The thyroid gland is one of the most important endocrine organs in the human body and plays a crucial role in maintaining normal growth, development, metabolism, thermogenesis, and reproductive functions. It synthesizes and secretes the hormones thyroxine (T4) and triiodothyronine (T3), which regulate cellular metabolism and influence the function of nearly every organ system. The secretion of these hormones is regulated by thyroid-stimulating hormone (TSH) through the hypothalamic-pituitary-thyroid axis, maintaining physiological homeostasis within the body (1). Thyroid dysfunction refers to a disturbance in the normal synthesis, secretion, or action of thyroid hormones, resulting in either hypothyroidism or hyperthyroidism. Hypothyroidism is characterized by deficient thyroid hormone production leading to reduced metabolic activity, whereas hyperthyroidism results from excessive thyroid hormone secretion causing increased metabolic functions (2). In addition to overt disease, subclinical hypothyroidism and subclinical hyperthyroidism are increasingly recognized due to improved biochemical diagnostic methods. These conditions are characterized by abnormal serum TSH levels with normal circulating thyroid hormone concentrations and may progress to overt thyroid disease if left untreated (3). Thyroid disorders are among the most common endocrine diseases worldwide and represent a significant public health concern in India. It has been estimated that nearly 42 million people in India suffer from various thyroid disorders, making it one of the most prevalent endocrine conditions in the country (4). Although iodine deficiency disorders have declined considerably following the implementation of universal salt iodization programs, thyroid dysfunction continues to affect a large segment of the Indian population (5). Women are particularly susceptible to thyroid disorders due to hormonal fluctuations, autoimmune predisposition, genetic susceptibility, and reproductive factors. The prevalence of thyroid dysfunction is reported to be five to ten times higher in women than in men (6). Young women constitute a vulnerable population because thyroid hormones play an essential role in reproductive health, menstrual function, fertility, and pregnancy outcomes. Even minor alterations in thyroid hormone levels may adversely affect reproductive physiology and overall health status (7). India has witnessed a rising prevalence of thyroid dysfunction over the past two decades. A landmark multicentric epidemiological study conducted by Unnikrishnan et al. across eight major Indian cities reported that the prevalence of hypothyroidism among Indian adults was 10.95%, while subclinical hypothyroidism was present in approximately 8.02% of the population (8). The study further demonstrated that women were disproportionately affected compared with men. Similarly, Kochupillai reported that thyroid disorders constitute a major endocrine burden in India and emphasized the need for early detection and management strategies (9). Young women are particularly affected by thyroid dysfunction because of the intricate relationship between thyroid hormones and reproductive endocrinology. Thyroid hormones influence gonadotropin secretion, ovarian function, follicular development, ovulation, and endometrial receptivity. Hypothyroidism has been associated with menstrual disturbances such as oligomenorrhea, menorrhagia, polymenorrhea, and amenorrhea, whereas hyperthyroidism may result in oligomenorrhea, hypomenorrhea, and menstrual irregularities (9). Furthermore, thyroid dysfunction is recognized as an important cause of infertility, recurrent pregnancy loss, and adverse obstetric outcomes among Indian women (10). The clinical manifestations of thyroid dysfunction are often nonspecific and vary depending on the severity and duration of hormonal imbalance. Patients with hypothyroidism commonly present with fatigue, lethargy, weight gain, cold intolerance, constipation, dry skin, hair loss, depression, and impaired cognitive function. Hyperthyroidism, on the other hand, is characterized by symptoms such as weight loss, heat intolerance, palpitations, excessive sweating, anxiety, tremors, and nervousness (11). Because these symptoms overlap with many common medical and psychological conditions, thyroid dysfunction often remains undiagnosed for prolonged periods. Several Indian studies have highlighted the substantial burden of undiagnosed thyroid disease among women of reproductive age. Marwaha et al. reported a significant prevalence of thyroid dysfunction among apparently healthy Indian adults and observed that subclinical hypothyroidism was the most common abnormality detected during screening (12). Similar findings were reported by Sahay and Nagesh, who emphasized that hypothyroidism remains one of the most underdiagnosed endocrine disorders in India despite the availability of reliable diagnostic facilities (13). In addition to reproductive consequences, thyroid dysfunction contributes to a variety of metabolic and cardiovascular complications. Untreated hypothyroidism has been associated with obesity, dyslipidemia, hypertension, atherosclerosis, and increased cardiovascular risk. Hyperthyroidism may lead to cardiac arrhythmias, osteoporosis, muscle wasting, and neuropsychiatric disorders (14). Early diagnosis and treatment are therefore essential to prevent long-term morbidity and improve quality of life. Biochemical assessment remains the cornerstone for diagnosing thyroid disorders. Serum TSH measurement is considered the most sensitive screening test for thyroid dysfunction and is widely used in clinical practice. Elevated TSH levels typically indicate primary hypothyroidism, whereas suppressed TSH levels suggest hyperthyroidism. Measurement of free thyroxine (FT4) and free triiodothyronine (FT3) helps differentiate overt disease from subclinical conditions and provides information regarding disease severity (15). Recent advances in immunoassay techniques have significantly improved the accuracy and reliability of thyroid function testing, facilitating earlier detection of thyroid abnormalities. The increasing prevalence of thyroid disorders among young Indian women may be attributed to several factors, including autoimmune thyroiditis, nutritional deficiencies, environmental influences, genetic predisposition, obesity, stress, and changing lifestyle patterns (16). Urbanization, sedentary behavior, and dietary transitions have further contributed to the growing burden of endocrine disorders in India. Despite these concerns, awareness regarding thyroid disease remains inadequate among the general population, resulting in delayed diagnosis and treatment. Considering the high prevalence of thyroid dysfunction among women, its profound impact on reproductive and metabolic health, and the availability of simple biochemical diagnostic tests, early detection through clinical and laboratory evaluation is essential. Young women presenting with menstrual disturbances, unexplained weight changes, fatigue, infertility, or other suggestive symptoms should undergo thyroid function assessment to facilitate timely diagnosis and intervention.

Study Design The present study was designed as a hospital-based cross-sectional observational study conducted to evaluate the clinical manifestations and biochemical profile of thyroid dysfunction among young women attending a tertiary care teaching hospital. Study Setting The study was carried out in the Department of Biochemistry at a tertiary care teaching hospital in India. The study included patients attending the outpatient and inpatient departments during the study period. Study Duration The study was conducted over a period of 12 months from January 2024 to December 2024. Study Population The study population comprised young women aged 18–35 years who attended the hospital with symptoms suggestive of thyroid dysfunction or who were referred for thyroid function testing. Sample Size A total of 150 young women were enrolled in the study. The sample size was determined based on previous Indian studies reporting the prevalence of thyroid dysfunction among women of reproductive age. Considering a prevalence of approximately 11%, a confidence level of 95%, and an allowable error of 5%, the minimum sample size was calculated. To improve statistical validity and compensate for possible dropouts, 150 participants were included. Sampling Technique Participants were selected using a consecutive sampling method. All eligible patients fulfilling the inclusion criteria during the study period were recruited until the required sample size was achieved. Ethical Considerations The study protocol was reviewed and approved by the Institutional Ethics Committee (IEC) prior to commencement of the study. Written informed consent was obtained from all participants. Confidentiality of patient information was maintained throughout the study. The study was conducted according to the ethical principles outlined in the Declaration of Helsinki. Inclusion Criteria The following participants were included in the study: 1. Females aged between 18 and 35 years. 2. Patients willing to participate in the study. 3. Patients providing written informed consent. 4. Patients presenting with symptoms suggestive of thyroid dysfunction such as: Fatigue, Weight gain or weight loss, Menstrual irregularities, Hair fall, Palpitations, Heat or cold intolerance, Neck swelling, Constipation, Anxiety or nervousness Exclusion Criteria The following patients were excluded: 1. Known cases of thyroid disease already receiving treatment. 2. Pregnant women. 3. Women with severe systemic illnesses. 4. Patients receiving medications affecting thyroid function such as: Amiodarone, Lithium, Glucocorticoids, Antithyroid drugs 5. Patients with chronic renal disease. 6. Patients with chronic liver disease. 7. Patients unwilling to participate. Data Collection Procedure After obtaining informed consent, each participant underwent detailed clinical evaluation and biochemical assessment. Statistical Analysis Data were entered into Microsoft Excel and analyzed using Statistical Package for Social Sciences (SPSS) version 25.0.

Table 1: Age Distribution of Study Participants (n = 150) Age Group (Years) Number of Participants (n) Percentage (%) 18–22 45 30 23–27 52 34.7 28–31 31 20.7 32–35 22 14.6 Total 150 100 Mean Age: 25.8 ± 4.7 years Median Age: 25 years Age Range: 18–35 years Table 1 shows the age-wise distribution of the 150 young women included in the study. The participants were categorized into four age groups ranging from 18 to 35 years. A total of 150 young women aged 18–35 years were included in the study. The mean age of the participants was 25.8 ± 4.7 years. The majority of participants belonged to the 23–27 years age group (34.7%), followed by the 18–22 years age group (30.0%). Women aged 28–31 years and 32–35 years constituted 20.7% and 14.6% of the study population, respectively. The findings indicate that most participants were in the active reproductive age group. Table 2: Prevalence of Thyroid Dysfunction among Study Participants (n = 150) Thyroid Status Number of Participants (n) Percentage (%) Euthyroid 102 68 Subclinical Hypothyroidism 27 18 Overt Hypothyroidism 14 9.3 Subclinical Hyperthyroidism 3 2 Overt Hyperthyroidism 4 2.7 Total 150 100 Table 2 depicts the distribution of thyroid function status among the 150 young women included in the study. Based on biochemical assessment of serum TSH, FT3, and FT4 levels, participants were categorized as euthyroid, subclinical hypothyroid, overt hypothyroid, subclinical hyperthyroid, or overt hyperthyroid. A total of 150 young women were evaluated for thyroid dysfunction. Among them, 102 participants (68.0%) were euthyroid, while 48 participants (32.0%) exhibited thyroid dysfunction. Subclinical hypothyroidism was the most prevalent thyroid disorder, affecting 27 participants (18.0%), followed by overt hypothyroidism in 14 participants (9.3%). Overt hyperthyroidism and subclinical hyperthyroidism were observed in 4 (2.7%) and 3 (2.0%) participants, respectively. Overall, hypothyroid disorders accounted for 27.3% of the study population, whereas hyperthyroid disorders accounted for 4.7%. These findings suggest that hypothyroidism, particularly its subclinical form, is the predominant thyroid abnormality among young women. Table 3: Distribution of Clinical Manifestations among Participants with Thyroid Dysfunction (n = 48) Clinical Manifestation Number of Participants (n) Percentage (%) Fatigue / Easy Tiredness 33 68.7 Weight Gain 26 54.2 Menstrual Irregularities 21 43.8 Hair Loss 19 39.6 Constipation 15 31.2 Cold Intolerance 14 29.1 Anxiety / Nervousness 10 20.8 Palpitations 8 16.7 Heat Intolerance 6 12.5 Tremors 4 8.3 Neck Swelling (Goiter) 3 6.2 Table 3 illustrates the frequency and distribution of clinical manifestations among the 48 participants diagnosed with thyroid dysfunction. The symptoms varied in severity and presentation depending on the type and duration of thyroid disorder. Most participants presented with more than one symptom at the time of evaluation. Among the 48 participants diagnosed with thyroid dysfunction, fatigue was the most common clinical manifestation, reported by 33 participants (68.7%), followed by weight gain in 26 participants (54.2%) and menstrual irregularities in 21 participants (43.8%). Hair loss was observed in 39.6% of cases, while constipation and cold intolerance were present in 31.2% and 29.1%, respectively. Hyperthyroid-related symptoms such as anxiety, palpitations, heat intolerance, and tremors were observed less frequently. Neck swelling was identified in 6.2% of participants. These findings indicate that hypothyroid symptoms predominated among the study population. Table 4: Comparison of Biochemical Profile between Euthyroid and Thyroid Dysfunction Groups Biochemical Parameter Euthyroid Group (n = 102) Mean ± SD Thyroid Dysfunction Group (n = 48) Mean ± SD p-value TSH (mIU/L) 2.45 ± 1.02 8.62 ± 4.51 <0.001* FT3 (pg/mL) 3.41 ± 0.56 2.62 ± 0.81 <0.001* FT4 (ng/dL) 1.24 ± 0.28 0.82 ± 0.35 <0.001* Statistically significant (p < 0.05 Table 4 presents the comparison of thyroid function parameters between euthyroid participants and participants diagnosed with thyroid dysfunction. Serum Thyroid Stimulating Hormone (TSH), Free Triiodothyronine (FT3), and Free Thyroxine (FT4) levels The biochemical profile of the study participants is shown in Table 4. The mean serum TSH level was significantly higher among participants with thyroid dysfunction (8.62 ± 4.51 mIU/L) compared to euthyroid participants (2.45 ± 1.02 mIU/L) (p < 0.001). Conversely, mean FT3 and FT4 levels were significantly lower in the thyroid dysfunction group (2.62 ± 0.81 pg/mL and 0.82 ± 0.35 ng/dL, respectively) compared with the euthyroid group (3.41 ± 0.56 pg/mL and 1.24 ± 0.28 ng/dL, respectively). The differences observed for all biochemical parameters were statistically highly significant, confirming the presence of thyroid hormone imbalance among affected participants. Table 5 illustrates the distribution of menstrual abnormalities among the 48 participants diagnosed with thyroid dysfunction. Thyroid hormones play a vital role in maintaining normal reproductive function by regulating the hypothalamic-pituitary-ovarian axis. Consequently, disturbances in thyroid hormone levels can significantly affect menstrual regularity and reproductive health. Table 5: Menstrual Abnormalities among Participants with Thyroid Dysfunction (n = 48) Menstrual Abnormality Number of Participants (n) Percentage (%) Oligomenorrhea 10 20.8 Menorrhagia 6 12.5 Irregular Menstrual Cycles 5 10.4 Amenorrhea 2 4.2 Normal Menstrual Pattern 25 52.1 Total 48 100 Among the 48 participants with thyroid dysfunction, 23 women (47.9%) had menstrual abnormalities. Oligomenorrhea was the most frequent abnormality, observed in 10 participants (20.8%), followed by menorrhagia in 6 participants (12.5%), irregular menstrual cycles in 5 participants (10.4%), and amenorrhea in 2 participants (4.2%). The remaining 25 participants (52.1%) had normal menstrual cycles. These findings suggest a strong association between thyroid dysfunction and menstrual disturbances in young women.

The present study entitled “Clinical and Biochemical Evaluation of Thyroid Dysfunction in Young Women” was undertaken to assess the prevalence of thyroid dysfunction and its clinical and biochemical correlation among young women aged 18–35 years attending a tertiary care hospital. Thyroid disorders are increasingly recognized as a significant public health concern in India, particularly among women of reproductive age due to their close association with metabolic and reproductive functions. In the present study, the prevalence of thyroid dysfunction was found to be 32%, with subclinical hypothyroidism (18%) being the most common abnormality followed by overt hypothyroidism (9.3%). Hyperthyroid conditions were comparatively less frequent. These findings are consistent with the epidemiological study conducted by Unnikrishnan et al., who reported a prevalence of hypothyroidism of 10.95% in Indian adults, with a higher burden among women and a significant proportion of subclinical cases (3). The higher prevalence in the present study may be attributed to hospital-based sampling, where symptomatic individuals are more likely to be included. The predominance of hypothyroidism over hyperthyroidism observed in this study aligns with Indian literature, which consistently reports hypothyroidism as the most common thyroid disorder. Sahay and Nagesh emphasized that hypothyroidism is a major endocrine disorder in India and often remains underdiagnosed due to nonspecific clinical presentation (2). The high burden of subclinical hypothyroidism in young women is clinically significant as it may progress to overt disease if not detected and managed early. In the present study, the most common clinical manifestations among thyroid dysfunction cases were fatigue (68.7%), weight gain (54.2%), menstrual irregularities (43.8%), and hair loss (39.6%). These findings are in agreement with Marwaha et al., who reported that hypothyroid patients frequently present with nonspecific symptoms such as fatigue, weight gain, and menstrual disturbances in the Indian population (7). Similarly, Sharma et al. observed that menstrual irregularities were significantly associated with thyroid dysfunction among reproductive-age women (9). Menstrual disturbances were observed in nearly half of the affected participants in the present study (47.9%). The most common abnormality was oligomenorrhea followed by menorrhagia. Thyroid hormones influence reproductive physiology through regulation of the hypothalamic–pituitary–ovarian axis. Hypothyroidism is known to increase thyrotropin-releasing hormone (TRH), which in turn elevates prolactin levels, leading to anovulation and menstrual disturbances. These findings are consistent with Ajmani et al., who reported a strong association between thyroid dysfunction and menstrual irregularities in Indian women (10). Biochemical evaluation in the present study showed significantly elevated serum TSH levels and reduced FT3 and FT4 levels among participants with thyroid dysfunction compared to euthyroid individuals (p < 0.001). This biochemical pattern is characteristic of primary hypothyroidism. Similar observations were reported by Marwaha et al., who demonstrated that elevated TSH is the most sensitive marker for detecting early thyroid dysfunction in Indian adults (7). The reliability of TSH as a screening tool has also been emphasized in clinical guidelines by the Indian Thyroid Society. The high prevalence of thyroid dysfunction among young women in the present study may be attributed to multiple factors. India is known to have a significant burden of autoimmune thyroiditis, which is one of the leading causes of hypothyroidism in iodine-sufficient regions. Other contributing factors include genetic predisposition, dietary habits, environmental pollutants, obesity, stress, and micronutrient deficiencies such as iron and selenium deficiency (6). Urbanization and lifestyle changes have further contributed to the increasing incidence of endocrine disorders in younger populations. Another important observation in this study was the high proportion of subclinical hypothyroidism (18%). Subclinical thyroid dysfunction is often asymptomatic and detected only through biochemical screening. However, it carries clinical significance as it may progress to overt hypothyroidism and is associated with adverse metabolic and reproductive outcomes. Unnikrishnan et al. also highlighted the importance of identifying subclinical cases in the Indian population due to their high prevalence and potential progression (3). The present study also demonstrated a strong association between thyroid dysfunction and reproductive health disturbances. Nearly half of the affected participants had menstrual abnormalities, highlighting the critical role of thyroid hormones in female reproductive physiology. This is supported by Sahay et al., who reported that thyroid disorders are a common and often overlooked cause of infertility and menstrual irregularities in Indian women (2). The clinical overlap of thyroid dysfunction symptoms with common conditions such as stress, anemia, and lifestyle-related fatigue often leads to delayed diagnosis. Therefore, a high index of suspicion is required, especially in young women presenting with nonspecific symptoms. Routine thyroid screening in high-risk groups may facilitate early diagnosis and prevent long-term complications such as infertility, dyslipidemia, cardiovascular disease, and metabolic syndrome. The strength of the present study lies in the combined clinical and biochemical evaluation of thyroid dysfunction in a defined age group of young women. However, the study also has certain limitations, including its hospital-based design, relatively small sample size, and lack of long-term follow-up to assess progression of subclinical disease. Despite these limitations, the findings of the present study emphasize the need for increased awareness and early screening of thyroid disorders among young Indian women. Early detection through simple biochemical tests such as serum TSH can significantly improve clinical outcomes and quality of life. In conclusion, thyroid dysfunction is highly prevalent among young women, with hypothyroidism being the predominant abnormality. The study highlights the importance of correlating clinical symptoms with biochemical parameters for accurate diagnosis. Early identification and appropriate management are essential to reduce the burden of thyroid-related morbidity in the Indian population.

Thyroid dysfunction is a significant health problem among young women, with subclinical hypothyroidism being the most common disorder. Clinical symptoms such as fatigue, weight gain, menstrual irregularities, and hair loss should prompt biochemical evaluation. Routine screening using serum TSH, FT3, and FT4 can facilitate early diagnosis and treatment. Increased awareness, regular health check-ups, and timely intervention are essential to reduce the burden of thyroid-related morbidity among young Indian women.

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