By Todd Neale, Staff Writer, MedPage Today April 28, 2010 Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
PRAGUE — Among patients who have suffered a traumatic brain injury, vitamin D deficiency is associated with an increased likelihood of having chronic fatigue, Dutch researchers found.
Of 90 such patients, 80% who were fatigued had the vitamin deficiency, compared with 40% of those who were not fatigued (P<0.05), Jessica Schnieders, MD, of Rijnstate Hospital in Arnhem, the Netherlands, reported at the European Congress of Endocrinology in Prague.
Having a sleep disorder strengthened the association between vitamin D deficiency — defined as a level less than 50 nmol/L — and fatigue, Schnieders said in an interview.
“I think it’s important to get knowledge to the patients, the rehabilitation doctors, and the family doctors that they should look at vitamin D and sleep in these patients,” she said.
Schnieders said all of the patients who had a vitamin D deficiency were treated, and many said they felt better.
Although the study could not establish a causal relationship between low vitamin D levels and fatigue, treating the vitamin deficiency can benefit other areas, including bone health, she said.
Previous studies have shown that some patients with a traumatic brain injury have hormone deficiencies related to damage to the pituitary gland. Schnieders and her colleagues wanted to find out whether this, as well as other factors like vitamin D deficiency, might explain the fatigue commonly seen after traumatic brain injury.
The researchers randomly selected 100 former patients of their rehabilitation center to participate in the study, and 90 agreed (26 females and 64 males). It had been about 10 years since the traumatic brain injuries.
All filled out a fatigue questionnaire and provided information on emotional well-being, quality of life, attention, coping style, daily activity, and physical performance as assessed on a cycling test. The researchers also measured vitamin D levels.
Slightly more than half (51%) of the patients reported being severely fatigued. As expected, these patients had more anxiety and a lower quality of life.
Deficiency in at least one of the pituitary hormones was identified in 29%, growth hormone deficiency was found in 24%, and gonadal hormone deficiency was observed in 10%. None of these deficiencies was significantly related to fatigue.
In a multivariate analysis including hormone deficiencies, vitamin D deficiency, sleep problems, attention, body mass index, and gender, vitamin D deficiency was the only factor independently associated with fatigue (P<0.05).
It is unclear why sleep problems strengthened the negative effect of vitamin D deficiency on fatigue, but Schnieders said there is some evidence linking melatonin, which is involved in regulating circadian rhythms, and vitamin D.
The observational study could not prove that vitamin D deficiency was causing the fatigue.
Schnieders said another possible explanation for the findings could be that fatigued patients are more likely to remain inside and not get enough exposure to sunlight.
“But I think it has something to do with the immunological system because both sleep and vitamin D are involved in the immunological system,” she said.
Schnieders reported no conflicts of interest.