live a long and healthy life with one kidney that works well." Freedman goes on to explain that this is because a solitary kidney will grow in size in order to take on the work of two.

While there are few long-term risks associated with unilateral renal agenesis, there is a small chance of mild progressive decline in kidney function — often occurring slowly over the course of 25 years or more (via National Kidney Foundation). For this reason, it's important to undergo a urine sampling and blood test every year by your doctor to monitor kidney function. In addition to routine check-ups, those with unilateral renal agenesis will also want to exercise caution when playing contact sports by wearing protective gear or padding.