Four things to know about your child’s kidneys

illustration of two kidneys dressed as construction workers
(F. Gracey/Boston Children's)

If you’re like most parents, you probably know that the kidneys filter waste from the body and produce urine. But fewer people understand the full extent of the role that these bean-shaped organs play in our health. “When we meet with families, we typically educate them on all the responsibilities that kidneys have in the body,” explains Dr. Deborah Stein, a nephrologist and co-director of the Midaortic Syndrome and Renovascular Hypertension Center at Boston Children’s Hospital. Here, she and the center’s other co-director, nephrologist Dr. Michael Ferguson, share some fascinating facts about our kidneys — and explain why they’re integral to the health of both kids and adults.

1. Your child’s kidneys are hard at work — even before birth.

The kidneys begin to form as early as the fifth week of gestation, and start producing urine by the ninth week. In fact, the amniotic fluid that surrounds the fetus during pregnancy is made up mostly of the baby’s own urine. “Each kidney should contain about one million filtering units called nephrons,” says Dr. Stein. “If a child is born with a lower number of filters, the kidneys have to work harder to keep everything balanced, and it is more likely the child will have medical issues related to the kidneys.” However, kidney disease can have many different causes and usually has few noticeable signs and symptoms.

2. Kidneys are multitaskers.

The kidneys do a lot more than most of us realize. In addition to removing waste and extra fluid from the body, they help maintain a healthy balance of electrolytes, including sodium, calcium, potassium, and phosphorus, says Dr. Ferguson. The kidneys also send signals to the bone marrow to make red blood cells and help keep your child’s bones strong.

3. Kidneys help control blood pressure.

Along with their many other responsibilities, the kidneys produce hormones that help regulate blood pressure. Abnormalities within the kidneys or the blood vessels leading to them can cause high blood pressure: For example, a conditioned called renal artery stenosis — narrowing of the vessels that carry blood to the kidneys — can lead to increased blood pressure in children, a condition known as renovascular hypertension.

Your child’s primary-care provider should check his or her blood pressure at every routine well-child visit for kids age 3 and older, and more often in kids with certain risk factors, such as a history of prematurity, obesity and diabetes. If the clinician suspects that high blood pressure may be due to an underlying condition such as kidney disease, they may refer you to a nephrologist or other specialist.

4. Kidney disease is often treatable.

Kidney disease can have a wide variety of causes, including hereditary diseases, congenital defects, systemic diseases, nephrotic syndrome, infection, and trauma. The good news: Many forms of kidney disease can be well managed with medications, while dialysis and transplant are treatment options for children with chronic kidney failure. “One of the reasons that I became a nephrologist is because kidney disease is often very treatable,” says Ferguson. “Our primary goal is for kids to be out of the hospital and enjoying their lives.”

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