Investigation of thyroid hormone status among obese women of the endocrine outpatient department in a tertiary level hospital

Obesity can be defined as the excessive fat accumulation in the body beyond normal limit which enhances the probability of health impairment. WHO defines that person obese who’s BMI is equal to or more than 30kg/m2.1 It is a condition of excess body fat, is relatively random and usually based on an approximation of body fat which is called the body mass index (BMI). 2 BMI, a numerical value used to indicate the approximation of the body fat, is derived from the weight and height of an individual. It is calculated by dividing the mass in kilogram by the square of height of a person in meter unit.3,4 The exact cause of obesity is still a matter to be unearthed. However, it is evident that an imbalance in energy input and output contributes significantly for the development of obesity. When a person consumes more calories than he or she burns by exercise or physiological activities, the extra calories accumulate inside the body. And the ultimate consequence is overweight and obesity.5‒7 However, there are other factors which are directly or indirectly contribute for the development of obesity of an individual. Family studies suggest that heredity may explain up to 67% of the population variance in BMI.8,9 Obesity is associated with an increased risk of diabetes, dyslipidemia, kidney disease, cardiovascular disease, all-cause mortality and cancer.10,11 As a consequence, in developed countries, increasing rates of obesity may lead to a decline in the overall life expectancy.12 Thyroid is an endocrine gland which is located at the base of our neck. It releases hormones which controls metabolism. Two main hormones are released from thyroid glandtriidothyronine (T3) and thyroxine (T4). Thyroid gland uses iodine obtained from food to produce these two important hormones. The hypothalamus produces Thyrotropin-Releasing Hormone (TRH) that signals the pituitary to induce the thyroid gland to produce more or less of T3 and T4 by either increasing or decreasing the release of a hormone called thyroid stimulating hormone (TSH). 13‒15 It is important that the concentrations of T3 and T4 in the blood are neither too high nor too low. Depending on serum thyroid status, there are mainly three types of thyroid diseases including Hypothyroidism, Hyperthyroidism and Subclinical hypothyroidism.16 Hypothyroidism is a condition in which the body is not able to produce enough thyroid hormones, or is unable to respond or utilize existing thyroid hormones properly. Symptoms include fatigue, low energy, weight gain, bradycardia, sensitivity to cold temperatures, constipation, depressed mood or memory difficulty.17,18 Hyperthyroidism is another condition in which the body is producing too much thyroid hormone. Symptoms include difficulty sleeping (insomnia), irritability, panic attacks, weight loss despite having a good appetite, tachycardia or palpitations, sensitivity to hot temperatures, increased bowel movements or diarrhea, tremors, excess sweating and/or warm skin.19 Subclinical hypothyroidism (SCH) is defined as a serum thyroid-stimulating hormone (TSH) level above the upper limit of normal despite normal levels of serum free thyroxine.20 Obesity and thyroid dysfunction are common diseases. Hypothyroidism has often thought to be the cause of obesity. In recentyears, there has been an increasing attention to thyroid function in obese patients.21‒23 But the prevalence of hypothyroidism among obese women is not known in our country. The finding of the study might give the clinicians an idea regarding the investigation of thyroid hormone status in obese women and consequently they will be particularly alert for the screening their thyroid dysfunction.