|Other names: Multicystic dysplastic kidney, renal dysplasia, multicystic renal dysplasia|
|Diagram of multicystic dysplastic kidney|
|Complications||Hydronephrosis, high blood pressure, urinary tract infection, kidney failure|
|Risk factors||Family history, use of certain medications or drugs during pregnancy|
|Treatment||Follow-up, dialysis, kidney transplant|
|Frequency||1 in 4,000 newborns|
Kidney dysplasia, also known as multicystic dysplastic kidney (MCDK), is when the internal structures of one or both kidneys do not form properly during early development. If one kidney is affected, often there are no symptoms, though in some cases the kidney enlarges and causes pain. Complications can include hydronephrosis, high blood pressure, urinary tract infections (UTI), or kidney failure. If both kidneys are severely affected the child may die around the time of birth.
The cause includes a numbers of genetic mutations and exposure to certain drugs or medications during pregnancy. The underlying mechanism involves urine being unable to flow through the tubules within the kidneys resulting in cyst formation. Diagnosis is generally by ultrasound, either before or after birth.
If only a single kidney is affected and no symptoms are present follow-up to look for potential complications may be all that is required. If both kidneys are affected dialysis or a kidney transplant may be required. In some cases the affected kidney may shrink in size. Kidney dysplasia affects about 1 in 4,000 newborns. It was first described in 1836.
Signs and symptoms
When a diagnosis of multicystic kidney is made in utero by ultrasound, the disease is found to be bilateral in many cases. Those with bilateral disease often have other severe deformities or polysystemic malformation syndromes. In bilateral cases, the newborn has the classic characteristic of Potter's syndrome.
The bilateral condition is incompatible with survival, as the contralateral system frequently is abnormal as well. Contralateral ureteropelvic junction obstruction is found in 3% to 12% of infants with multicystic kidney and contralateral vesicoureteral reflux is seen even more often, in 18% to 43% of infants. Because the high incidence of reflux, voiding cystourethrography usually has been considered advisable in all newborns with a multicystic kidney.[medical citation needed]
The cause of multicystic dysplastic kidney can be attributed to genetics. Renal dysplasia can be a consequence of a genetic syndrome, which in turn may affect the digestive tract, nervous system, or other areas of the urinary tract. If the mother had been taking certain prescription drugs such as those for hypertension, this may be a precipitating factor as well.
The mechanism of multicystic dysplastic kidney is a result of an abnormal induction of metanephric mesenchyme. This could be a result of a formation difficulty of the mesonephric duct. Some mutations in genes associated with renal dysplasia (in syndromes) have been determined. The mutations in question occur at EYA1 or SIX1 genes (branchio-oto-renal syndrome). The PAX2 gene is also thought to play a role in MCDK.
The contralateral kidney often undergoes hypertrophy. This is believed to be a compensatory mechanism to the non-functional MCDK. About 90% of patients with an MCDK will have contralateral hypertrophy into adulthood. The impact of contralateral hypertrophy on long-term renal outcomes is unknown.
MCDK is usually diagnosed by ultrasound examination before birth. Mean age at the time of antenatal diagnosis is about 28 weeks A microscopic analysis of urine in individuals with probable multicystic dysplastic kidney should be done.One meta-analysis demonstrated that unilateral MCDK occurs more frequently in males and the greater percentage of MCKD occur on the left side of the body.
MCDK is not treatable. However, the patient is observed periodically for the first few years during which ultrasounds are generally taken to ensure the healthy kidney is functioning properly and that the unhealthy kidney is not causing adverse effects. In severe cases MCDK can lead to neonatal fatality (in bilateral cases), however in unilateral cases the prognosis might be better (it would be dependent on associated anomalies).
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