About kidney agenesis

What is kidney agenesis?

Bilateral Renal Agenesis is the absence of both kidneys at birth. It is a genetic disorder characterized by a failure of the kidneys to develop in a fetus. This absence of kidneys causes a deficiency of amniotic fluid (Oligohydramnios) in a pregnant woman. Normally, the amniotic fluid acts as a cushion for the developing fetus. When there is an insufficient amount of this fluid, compression of the fetus may occur resulting in further malformations of the baby.

This disorder is more common in infants born of a parent who has a kidney malformation, particularly the absence of one kidney (unilateral renal agenesis). Studies have proven that unilateral renal agenesis and bilateral renal agenesis are genetically related.



What are the symptoms for kidney agenesis?

Both types of renal agenesis are associated with other birth defects, such as problems with the:

  • lungs
  • genitals and urinary tract
  • stomach and intestines
  • heart
  • muscles and bones
  • eyes and ears

Babies born with URA may have signs and symptoms at birth, in childhood, or not until later in life. Symptoms can include:

  • high blood pressure
  • poorly working kidney
  • urine with protein or blood
  • swelling in the face, hands, or legs

Babies born with BRA are very sick and do not usually live. They typically have distinct physical features that include:

  • widely separated eyes with skin folds over the eyelids
  • ears that are set low
  • a nose that is pressed flat and broad
  • a small chin
  • defects of the arms and legs

This group of defects is known as Potter Syndrome. It occurs as a result of reduced or absent urine production from the fetal kidneys. The urine makes up a large part of the amniotic fluid that surrounds and protects the fetus.



What are the causes for kidney agenesis?

Both URA and BRA occur when the uretic bud, also called the kidney bud, fails to develop at an early stage of fetal growth.

The exact cause of renal agenesis in newborns is not known. Most cases of renal agenesis are not inherited from the parents, nor do they result from any behavior by the mother. Some cases, however, are caused by genetic mutations. These mutations are passed on from parents who either have the disorder or are carriers of the mutated gene. Prenatal testing can often help determine if these mutations are present.



What are the treatments for kidney agenesis?

Most newborns with URA have few limitations and live normally. The outlook depends on the health of the remaining kidney and the presence of other abnormalities. To avoid injuring the remaining kidney, they may need to avoid contact sports when they’re older. Once diagnosed, patients of any age with URA need to have their blood pressure, urine, and blood tested annually to check kidney function.

BRA is typically fatal within the first few days of a newborn’s life. Newborns usually die from underdeveloped lungs shortly after birth. However, some newborns with BRA survive. They must have long-term dialysis to do the work of their missing kidneys. Dialysis is a treatment that filters and purifies the blood using a machine. This helps keep your body in balance when the kidneys can’t do their job.

Factors such as lung development and overall health determine the success of this treatment. The goal is to keep these infants alive with dialysis and other treatments until they grow strong enough to have kidney transplants.



What are the risk factors for kidney agenesis?

Risk factors for renal agenesis in newborns appears to be multi-factorial. This means that genetic, environmental, and lifestyle factors combine to create a person’s risk.

For example, some early studies have linked maternal diabetes, young maternal age, and alcohol use during pregnancy to renal agenesis. More recently, studies have shown prepregnancy obesity, alcohol use, and smoking to be linked to renal agenesis. Binge drinking, or having more than 4 drinks over 2 hours, during the second month of pregnancy also increases risk.

Environmental factors may also result in kidney defects like renal agenesis. For example, maternal medication use, illegal drug use, or exposure to toxins or poisons during pregnancy may be factors.



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