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54. Thyroid Disorders in India: Epidemiology, Pathophysiology, and Management
Authors:
1. Kutuev Zhanybek Akunovich
2. Abhay Raj Chauhan
( 1,Lecturer, Department of Surgical Diseases, Faculty of Medicine, Osh State University, Osh, Kyrgyz Republic
2,5th Year MBBS Student, Osh State University, Osh, Kyrgyz Republic)
Introduction
The thyroid gland, a small butterfly-shaped organ located in the anterior neck, plays a critical role in regulating metabolism, growth, and development. Thyroid disorders are among the most prevalent endocrine diseases globally, second only to diabetes mellitus.
In India, the burden of thyroid dysfunction is enormous — affecting nearly one in ten adults, making it a major public-health concern. The disorders range from iodine deficiency goitre and hypothyroidism to hyperthyroidism, thyroiditis, and carcinoma.
According to the Indian Council of Medical Research (ICMR) and National Health Portal (NHP), over 42 million Indians suffer from thyroid diseases, and the prevalence continues to rise with improved diagnostics and awareness.
(Source: [National Health Portal, MoHFW](https://www.nhp.gov.in/disease/endocrine/nutrition/thyroid-disorders))
2. Anatomy and Physiology Review
The thyroid gland consists of two lobes connected by an isthmus. Its secretory units, follicular cells, synthesize two major hormones:
Thyroxine (T4)
Triiodothyronine (T3)
These hormones are iodine-dependent and are regulated by the hypothalamic-pituitary-thyroid (HPT) axis through thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) feedback mechanisms.
Thyroid hormones maintain:
Basal metabolic rate (BMR)
Thermoregulation
Growth and neurodevelopment (especially in infants)
Cardiovascular and gastrointestinal function
3. Epidemiology of Thyroid Disorders in India
3.1 Prevalence and Burden
Studies from ICMR and other national surveys indicate:
Hypothyroidism: ~10.9% of the adult Indian population
Subclinical hypothyroidism: ~8–10%
Hyperthyroidism: 1.3–1.6%
Goitre (iodine deficiency): <5% in most states after universal salt iodization
Autoimmune thyroiditis: 10–12% among women of reproductive age
(Source: [ICMR-NIN Report, 2023](https://www.nin.res.in/))
3.2 Regional Variations
Before the introduction of Universal Salt Iodization (USI), endemic goitre was widespread in the Himalayan and sub-Himalayan belts — Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Bihar, and Northeast India.
Due to successful implementation of USI (1983) and later National Iodine Deficiency Disorders Control Programme (NIDDCP, 1992), the prevalence of iodine deficiency disorders (IDDs) has significantly declined.
However, non-iodine-related thyroid disorders — particularly autoimmune hypothyroidism and thyroiditis — are now the leading causes of dysfunction in urban and coastal regions.
3.3 Gender and Age Distribution
Women are affected 5–8 times more frequently than men.
Hypothyroidism is most common in middle-aged women (30–50 years).
Congenital hypothyroidism affects 1 in 2000–4000 newborns.
Subclinical hypothyroidism prevalence increases with age.
4. Classification of Thyroid Disorders
Hypofunction Primary hypothyroidism, Subclinical hypothyroidism, Congenital hypothyroidism Deficient hormone synthesis/secretion
Hyperfunction Graves’ disease, Toxic multinodular goitre, Thyroid adenoma Excessive hormone production
Inflammatory Hashimoto thyroiditis, Subacute thyroiditis, Postpartum thyroiditis Autoimmune or viral destruction
Structural Goitre, Nodular disease, Cysts, Carcinoma Altered architecture, benign or malignant
Iodine deficiency disorders (IDDs) Endemic goitre, Cretinism Insufficient iodine intake
5. Pathogenesis of Common Thyroid Disorders
5.1 Hypothyroidism
Primary (thyroidal): Autoimmune thyroiditis (Hashimoto’s), iodine deficiency, post-surgical or radioiodine therapy.
Secondary (pituitary): Low TSH due to pituitary dysfunction.
Tertiary (hypothalamic): TRH deficiency.
Autoimmune hypothyroidism involves autoantibodies against thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg), leading to follicular destruction and fibrosis.
5.2 Hyperthyroidism
Common causes include:
Graves’ disease (most common): Autoantibodies (TSI) stimulate TSH receptors.
Toxic multinodular goitre: Autonomous functioning nodules.
Toxic adenoma: Single hyperfunctioning nodule.
Pathogenesis:
TSI (thyroid-stimulating immunoglobulins) mimic TSH, activating adenyl cyclase, leading to increased thyroglobulin breakdown and hormone release.
5.3 Goitre (Iodine Deficiency Disorders)
Iodine is essential for thyroid hormone synthesis. In deficiency, TSH secretion rises, stimulating thyroid hypertrophy and hyperplasia → goitre.
Long-term deficiency in pregnancy causes cretinism in infants — with growth retardation and mental impairment.
5.4 Thyroiditis
Hashimoto’s thyroiditis: Chronic autoimmune destruction, initially hyperthyroid → hypothyroid.
Subacute granulomatous thyroiditis (De Quervain): Post-viral inflammation with painful goitre.
Postpartum thyroiditis: Autoimmune, transient, occurs within 1 year after delivery.
6. Clinical Manifestations
Hypothyroidism - Fatigue, weight gain, cold intolerance, dry skin, constipation, bradycardia, menorrhagia, slow reflexes
Hyperthyroidism -Weight loss, heat intolerance, tremors, tachycardia, anxiety, diarrhoea, lid lag, goitre
Goitre -Neck swelling, cosmetic concern, compressive symptoms (dysphagia, dyspnoea)
Thyroiditis-Painful or painless neck swelling, transient hyperthyroid symptoms
Thyroid carcinoma -Solitary hard nodule, fixation, cervical lymphadenopathy
7. Diagnosis
7.1 Laboratory Tests
1. TSH: Most sensitive screening test.
↑ in primary hypothyroidism
↓ in hyperthyroidism
2. Free T4, Free T3: Confirmatory hormone levels.
3. Autoantibodies:
Anti-TPO → Hashimoto’s
Anti-TSH receptor → Graves’
4. Thyroglobulin & Calcitonin: For carcinoma monitoring.
5. Newborn screening: TSH + T4 for congenital hypothyroidism (as part of neonatal programs in India).
7.2 Imaging
Ultrasonography: Differentiates cystic vs solid nodules, assesses size.
Radioiodine uptake scan: Distinguishes causes of hyperthyroidism.
Fine-needle aspiration cytology (FNAC): Essential for nodules and carcinoma diagnosis.
8. Management
8.1 Hypothyroidism
Drug of choice: Levothyroxine sodium
Dose: 1.6 μg/kg/day (adjust by TSH every 6–8 weeks)
Mechanism: Synthetic T4 → converted to T3 peripherally → restores euthyroid state
Lifelong therapy for autoimmune or post-surgical cases
Monitoring: Target TSH 0.5–4.5 μIU/mL
Special groups:
Pregnancy → increase dose by 30–50%
Elderly → start low, go slow
8.2 Hyperthyroidism
Antithyroid drugs (ATDs):
Carbimazole (DOC in India) → inhibits thyroid peroxidase, blocking iodination and coupling reactions.
Propylthiouracil (PTU): Also inhibits peripheral T4→T3 conversion (preferred in 1st trimester).
Beta-blockers: Propranolol for symptomatic control (tachycardia, tremor).
Radioiodine ablation (I-131): In adults not responding to ATDs.
Surgery (thyroidectomy): For large goitre, suspicion of malignancy, or pregnancy intolerance to drugs.
8.3 Thyroiditis
Subacute: NSAIDs or glucocorticoids for pain/inflammation.
Autoimmune: Monitor for hypothyroidism; treat when symptomatic.
8.4 Goitre and Iodine Deficiency
Prevention:
Use iodized salt (≥30 ppm at production, ≥15 ppm at household level)
Health education and regular monitoring under NIDDCP
Iodine supplementation for high-risk populations
(Source: [NIDDCP, MoHFW](https://main.mohfw.gov.in/organisation/national-iodine-deficiency-disorders-control-programme-niddcp))
8.5 Thyroid Cancer
Papillary & follicular: Total thyroidectomy + radioactive iodine ablation + lifelong thyroxine suppression.
Medullary: Total thyroidectomy + RET mutation screening.
Anaplastic: Poor prognosis; palliative therapy.
9. National Programs and Public Health Measures
9.1 National Iodine Deficiency Disorders Control Programme (NIDDCP)
Launch: 1992 (previously National Goitre Control Programme, 1962)
Goal: Eliminate IDDs through iodized salt use and monitoring.
Achievements: >90% of households now use iodized salt (NFHS-5, 2021).
(Source: [NFHS-5, Ministry of Health and Family Welfare](https://main.mohfw.gov.in/))
9.2 Population Screening
Many states have implemented universal thyroid screening in antenatal clinics and newborn units, improving early detection of congenital hypothyroidism and reducing developmental delay.
9.3 Awareness & Education
Public health campaigns, especially through the National Health Mission (NHM), emphasize awareness about goitre, symptoms of hypothyroidism, and the importance of iodized salt.
10. Challenges and Future Directions
Future directions include integrating digital health surveillance (similar to IHIP), improving endocrine training, and scaling up neonatal screening programs nationwide.
11. Summary (Exam-Oriented Points)
Prevalence: ~10% of Indians affected by thyroid disorders.
Most common: Hypothyroidism > Hyperthyroidism.
Major cause (historically): Iodine deficiency → now autoimmune thyroiditis predominates.
Drug of choice:
Hypothyroidism → Levothyroxine
Hyperthyroidism → Carbimazole
National programme: NIDDCP (1992)
Key prevention: Universal iodization of salt.
Complications of neglect: Infertility, miscarriage, growth retardation, cardiovascular disease.
12. Conclusion
Thyroid disorders in India have shifted from iodine deficiency to autoimmune etiologies as lifestyles and nutritional patterns evolve. Despite remarkable progress through national programs and iodized salt, millions remain undiagnosed or inadequately treated.
Early screening, patient awareness, and adherence to therapy remain the cornerstones of control.
Medical students and clinicians must recognize thyroid dysfunction as a silent epidemic and advocate for routine testing — especially in women and pregnant mothers — to ensure a healthier, iodine-sufficient India.
13. References
1. Kutuev Zh.A.Organization of stage-by-stage diagnostic and therapeutic-tactical solutions for traumatic injuries of the main vessels. Health care of Kyrgyzstan 2023, No.1, pp.172-176. https://dx.doi.org/10.51350/zdravkg2023.1.2.25.172.176
2. National Health Portal, Ministry of Health and Family Welfare. Thyroid Disorders.
[https://www.nhp.gov.in/disease/endocrine/nutrition/thyroid-disorders](https://www.nhp.gov.in/disease/endocrine/nutrition/thyroid-disorders)
3. Indian Council of Medical Research (ICMR) – National Institute of Nutrition (NIN). Iodine Deficiency Disorders and Nutrition Reports.
[https://www.nin.res.in/](https://www.nin.res.in/)
4. National Iodine Deficiency Disorders Control Programme (NIDDCP), MoHFW.
[https://main.mohfw.gov.in/organisation/national-iodine-deficiency-disorders-control-programme-niddcp](https://main.mohfw.gov.in/organisation/national-iodine-deficiency-disorders-control-programme-niddcp)
5. World Health Organization. Global Database on Iodine Deficiency.
[https://www.who.int/data/gho/data/themes/topics/iodine](https://www.who.int/data/gho/data/themes/topics/iodine)
6. NFHS-5 (2021). National Family Health Survey – India Report.
[https://main.mohfw.gov.in/](https://main.mohfw.gov.in/)
7. American Thyroid Association (ATA) Clinical Guidelines (2023 Update).
[https://www.thyroid.org/professionals/ata-professional-guidelines/](https://www.thyroid.org/professionals/ata-professional-guidelines/)
