SEASONAL-VARIATION IN THE DIAGNOSIS OF GRAVES-DISEASE

OBJECTIVE Heat intolerance is a well known symptom of Graves' disease. Therefore, it is possible that increased ambient temperature could in fluence the recognition of Graves' disease by unmasking or enhancing t he symptom of heat intolerance. Our aim was to determine if there is a seasonal variation in the diagnosis of Graves' disease. DESIGN A retr ospective study. SETTING A county hospital and clinic. PATIENTS Two hu ndred and seven patients with Graves' disease diagnosed from 1985 to 1 992. RESULTS A high correlation was found between the temperature and the number of cases of Graves' disease diagnosed. A larger proportion of patients (68%) was diagnosed during the warmer half of the year, Ma y-October, than during the cooler half. The peak incidence of the diag nosis occurred in May, when 17.4% of the patients were diagnosed. Alth ough the peak average monthly temperature occurs in July, the month of May corresponds to the time of the year when the temperature is makin g its largest positive change in the month-to-month variation. CONCLUS IONS Seasonal variations in the temperature can affect the incidence o f the diagnosis of Graves' disease. The diagnosis is more common durin g the months of higher temperature.