International Journal of Preventive Medicine

: 2020  |  Volume : 11  |  Issue : 1  |  Page : 80-

Estimation of thyroid-stimulating hormone level in normal college female students in a semi-urban Indian town: Kumbakonam urban-rural epidemiological study- KURES – 7

MR Suchitra1, TS Shanthi2, Srinivasan Parthasarathy3,  
1 Department of Biochemistry and Nutrition, SASTRA Deemed to be University, Thanjavur, Tamil Nadu, India
2 Consultant Obstetrician, KRG Nursing Home, Department of Obstetrics and Gynaecology, Thanjavur, Tamil Nadu, India
3 Department of Anaesthesiology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth, Puducherry, India

Correspondence Address:
Srinivasan Parthasarathy
Department of Anesthesiology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth, Puducherry


Background: Subclinical hypothyroidism (SCH) is a biochemical disease which is characterized by elevated serum levels of thyroid stimulating hormone (TSH) with normal thyroid hormone levels. In an attempt to correct the disease at its entry point, we wished to find out the incidence of subclinical hypothyroidism in female college students in Kumbakonam, a semiurban town of India. Methods: Around 260 female college students who had no history of thyroid disease were screened for thyroid dysfunction by a TSH assay. Results: The mean age ± standard deviation was 18.72 ± 2.27 years. The mean TSH value was 3.98 mIU/mL. The incidence of abnormally high TSH values was around 11.5%. The number of such cases was 30 with low T3 values in six students. One had a value of 150 with no symptoms. Another student had a value of 0.15 and her T3-T4 profile was normal. All students were asymptomatic. None of the students had goiter.Conclusions: In an unpublished but accepted study, we found an incidence of 3.5% in the school female children in the age group of 15–17. A sudden jump in the incidence is occurring in the age group of 18–22. This needs a workup of the causative factors and their possible correction.

How to cite this article:
Suchitra M R, Shanthi T S, Parthasarathy S. Estimation of thyroid-stimulating hormone level in normal college female students in a semi-urban Indian town: Kumbakonam urban-rural epidemiological study- KURES – 7.Int J Prev Med 2020;11:80-80

How to cite this URL:
Suchitra M R, Shanthi T S, Parthasarathy S. Estimation of thyroid-stimulating hormone level in normal college female students in a semi-urban Indian town: Kumbakonam urban-rural epidemiological study- KURES – 7. Int J Prev Med [serial online] 2020 [cited 2020 Sep 19 ];11:80-80
Available from:

Full Text


Subclinical hypothyroidism (SCH) is biochemical than a clinical condition which is characterized by elevated serum levels of thyroid stimulating hormone (TSH) above the upper limit of the reference range but mostly asymptomatic with a normal concentration of thyroid hormones. It is still not clear that these clinically normal college girls will go in future to develop increased incidence of complications. As such, there are very few studies which randomly sample normal college female children in Indian semiurban population. In a study conducted among young females in south India,[1] the incidence of thyroid dysfunction is around 11.7%. There are a few studies which state that the incidence of subclinical hypothyroidism is around 4.15 to 13% in Asian pregnant population.[2],[3] Detecting subclinical thyroid dysfunction in asymptomatic teenage females may go a long way in avoiding menstrual and fertility problems later. In view of such variations and importance in preventive health, we proposed to conduct an estimation of TSH levels in normal asymptomatic female school children in Kumbakonam, a semiurban town of south India. We aimed to estimate the level of TSH in asymptomatic college female students from which to detect the incidence of students with thyroid dysfunction in them.


This prospective epidemiological observational study was conducted in a semiurban town of south India with a population of 150000 in September2019. It was done in female college students between 18–22 years of age. The institutional ethics and review board (IRBSTH 106/2019) has approved the study. The administration of the college has accepted to conduct the study. The procedure of collecting blood from students was explained to students after getting consent. TSH assay was done in all the randomly collected blood samples as a thyroid screening test. It was confirmed that no student was a known thyroid patient. All patients who received drugs for any other cause have been excluded. TSH assay was done using electrochemiluminescence immunoassay to the accuracy guidelines given by the World Health Organization (WHO) as standard.

Abnormal TSH values were grouped into two basic categories:

  • TSH elevation: TSH of more than 5 mIU/mL5 (SCH)
  • Suppressed TSH: TSH <0.4 mIU/mL
  • Others.

Any abnormal values are followed up with further tests and necessary treatment.


With a town population of 150000 and a target population of 3500 of the age group described above, the application of Qualtrix software in sample size estimation for epidemiological studies was performed. For a study to have a 90% confidence level and a margin of error 5%, a sample size of 252 was necessary. Hence a sample size of 260 was made in our study. All data were entered in an excel spreadsheet and fed into the statistics software SPSS 20.0 for descriptive statistics and confidence intervals.


All the 260 students cooperated well for the investigation. There were no dropouts which means that there was no student out of this 260 from whom the sample was not taken. No student was a known hypothyroid and on no drugs affecting the estimation. All the students belonged to the age group of 18–22. The mean TSH with the standard error was 3.98 ± 0.64 mIU/L. The variation was from 0.15 to 150. The upper and lower bound 95% confidence intervals were 5.25 and 2.73, respectively. [Table 1]. Thirty students out of 260 showed a high TSH value. This accounted for average thyroid dysfunction in the hypothyroid range to be 11.5%. The values were more than twenty in four cases. In all these cases, the T4 values were near normal. There were six cases in which the T3 were found to be lower than 100 which suggest frank hypothyroidism. All these students were also not having any major symptoms of hypothyroidism. There was only one case of a TSH value of 0.15. The student was advised to follow-up with repeat profiles and take appropriate medical advice.{Table 1}


The prevalence of asymptomatic thyroid disorders depends on various factors such as age, sex, iodine intake, and other geographical factors. The focus was on young females, as a lot of menstrual problems leading on to infertility are linked with thyroid disorders. Nair et al.[4] demonstrated that postprandial TSH levels were less than fasting values. Our samples were taken randomly. Hence, in borderline cases, we counselled for fasting profiles. Early and effective treatment of any thyroid disorder will ensure a safe obstetric journey. Hence, screening at the age of 18–21 and their correction may be useful in reducing infertility. An earlier epidemiological research work by us revealed an incidence of 3.5% of subclinical hypothyroidism with a mean TSH value was 2.99 among female school children of age 15–17. (accepted but yet to be published). In this study, the incidence has risen to around 11% in a similar population but among college students. It can be presumed that a transition phase of increased thyroid dysfunction is happening at the age of around 18–20. Rao et al.[5] in their study on adolescent females, found an incidence of 4.9% of subclinical hypothyroidism, but their age group is less than 19. Nikhita et al.[6] have found an incidence of one student among 70 young medicos which are far less than our results. As such there are very minimal data on TSH levels of college students who are not known patients of thyroid dysfunction. Only one patient in our study had a value of less than 0.4 but asymptomatic. The hormone profiles were also normal and advised for a strict follow-up. In one patient of our study, the TSH level was 150, yet did not know, she was hypothyroid. None had clinical goitre in our study. Dadia[7]et al. in their review have clearly stated that the prevalence of subclinical hypothyroidism would increase with age which goes along with our findings. Paul et al.[8] in their study have found out the incidence of subclinical hypothyroidism to be 6.5% but they have included females and males with and without goiter. We have not included goiter cases to note asymptomatic students with subclinical hypothyroidism We did not enquire the details of the dietary habits of each student, but the area of the study is a delta one.


In a sample epidemiological survey of subclinical hypothyroidism in 260 asymptomatic semi-urban school female college students of India, we found a TSH value of 3.98 ± 0.64 mIU/L. (mean with SE). Lower TSH values (<0.4) were noted only in one student. The incidence of hypothyroidism including subclinical (TSH >5) was 11.5%. We propose that a sudden transition to a higher incidence occurred in the age group of 18–21. Strong research is needed to go through the causative factors which make this happen in this age so that we can decrease the incidence of thyroid disorders in adult females.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


1Velayutham K, Selvan SS, Unnikrishnan AG. Prevalence of thyroid dysfunction among young females in a South Indian population. Indian J Endocr Metab 2015;19:781-4.
2Dhanwal DK, Bajaj S, Rajput R, Subramaniam KA, Chowdhury S, Bhandari R, et al. Prevalence of hypothyroidism in pregnancy: An epidemiological study from 11 cities in 9 states of India. Indian J Endocrinol Metab 2016;20:387-90.
3Yassaee F, Farahani M, Abadi AR. Prevalence of subclinical hypothyroidism in pregnant women in tehran-iran. Int J Fertil Steril 2014;8:163-6.
4Nair R, Mahadevan S, Muralidharan RS, Madhavan S. Does fasting or postprandial state affect thyroid function testing? Indian J Endocrinol Metab 2014;18:705-7.
5Rao PT, Subrahmanyam K, Prasad DK. Prevalence of subclinical hypothyroidism in children and adolescents of northern Andhra Pradesh population and its association with hyperlipidemia. Int J Res Med Sci 2017;5:5168-74.
6Nikhita D, Srinivasa Rao PL, Suresh V. Screening for thyroid disorders in medical undergraduate students. J Clin Sci Res 2018;7:94-6.
7Dadia B, Singh S, Gupta N. Prevalence of subclinical hypothyroidism among females with menstrual disorders. Int J Res 2019;1:630-5.
8Paul AK, Miah SR, Mamun AA, Islam S. Thyroid disorders in Khulna district: A community based study. Bangladesh Med Res Counc Bull 2006;32:66-71.