Thyroid Hormone Pregnancy: A

Levothyroxine (Elderly)

Brand names: Eltroxin, Euthyrox

Adult dose

Dose: 25–50 micrograms once daily initially (elderly); titrate every 6–8 weeks; target TSH 2–4 mU/L in elderly

Route: oral

Frequency: once daily (30 min before breakfast, consistent timing)

Max: Titrated to TSH

Elderly: start low (25 mcg), go slow — cardiac risk; target TSH 2–4 mU/L (not 0.5–2 as in young); avoid over-treatment

Dose: 10 micrograms/kg

Route: oral

Frequency: once daily

Max: 200 micrograms/day (adolescent)

Concentration: Liquid: 25 micrograms/5 mL micrograms/ml

Congenital hypothyroidism: 10–15 mcg/kg/day; titrate to normalise TSH; liquid formulation for infants — must not be crushed

Renal

No dose adjustment required

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Patient weight (kg)

Congenital hypothyroidism: 10–15 mcg/kg/day; titrate to normalise TSH; liquid formulation for infants — must not be crushed

Cardiac risk of over-treatment: AF, angina — target higher TSH in elderly (2–4 mU/L vs. 0.5–2 in young)
Absorption: take consistently 30–60 min before breakfast; levothyroxine is a narrow therapeutic index drug
Wockhardt brand change: in 2022, NHS England issued guidance on brand-switching — check brand consistency

Reference: BNFc; BNF 86; BTA/NICE guidelines; RCP guidance 2019. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways