ALS Patients Show Altered Levels of Iron Status Indicators, Study Reports

The levels of certain indicators of iron status, namely ferritin and transferrin, are altered in patients with amyotrophic lateral sclerosis (ALS) relative to healthy controls, suggesting a possible link between iron metabolism and ALS, a study has found.

The results, “Abnormal Serum Iron-Status Indicator Changes in Amyotrophic Lateral Sclerosis (ALS) Patients: A Meta-Analysis,” were published in the journal Frontiers of Neurology.

Recent studies suggest that abnormal iron metabolism is linked to neurodegenerative disorders, including ALS. Iron is a key element for the human body to function well and is pivotal to maintain normal brain function.

In fact, indicators of iron levels in the body, such as ferritin, have been proposed as biomarker for ALS. Ferritin is a major storage protein for iron and plays a key role in the iron recycling pathway.

However, evidence so far has been contradictory: while some studies suggest a link between abnormal iron metabolism and ALS, others have found evidence supporting this link.

Now, a group of Chinese researchers searched several electronic databases, including PubMed, Embase, and Cochrane Library, as well as library collections, to find studies (published until March 31, 2019) that reported on iron metabolism and ALS.

A total of 11 studies (five cohort studies and six cross-sectional studies) were included in this analysis, totaling 1,599 ALS patients and 1,255 controls. The studies were conducted in Europe (five studies), China (three studies), Japan (one study), and the U.S. (two studies).

The majority of the studies (eight) included ferritin as an indicator of iron metabolism. After analyzing these data, researchers found that the levels of ferritin were significantly higher in ALS patients.

“[W]hether the elevated ferritin is a protective or risk factor of disease is still unclear, and further exploration of the molecular mechanism is needed. From our study, ferritin could potentially be used as a screening biomarker of ALS at least,” the researchers wrote.

The levels of transferrin, an important iron transport protein, were decreased in ALS patients (both in men and women) compared with controls. Transferrin’s ability to reduce the levels of free iron in circulation suggest that this protein could have a protective effect for neurons in the context of ALS.

“Our study showed that transferrin level was lower in ALS patients than in controls, prompting the idea the lower transferrin was associated with increased risk of developing ALS,” they added.

Based on data from seven studies that measured the levels of blood iron, researchers found no differences between ALS and controls. This was true when looking at iron levels in men and women separately.

Overall, “our results showed that serum ferritin level was higher and transferrin level was lower in ALS patients compared with healthy controls, while there was no statistical difference in iron between ALS patients and healthy controls,” the researchers wrote.

“Further prospective and multi-centered studies of the changes of iron-status indicators and role of iron metabolism in ALS are needed,” they concluded.