The components in the blood that might yield clues to how fast ALS is progressing are called albumin and creatinine. These components are normally tested to follow kidney and liver health, according to the U.S. National Library of Medicine.
But now it appears that these substances may be helpful for gauging the health of people with ALS, the new study suggests.
"The assessment of albumin and creatinine in the blood can reliably predict the prognosis of ALS at the time of diagnosis," said lead researcher Dr. Adriano Chio, a professor of neurology in the Rita Levi Montalcini department of neuroscience at the University of Torino.
The average survival of ALS patients is just one to three years after the diagnosis, according to background information in the study. Finding a simple way to predict progression of the disease might help doctors treat patients and help researchers evaluate new drugs, the study authors suggested.
"Currently, clinical trials rely on two main outcomes: survival, which is considered too rough and is largely biased by the different clinical practice of ALS centers; and the ALS functional scale, which has several limitations and is at least partly subjective. Researchers are actively looking for more objective [ways to predict] progression," Chio said.
Levels of albumin and creatinine might become a neurologist's tool for predicting patients' prognosis early in the disease, he said.
"In the research arena, albumin and creatinine could be used as [a way to track] disease progression in clinical trials for the discovery of new effective drugs for ALS," Chio added.
The report was published online July 21 in JAMA Neurology.
Dr. Ronald Kanner is chair of neurology at North Shore University Hospital and Long Island Jewish Medical Center in Manhasset, N.Y. He said the course of the disease is extremely variable. "Some patients succumb within a year and others progress very slowly, with 5 percent still alive after 20 years," Kanner said.
This great variability makes it difficult to judge the effectiveness of treatments aimed at slowing progression, he said. "The current study identified easily measurable substances in the blood that can give a clue to the severity of the disease and the impact of treatment," he added.
Kanner added: "ALS is a devastating disease that affects the nerve cells that control muscles. It causes progressive weakness and wasting of muscles and eventually leads to the inability to swallow or breathe."
For the study, Chio and colleagues looked at blood levels of albumin, creatinine, white blood cells, sugar, cholesterol and thyroid hormones in more than 600 people with ALS. They said they later validated their findings by duplicating the study in an additional 122 people with ALS.
Only levels of albumin and creatinine were related to survival in both men and women, according to the study findings. Lower levels of these substances were related to worse survival and muscle function.
Lower creatinine was related to a loss of muscle mass. And, lower levels of albumin were linked to increased inflammation, the investigators found.
The researchers suggest that longer-term studies following the levels of creatinine and albumin throughout the course of the disease would help better define their relationship to ALS symptoms and the progression of the disease.