A condition called lymphopenia – low levels of lymphocyte blood cells – could be an early warning for illness, a new study suggests.
Danish researchers linked the condition to a 60% increased risk of death from any cause during the study period.
Falling lymphocyte levels
A low lymphocyte count was also associated with a 1.5- to 2.8-fold increased risk of death from cancer, heart disease, respiratory disease, infections and other causes.
The findings come from an analysis of data from more than 108 000 people in Denmark, aged 20 to 100, between 2003 and 2015.
Older age was associated with falling lymphocyte levels, the study authors said in the report published in the CMAJ (Canadian Medical Association Journal).
The researchers suggested that the link between lymphopenia and death risk may stem from a reduced ability of the immune system to fight serious diseases.
Lymphopenia could also be an indication of frailty, which increases the risk of illness and death, the study authors noted.
"Our study showed that participants with lymphopenia were at high risk of dying from any cause, regardless of any other risk factor for all-cause mortality including age," according to Dr Stig Bojesen and colleagues. Bojesen is a clinical professor at Herlev-Gentofte Hospital in Herlev, Denmark.
Lymphopenia is often detected during routine blood tests, but patients typically aren't referred for follow-up because its usefulness as a predictor of future health wasn't known, the authors said in a journal news release.
The new findings may help doctors identify at-risk people, the team added.
"Using the absolute two-year risks of all-cause mortality, physicians can identify high-risk individuals with lymphopenia (e.g., smokers older than 80 years) who might benefit from additional surveillance," Bojesen and colleagues concluded.
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