Seasonal variation in serum cholesterol levels: treatment implications and possible mechanisms

UMMS Affiliation

Department of Medicine, Division of Cardiovascular Medicine; Department of Medicine, Division of Preventive and Behavioral Medicine

Publication Date


Document Type



Adult; Cholesterol; Cholesterol, HDL; Cholesterol, LDL; Female; Hemodilution; Humans; Hypercholesterolemia; Longitudinal Studies; Male; Middle Aged; *Periodicity; *Seasons; Triglycerides; United States


Behavioral Disciplines and Activities | Community Health and Preventive Medicine | Preventive Medicine


BACKGROUND: A variety of studies have noted seasonal variation in blood lipid levels. Although the mechanism for this phenomenon is not clear, such variation could result in larger numbers of people being diagnosed as having hypercholesterolemia during the winter.

METHODS: We conducted a longitudinal study of seasonal variation in lipid levels in 517 healthy volunteers from a health maintenance organization serving central Massachusetts. Data collected during a 12-month period for each individual included baseline demographics and quarterly anthropometric, blood lipid, dietary, physical activity, light exposure, and behavioral information. Data were analyzed using sinusoidal regression modeling techniques.

RESULTS: The average total cholesterol level was 222 mg/dL (5.75 mmol/L) in men and 213 mg/dL (5.52 mmol/L) in women. Amplitude of seasonal variation was 3.9 mg/dL (0.10 mmol/L) in men, with a peak in December, and 5.4 mg/dL (0.14 mmol/L) in women, with a peak in January. Seasonal amplitude was greater in hypercholesterolemic participants. Seasonal changes in plasma volume explained a substantial proportion of the observed variation. Overall, 22% more participants had total cholesterol levels of 240 mg/dL or greater (> or =6.22 mmol/L) in the winter than in the summer.

CONCLUSIONS: This study confirms seasonal variation in blood lipid levels and suggests greater amplitude in seasonal variability in women and hypercholesterolemic individuals, with changes in plasma volume accounting for much of the variation. A relative plasma hypervolemia during the summer seems to be linked to increases in temperature and/or physical activity. These findings have implications for lipid screening guidelines. Further research is needed to better understand the effects of a relative winter hemoconcentration.

DOI of Published Version



Arch Intern Med. 2004 Apr 26;164(8):863-70. Link to article on publisher's site

Journal/Book/Conference Title

Archives of internal medicine 15596653 15596654

Related Resources

Link to article in PubMed

PubMed ID