Circadian Rhythm of Oral Temperature in Adult Hyperthyroids, Sudan

Introduction: A 24 hours long cyclic change in body temperature, ie. body temperature circadian rhythm is used as a marker of other body circadian rhythms.

Objectives: To determine circadian rhythm in oral temperature of adult hyperthyroids at Nyala and Alfashir- western cities, Sudan.

Study Design: A descriptive cross-sectional of stratified random sampling.

Place and Duration of Study: Department of Physiology, Faculty of Medicine, Gezira University, Wadmadani, Sudan, from December 2006 to March 2007.

Methodology: A sample of thirty clinically diagnosed thyrotoxic cases (females = 29, and a male) of age ranging from 18 to 50 years, attended to Sudanese atomic energy corporation (SAEC) for receiving positively confirmed laboratory tests were enrolled to conduct this study. Early morning and late evening oral temperatures were recorded by the mercury-in-glass thermometer. A questionnaire was used to exclude any other fever conditions. Thyroid hormones, ie. T3, T4, and TSH levels were measured by radioimmunoassay (RIA) at SAEC of Nyala with reference ranges 0.4 - 4.4 mIU/L, 0.69 - 2.02 nmol/L, and 50 - 150 nmol/L for TSH, T3, and T4 respectively. Subjects of T3 and T4 values above reference ranges with TSH below reference were considered hyperthyroid. The obtained data were analyzed statistically by the statistical package for the social science programme (SPSS), ie. T-test.

Results: Mean oral temperature and circadian rhythm were found to be 37.25 ± 0.34ºC and 0.43 ± 0.30ºC respectively. The effect of sex on mean oral temperature was statistically significant (p = 0.01), whereas age did not show any statistical effect (p = 0.36).

Conclusion: The decreased oral temperature circadian rhythm of thyrotoxic patients, confirms that other body functions also abnormally affected when body temperature circadian rhythm is abnormal.