Hypothyroidism

Also known as: Underactive Thyroid, Low Thyroid, Hashimotos Thyroiditis

Note: This article gives a general overview of the condition. Symptoms and treatment depend on individual medical history, so use this as background reading before discussing with your physician.
ICD-10E03
Prevalence (India)10.9 crore Indians affected, women 3x more than men

Quick facts

  • Primary test: TSH (with Free T4 if abnormal)
  • Standard treatment: Levothyroxine
  • Most common cause: Hashimoto thyroiditis (autoimmune)
  • Lifelong treatment for most patients

Hypothyroidism is an underactive thyroid gland that does not produce enough thyroid hormone. It affects millions of Indians, with women three times more likely to develop it than men.

Symptoms

Fatigue, weight gain, cold intolerance, dry skin, hair loss, constipation, depression, and slow heart rate. Many symptoms are subtle and often dismissed as aging or stress.

Causes

The most common cause globally is Hashimoto thyroiditis, an autoimmune condition where the immune system attacks the thyroid. Iodine deficiency was common historically but is now rare in India due to iodized salt.

Diagnosis and monitoring

A TSH test is the primary diagnostic tool. A TSH above 4.0 mIU/L with low Free T4 confirms overt hypothyroidism. Subclinical hypothyroidism (TSH 4-10 with normal T4) is common and may or may not require treatment depending on symptoms and other factors.

Treatment

Levothyroxine is the standard treatment, taken daily on empty stomach. Dose is titrated based on TSH levels, with testing every 6-8 weeks after adjustments. Most patients require lifelong treatment.

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Written by

Dr. Selva Bharti

MD Medicine, DM Cardiology · Medical Reviewer, Endocrinology and Internal Medicine

Dr. Selva Bharti is an internal medicine physician with specialized training in cardiology and endocrinology, reviewing diabetes, thyroid, PCOS, and cardiovascular content on MasterDoctor.

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Medically reviewed by · April 24, 2026

Dr. Rahul Tripathi

PhD Pharmaceutical Sciences · Pharmaceutical Reviewer

Dr. Rahul Tripathi is a pharmaceutical sciences PhD with 14+ years in drug development and clinical pharmacology, reviewing all medication-related content.

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