India · Adult · Elderly · Pregnancy · Paediatric · Congenital Hypothyroidism · Thyronorm · Eltroxin · Thyrox
⚠️ Iron tablets — separate by 4 hours
⚠️ Calcium supplements — separate by 4 hours
⚠️ Antacids / sucralfate — separate by 2 hours
⚠️ PPIs (omeprazole) — may reduce absorption
⚠️ Cholestyramine — separate by 4–6 hours
✅ Take with water only, 30–60 min before breakfast
| Patient group | Starting dose | Full replacement | TSH target | Recheck TSH |
|---|---|---|---|---|
| Adult — primary hypothyroid | 50–100 mcg OD | 1.6 mcg/kg/day | 0.5–2.5 mIU/L | 6–8 weeks after dose change |
| Elderly (no cardiac disease) | 25–50 mcg OD, titrate slowly | 1.0–1.2 mcg/kg/day (lower) | 1–4 mIU/L (relaxed) | 6–8 weeks |
| Elderly with cardiac disease | 12.5–25 mcg OD | Titrate very slowly | 1–4 mIU/L | 8–12 weeks |
| Pregnancy — known hypothyroid | Increase existing dose by 25–30 mcg immediately | Full dose + 25–30 mcg | 1st trim: <2.5; 2nd/3rd: <3.0 | Every 4–6 weeks |
| Pregnancy — newly diagnosed | 100–150 mcg OD | Full weight-based dose | <2.5 mIU/L | Every 4 weeks |
| Congenital hypothyroid (neonate) | 10–15 mcg/kg/day | Full dose immediately | 0.5–2.0 mIU/L | 2 weeks, then monthly |
| Child 1–5 years | 4–6 mcg/kg/day | Full dose | 0.5–2.5 mIU/L | Every 3–6 months |
| Child 6–12 years | 3–5 mcg/kg/day | Full dose | 0.5–2.5 mIU/L | Every 6–12 months |
| Adolescent (12–18 yr) | 2–3 mcg/kg/day | Full dose | 0.5–2.5 mIU/L | Every 6–12 months |
| Post-thyroidectomy / cancer suppression | Full replacement | 1.6–2.2 mcg/kg/day | <0.1 mIU/L (low-risk: 0.1–0.5) | 6–12 months when stable |
Hypothyroidism affects an estimated 42 million people in India, making it one of the most prevalent endocrine disorders in the country. Women are disproportionately affected — approximately 1 in 10 Indian women over 35 has hypothyroidism, with significantly higher rates in areas of iodine insufficiency (certain parts of Bihar, UP, and Northeast India despite national iodisation programmes). Levothyroxine (L-T4) is the standard treatment and is available as Thyronorm, Eltroxin, and Thyrox in 25, 50, 75, 100, 125, and 150 mcg tablets across India.
Levothyroxine absorption is highly sensitive to food and co-administered substances. Taking it within 30 minutes of a meal reduces absorption by 20–40%, potentially making the difference between adequate and inadequate replacement. The tablet must be taken with a full glass of water on a completely empty stomach, at least 30 minutes before the first meal of the day. Iron tablets, calcium supplements, antacids, and sucralfate must be separated by at least 4 hours. In patients taking omeprazole or other PPIs regularly, absorption may be reduced — a higher dose or switching to liquid levothyroxine may be needed. This timing issue is the most common reason for persistently elevated TSH despite apparently adequate prescription doses.
Initiating levothyroxine in elderly patients, particularly those with ischaemic heart disease, requires a cautious approach. Abrupt full replacement can precipitate angina, arrhythmia, or acute coronary syndrome by increasing myocardial oxygen demand. Start at 12.5–25 mcg daily in patients with significant cardiac disease, increasing by 12.5–25 mcg every 6–8 weeks, guided by symptoms and TSH. The TSH target for elderly patients is more relaxed (1–4 mIU/L) — over-treatment (suppressed TSH) in the elderly causes atrial fibrillation, osteoporosis, and falls.
Thyroid hormone requirements increase by 20–30% during pregnancy, beginning as early as 4–6 weeks gestation. Untreated or undertreated hypothyroidism in pregnancy causes preeclampsia, placental abruption, preterm labour, and — critically — impaired neurological development in the fetus. Women with known hypothyroidism should increase their levothyroxine dose by 25–30 mcg immediately on confirmation of pregnancy (without waiting for TSH results). The dose increase strategy: take an extra tablet on 2 days of the week immediately (e.g. Saturday and Sunday dose doubled) — this is a practical approach for the common scenario of a known hypothyroid woman confirming pregnancy. Recheck TSH every 4 weeks throughout the first half of pregnancy.