Seasonal Variations of Rheological and Hemostatic Parameters and Acute-Phase Reactants in Young, Healthy Subjects

Abstract

The incidence of cardiovascular diseases is increased in winter months. Recent studies have shown seasonal changes in plasma viscosity, fibrinogen, and factor VII activity with elevated levels during winter. An increase in these factors generates a "hypercoagulable state," which may lead to a rise in cardiovascular morbidity and mortality. It has been suggested that an increase in upper respiratory infections might be the underlying cause for the raised acute-phase reactants, in particular fibrinogen, during the winter season. We investigated seasonal variations of 26 parameters, determining blood rheology and hemostasis in 16 healthy volunteers (8 men and 8 women) aged 20 to 41 years. They were seen at monthly intervals over a period of 1 year. Seasonal variation with peak fitted values in the winter months was found for plasma viscosity (P < .001 for the seasonal difference), red blood cell deformability (P < .001), whole blood viscosity (P < .001), hemoglobin (P < .001), hematocrit (P < .001), mean corpuscular volume (P = .001), platelet count (P = .01), alpha 1-glycoprotein (P < .001), fibrinogen (measured by immunonephelometry; P < .001), plasminogen activator inhibitor-1 (P = .002), LDL cholesterol (P = .003), and triglyceride levels (P < .001). HDL cholesterol (P < .001) and cortisol (P = .001) showed inverse seasonal patterns, with a maximum during summertime. No statistically significant seasonal variations were seen for red blood cell aggregation, complement factor C4, total cholesterol, ceruloplasmin, haptoglobin, white blood cell count, and plasminogen. These data do not support the hypothesis that increased morbidity and mortality from cardiovascular diseases during winter may be mainly attributable to increased synthesis of acute-phase proteins due to infections. The cause for the seasonal variations in rheological and hemostatic parameters remains unclear and should be studied in more detail.

Determinants of inappropriate circadian blood pressure variability in children with essential hypertension

“…These findings are difficult to explain. It cannot be excluded that seasonal variations in morphological and biochemical blood parameters influenced the cited results (30,31).…”

Comparison of Selected Morphological, Rheological and Biochemical Parameters of Winter Swimmers' Blood at the End of One Winter Swimming Season and at the Beginning of Another

“…FR_HLICH et al 1997 shown seasonal changes in fibrinogen where maximum level was reached in April, and the seasonal difference was 0,32 g/L.…”

“…This phenomenon is difficult to explain. Perhaps it resulted from the fact that our winter swimmers were well-trained or have been actively involved in other sports disciplines, such as jogging, cycling, kayaking, trekking and swimming both of them may affect deformability of erythrocytes at $1.13 Pa. FR_HLICH et al (1997) indicated that RBC deformability undergoes large seasonal changes, with the peak level in November (14.5 AU) and the lowest level in April (13.1 AU) (P<001).…”

Occurrence of acute cardiovascular diseases under different atmospheric parameters

“…A legnagyobb mértékű változást a plazma fi brinogénkoncentrációja mutatja, amely alacsony légköri hőmérsékleten 23%-os emelkedéssel bír [20]. A plazmaviszkozitás maximális szintjét január hónapra teszik [21,22]. A vérnyomás szintén emelkedő értéket mutat [23,24,25].…”