Red Flags
- Myxoedema coma — hypothermia, hypotension, hypoventilation, altered mental status — IV levothyroxine plus IV hydrocortisone in ICU[1]
- Newly diagnosed hypothyroidism with concurrent unrecognised adrenal insufficiency — give hydrocortisone first to avoid precipitating adrenal crisis on starting levothyroxine[1]
- Pregnancy with overt hypothyroidism — adverse maternal/fetal outcomes; immediate levothyroxine, target TSH <2.5 in 1st trimester[1]
- Symptomatic angina or arrhythmia in elderly starting levothyroxine — start low and titrate slowly to avoid precipitating ischaemia[1]
First-line treatment
Interventions
- Subclinical hypothyroidism management[1]Treat if TSH ≥10 mIU/L, pregnancy or planning pregnancy, infertility, or symptomatic with TSH 4.5–10 plus positive anti-TPO. Otherwise observation with TSH every 6–12 months
- Iodine sufficiency check[1]Population iodisation programme has reduced iodine deficiency; residual pockets remain — check dietary iodine source where deficiency suspected
- Annual TSH monitoring once stable[1]Once euthyroid on stable LT4 dose, check TSH annually; sooner with weight change ≥10%, pregnancy, or new medications affecting absorption
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Levothyroxine (LT4)[1] | Synthetic thyroid hormone (T4) | 1.6 mcg/kg/day PO once daily on empty stomach (typically 100–125 mcg). Lower starting dose (12.5–50 mcg) in elderly, CAD, frail; titrate every 4–6 weeks | 10–15 mcg/kg/day in neonates; weight-based per age in older children | Take 30–60 minutes before food, separated from calcium, iron, PPIs by 4 hours |
| Levothyroxine in pregnancy[1] | Thyroid hormone (pregnancy adjusted) | Increase pre-pregnancy dose by 25–30% on confirmation of pregnancy; monitor TSH every 4 weeks | — | Target TSH <2.5 in 1st trimester, <3.0 thereafter |
Levothyroxine (LT4)[1]
Synthetic thyroid hormone (T4)
- Adult
- 1.6 mcg/kg/day PO once daily on empty stomach (typically 100–125 mcg). Lower starting dose (12.5–50 mcg) in elderly, CAD, frail; titrate every 4–6 weeks
- Paediatric
- 10–15 mcg/kg/day in neonates; weight-based per age in older children
Take 30–60 minutes before food, separated from calcium, iron, PPIs by 4 hours
Levothyroxine in pregnancy[1]
Thyroid hormone (pregnancy adjusted)
- Adult
- Increase pre-pregnancy dose by 25–30% on confirmation of pregnancy; monitor TSH every 4 weeks
- Paediatric
- —
Target TSH <2.5 in 1st trimester, <3.0 thereafter
Safety-net
Referral criteria
Clinical summary
Indian Thyroid Society perspective on diagnosis and treatment of hypothyroidism — TSH-driven levothyroxine titration with attention to iodine status and pregnancy.