Lupus, Fatigue, Muscle Weakness
By A. G. Moore
A 2012 study conducted in Australia looked at the relationship between muscle strength and fatigue in women with SLE. Since fatigue is a symptom reported by more than 50 % of patients with SLE, researchers tried to determine if the fatigue was due to reduced muscle strength.
This study was small–45 women, 24 with SLE and 21 who were “healthy”. There were two measures of muscle strength examined: functional and isometric maximal. Functional is basically the amount of use a person gets out of a muscle system–it was this measure that correlated with fatigue among SLE patients.
The researchers who ran this study tried to discover factors that might contribute to muscle weakness in lupus patients. Lack of physical activity was considered to be one cause, but this did not entirely explain the differences in muscle strength between the SLE participants and the “healthy” participants. Levels of Vitamin D were also examined (Vitamin D deficiency has been linked in other studies to muscle weakness). However, there was no significant correlation discerned in this small study between Vitamin D levels and muscle strength.
The authors of this study conclude: fatigue is widely reported by women who have SLE. Muscle weakness among these women correlated to fatigue, even in the absence of disease activity. And, vitamin D levels were not found to be a significant factor in muscle weakness in the small group of SLE patients studied.