Why Do Babies With CNF Need Their Kidneys Removed?

The thought of doctors removing your baby’s own kidneys is undoubtedly terrifying and can feel counterintuitive. However, in Congenital Nephrotic Syndrome of the Finnish type (CNF), removing the native kidneys (a procedure called nephrectomy) is often a life-saving necessity. The original kidneys have a broken filtration system that continuously leaks massive amounts of essential proteins out of the blood and into the urine ^[1]. This uncontrollable leak is impossible to sustain over the long term. Removing one or both kidneys stops the dangerous protein loss, stabilizes your baby’s nutrition and fluid balance, and creates a safer, predictable path to growing large enough for a kidney transplant ^[2][3].

The Danger of the “Leaky Filter”

In CNF, the kidneys’ filters (glomeruli) lack a crucial structural protein, meaning they cannot hold onto the body’s building blocks. Babies with this condition lose massive amounts of albumin (a protein that keeps fluid in the blood vessels), as well as antibodies that fight illness, factors that regulate blood clotting, and thyroid-carrying proteins ^[3][4].

Because of this constant loss, babies typically require daily intravenous (IV) infusions of albumin through a central venous line just to survive ^[5]. Despite this intensive medical support, the continuous protein drain puts babies at high risk for several severe complications:

• Severe Malnutrition and Growth Failure: When the body loses protein faster than it can be replaced, the baby cannot gain weight or grow properly ^[1].
• High Risk of Infection: The loss of antibodies, combined with the presence of a central IV line, makes babies highly vulnerable to life-threatening bacterial infections ^[6][3].
• Blood Clots: The body loses crucial “anti-clotting” proteins in the urine. Without these natural brakes on the clotting system, the baby’s risk for dangerous blood clots (thrombosis) drastically increases ^[7].
• Hypothyroidism: The loss of thyroid-binding proteins in the urine frequently leads to low thyroid function, meaning your baby will likely need thyroid hormone replacement medication for proper brain and physical development ^[4][8].

How Nephrectomy Changes the Course

Removing the kidneys stops the protein leak entirely ^[1]. While it is a major surgery with real risks, the long-term benefits for a baby with severe CNF are profound:

• Stopping IV Infusions: Once the leak stops, doctors can safely withdraw the daily albumin infusions ^[3].
• Removing Central Lines: Without the need for daily IV albumin, the central venous catheter can be removed, significantly lowering the risk of severe line-associated infections and blood clots ^[3][9].
• Stabilizing Growth: With nutrition finally staying in the body instead of being flushed out in the urine, the baby can absorb nutrients, gain weight, and grow ^[1][2].

One Kidney or Both?

Depending on your baby’s specific condition, the medical team may recommend different approaches:

• Unilateral Nephrectomy (Removing One Kidney): In early infancy, removing just one kidney can cut the protein loss in half ^[3]. This is often enough to reduce the need for albumin infusions and lower complication risks, delaying the immediate need for dialysis ^[3]. However, the remaining kidney will still leak, meaning your baby will still require ongoing medical management until the second kidney is eventually removed.
• Bilateral Nephrectomy (Removing Both Kidneys): For babies with severe, uncontrollable protein loss—often indicated when they need albumin infusions more than 14 days a month—removing both kidneys is required ^[5]. The average age for this procedure is around 9 months ^[10].
• Medical Management First: In some cases, doctors try to delay surgery using medications and intensive nutrition, but most children with the Finnish type will eventually require kidney removal to safely bridge them to transplant ^[10].

Understanding the Surgery and the Bridge to Transplant

It is completely normal to worry about putting a tiny, already vulnerable infant through major surgery. The nephrectomy requires general anesthesia, and the immediate postoperative period involves close monitoring in the intensive care unit to manage pain, fluid shifts, and blood pressure changes ^[11][12].

If both kidneys are removed, your baby will no longer produce urine. This is a massive shift in daily care: there will be no more wet diapers, and your baby will be put on strict fluid restrictions to prevent fluid from building up in their body. They will become dependent on dialysis (usually peritoneal dialysis, which uses the lining of the abdomen to clean the blood) ^[2].

While dialysis stops the chaotic, life-threatening protein loss and provides the stable environment needed for your baby to grow to the required size for a transplant (usually 1 to 2 years of age) ^[2], it is not an easy fix. Peritoneal dialysis requires intense daily care from parents at home, comes with a steep learning curve, and carries its own risks, such as abdominal infections (peritonitis). Your care team will provide extensive training to ensure you are fully prepared to safely manage this new normal at home before you are discharged.