Renal Hypoplasia

Renal hypoplasia (failed development) of one kidney is uncommon, and hypoplasia of both kidneys is rare. It may be difficult to distinguish unilateral renal hypoplasia from a small kidney because of renal artery stenosis, obstruction or reflux nephropathy in early life.

Clinical interest in the condition most often arises in patients with hypertension, where the small kidney may be considered the cause. If the small kidney is shown by radioisotope studies to contribute no useful renal function, and if the hypertension has developed in a young subject or is difficult to control by medical treatment, nephrectomy should be undertaken.

Renal hyposplasia may also be associated with abnormalities of the ureter, the tube that connects the kidney to the bladder. This condition is marked by either a backflow of urine from the bladder into the kidney or an obstruction of the ureter at the juncture where it abnormally enters the kidney.

Diagnostic imaging, including computed tomography, of a two-month-old foal with renal failure indicated that its right kidney was probably absent and that its left kidney was abnormal in shape.

Renal hypoplasia does not appear to be an inherited condition nor does it occur more often in boys than girls. In fact, while the true incidence is unknown, it has been reported in as high as 2.5 percent of the population. The size of the kidney determines potential problems in the future.

Clinical research focuses on renal hypoplasia due to maternal Vitamin A deficiency, early ACE inhibitor intervention to prevent diabetic nephropathy and a novel therapy for hemolytic-uremic syndrome.