Birth Defects Genital Urinary Tract Renal Agenesis

Renal agenesis, or kidney agenesis, is a birth defect of the kidneys. In this condition, improper kidney development in utero means that one or both kidneys fails to develop. Infants may have just one kidney affected by renal agenesis (unilateral), or bilateral renal agenesis, in which neither kidney forms.

What Do the Kidneys Do?

The primary job of the kidney is to filter waste and excess fluids from the body. The human body typically has two kidneys, and at least one kidney is necessary for normal body function.

The kidneys filter wastes that are then excreted in urine. If an absence or dysfunction of kidneys prevents this filtration, these wastes can build up in the body and become toxic. The kidneys also maintain blood pressure by filtering fluids out of the body.

Renal Agenesis in Newborns

Kidney agenesis may be detected using fetal ultrasound. When a prenatal diagnosis is made, the child can be monitored during the remainder of the pregnancy, and after birth to determine the best course of treatment. Infants with bilateral renal agenesis are immediately admitted to the neonatal intensive care unit. The state of function of other body systems and organs (including the lungs) is assessed.

Infants with kidney agenesis may be fed a special diet through a feeding tube. This diet is low in sodium and fluids, as these can cause high blood pressure because the body is unable to filter out excess fluid. Vitamin D and calcium supplements are important to maintain the proper balance of electrolytes.

Unilateral and Bilateral Renal Agenesis: Complications

In renal agenesis, unilateral cases are generally less serious. A child can lead a relatively normal life with unilateral renal agenesis; only one kidney is needed to perform all the necessary renal functions.

Prognosis for bilateral renal agenesis is usually poor. Infants often die of renal or respiratory failure in the first day of life, or they suffer complications during early childhood.

Chronic kidney failure can lead to:

  • Anemia
  • Excessive protein in the urine
  • High blood pressure
  • Poor growth.

Treatment Options for Kidney Agenesis

Affected individuals must undergo annual testing to monitor kidney function, as their bodies have no backup system if the sole kidney becomes diseased or infected. Individuals with unilateral renal agenesis may be advised to avoid a high-protein diet, as protein breakdown can stress the kidney.

Without kidney function, infants must be placed on dialysis, which performs the filtration duties of the kidneys. Infants and young children may receive kidney transplants. As with any surgery, survival depends on individual circumstances including response to treatments and the involvement of other body systems.


Basile, M. (2005). Renal agenesis.Retrieved April 17, 2010, from:

National Kidney and Urologic Diseases Information Clearinghouse (NKUIDC) (n.d.). Solitary kidney. Retrieved April 17, 2010, from:

Texas Department of State Health Services. (2007). Renal agenesis.Retrieved April 17, 2010, from: