Hemolytic uremic syndrome (HUS) is a potentially fatal complication of E. coli O157:H7 infection, most common in children. At Marler Clark, we too often have to explain HUS to the lawyers and insurers for companies that have sold contaminated food.

Acute renal failure is one of the signature elements of HUS. Many of those who develop HUS must receive dialysis to survive. Most of those that survive the acute phase of HUS regain enough renal function to abandon dialysis, at least for a time.

One of the most disheartening aspects of the syndrome, however, is the irreversible damage done to the kidneys during the acute stage. The damage sustained in the short term then places the patient at risk for long term renal complications, including end stage renal disease (ESRD). That damage to the kidney is referred to as a "hyperfiltration injury."

Hyperfiltration injury is a term used to describe chronic, progressive damage in kidneys that have already sustained a severe acute injury (such as in HUS) that results in the destruction of a substantial percentage of nephrons.   Nephrons are the functional units of the kidney and are comprised of glomeruli connected to renal tubules.

The remaining functional glomeruli attempt to adapt to their reduced number by enlarging (hypertrophy) and by hyper- filtrating (i.e., the remaining glomeruli work extra hard) in an attempt to meet the needs of the body. For a time, they are usually able to compensate, but they are being “over worked”, and their “cry for help” is manifested by the spillage of protein (albumin) in the urine (proteinuria).

As time passes, the hyperfiltration injury causes progressive loss of the remaining glomeruli due to fibrosis (scar tissue formation). And, in time, once the remaining functional nephron population drops below 10 percent, the person’s survival requires initiation of “renal replacement therapy”.

The use of an angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) is usually helpful in slowing the fibrotic process, but no known treatment can stop it. ESRD, also known as stage 5 kidney disease, eventually occurs.

Once ESRD is reached there are two survival options, neither enticing. The patient must then receive long-term dialysis treatment or a renal transplant.