New Method Of Predicting Kidney Failure

Rhabdomyolysis (rab-do-my-AH-lo-sis) is the potentially deadly condition you probably never heard of. Literally meaning "dissolving muscle," rhabdomyolysis involves the leakage of potentially toxic proteins from damaged muscle cells into the bloodstream.

The kidneys work overtime to remove these protein-based toxins out of circulation but often work so hard that they fail, and dialysis is necessary to prolong life.

What Kinds of Conditions Cause Rhabdomyolysis?

Doctors first noticed that muscle injury could lead to kidney failure while treating soldiers who had suffered crush injuries during World War II. In the seventy-five years since the documentation of the first cases, physicians have come to realize that rhabdomyolysis is multifactorial, that is, it most often occurs when several kinds of injury to muscle occur at the same time.

Moreover, this kind of muscle tissue dissolution has different causes at different stages of life.

• In children, rhabdoymyolysis most commonly occurs after infection.

• In adults, rhabdomyolysis most commonly occurs after crushing injury.

• At any age, rhabdomyolysis can be a complication of a medical procedure gone wrong.

Broken bones can cause pressure on muscles that leads to muscle tissue breakdown. There are high rates of rhabdomyolysis after earthquakes. There are also high rates of the condition in traffic accidents.

Damage to blood vessels that supply the muscles after surgical clamping or trauma can trigger muscle breakdown.

And rhabdomyolysis can result from:

• Fever.
• Heart stroke.
• Cocaine abuse.
• Overdoses of "molly" or PCP.
• Near-drowing.
• Stroke.
• Extensive burns.
• Status epilepticus, that is, prolonged seizures.
• Immobilization or forced bed rest, especially after traumatic injury.
• Infections with Streptococcus, Staphylococcus, E. coli, fungi, yeast, and many other kinds of microorganisms.

What Is the Disease Process in Rhabdomyolysis?

Even though the dissolution of muscle tissue can be initiated by many different kinds of injuries and infections, the common denominator in rhabdomyolysis is damage to a part of the muscle known as the sarcolemma. The cell loses its ability to regulate the flow of electrically charged particles in and out, so its surface becomes less and less able to "grab" passing oxygen, amino acids, and glucose. Eventually the cell fills up with sodium (the positively charged ion from salt) and water and literally dissolves.

When this happens, the contents of the cell combine with hemoglobin in the bloodstream. Blood vessels tighten. The amount of fluid reaching the kidneys decreases. Free radicals form and attack the kidneys, which may cease to function.

Why the New Rating System May Prevent Kidney Failure Deaths

Traditionally, doctors have been on the lookout for kidney failure when they see the three classic symptoms of muscle tissue breakdown:

• Muscle pain.

• Fatigue.

• Dark urine.

When these three symptoms show up in someone who has been in an accident, or who has a broken bone, or who has been through a serious infection, a heart attack, a stroke, heat stroke, dehydration, or drug overdose, then doctors monitor kidney function to make sure the patient gets put on dialysis just as soon as it is needed.

The problem with relying on this triad of symptoms for beginning kidney care is that rhabdomyolysis doesn't always present itself with easily recognized diagnostic signs. Only about 50% of adults who go on to need renal dialysis show all three symptoms, and even fewer children who later need dialysis show all three. 

Extreme exercise, such as running a marathon, may present these three symptoms, but athletes may ignore them as normal. Someone whose muscles being to break down after an overdose of ecstasy, cocaine, or PCP isn't likely to appear fatigued. And when the underlying cause occurs during surgery, grogginess after anesthesia and painkillers and the nurse's inattention to urine output may delay recognition of the need for treatment.

Dr. Karandeep Singh (MD)'s new online calculation tool takes the guesswork out of predicting the need for dialysis.

Users of the tool simply click boxes for age, gender, and whether or not there is:

• Myositis (known muscle inflammation),
• Statin use,
• Seizure, or 
• Excessive exercise.

Then the user of the online risk assessment tool clicks boxes for several very common, objective laboratory measurements including:

• Creatinine,
• Calcium,
• CO2,
• CPK, and
• Phosphate.

The user clicks on the "calculate" button and the algorithm computes the probability of kidney failure.

It is not a substitute for medical diagnosis. If you get a low probability of kidney failure (and having played with the numbers, I can tell you it's impossible to make the algorithm predict a 0% risk of kidney failure), you still need your doctor's attention. You just probably don't have an urgent need to arrange for possible dialysis.

If you need dialysis and you don't get it, you will die.

Rhabdomyolysis is generally treatable when it is diagnosed in time. If you are concerned about whether your muscle injury or statin use might be causing you kidney injury, get a copy of your lab results and use the online calculator, linked below.

But don't use the calculator as a substitute for medical care. Use it to make sure you get all the medical care you need.