The absorption after oral administration is variable and incomplete: 50-80%, particularly in the presence of food. The intravenous dose is therefore lower.
dose recommendation of formulary compared to licensed use (on-label versus off-label)
No information is present at this moment.
Available formulations
No information is present at this moment.
Dosages
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Hypothyroidism
Oral
0 months
up to
6 months
6
- 10
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same wayevery day.
The dose should then be titrated based on the TSH level (aiming for low normal) and FT4 level (aiming for high normal) If the hypothyroidism lasts longer, the starting dose should be lower than the desired maintenance dose (50%) in order to avoid side effects
6 months
up to
1 year
5
- 8
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day.
The dose should then be titrated based on the TSH level (aiming for low normal) and FT4 level (aiming for high normal) If the hypothyroidism lasts longer, the starting dose should be lower than the desired maintenance dose (50%) in order to avoid side effects
1 year
up to
5 years
4
- 6
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day.
The dose should then be titrated based on the TSH level (aiming for low normal) and FT4 level (aiming for high normal) If the hypothyroidism lasts longer, the starting dose should be lower than the desired maintenance dose (50%) in order to avoid side effects
5 years
up to
12 years
3
- 5
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day.
The dose should then be titrated based on the TSH level (aiming for low normal) and FT4 level (aiming for high normal) If the hypothyroidism lasts longer, the starting dose should be lower than the desired maintenance dose (50%) in order to avoid side effects
12 years
up to
18 years
2
- 3
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day.
The dose should then be titrated based on the TSH level (aiming for low normal) and FT4 level (aiming for high normal) If the hypothyroidism lasts longer, the starting dose should be lower than the desired maintenance dose (50%) in order to avoid side effects
Intravenous
1 month
up to
18 years
If not absorbed orally. The IV dose is derived from the oral dose in consultation with a paediatrician-endocrinologist. The intravenous dose is lower than the oral dose, due to the varying and incomplete absorption after oral administration.
Congenital hypothyroidism
Oral
0 years
up to
1 year
Initial dose:
10
microg./kg/day
in 1
dose Induction phase in order to achieve normalization of FT4 and TSH. In severe hypothyroidism (FT4 < 8 pmol/l), the initial dose is repeated after 12 hours as a one-off..
Maintenance dose:
5
- 8
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day.
The dose adjustment is about 1 mcg/kg/day, rounded off to the nearest unit of ± 6.25 mcg (a quarter of a tablet of 25 mcg). The dosage should then be titrated based on the TSH and FT4 values.
Target values: Induction phase: FT4 25-35 pmol/l; TSH 0.4-4.0 Maintenance: FT4: in the reference range, TSH 0.4-4.0
1 year
up to
5 years
Initial dose:
10
microg./kg/day
in 1
dose Induction phase in order to achieve normalization of FT4 and TSH. In severe hypothyroidism (FT4 < 8 pmol/l), the initial dose is repeated after 12 hours as a one-off..
Maintenance dose:
5
- 6
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day
The dose adjustment is about 1 mcg/kg/day, rounded off to the nearest unit of ± 6.25 mcg (a quarter of a tablet of 25 mcg). The dosage should then be titrated based on the TSH and FT4 values.
Target values: Induction phase: FT4 25-35 pmol/l; TSH 0.4-4.0 Maintenance: FT4: in the reference range, TSH 0.4-4.0
5 years
up to
12 years
Initial dose:
10
microg./kg/day
in 1
dose Induction phase in order to achieve normalization of FT4 and TSH. In severe hypothyroidism (FT4 < 8 pmol/l), the initial dose is repeated after 12 hours as a one-off..
Maintenance dose:
3
- 5
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day
The dose adjustment is about 1 mcg/kg/day, rounded off to the nearest unit of ± 6.25 mcg (a quarter of a tablet of 25 mcg). The dosage should then be titrated based on the TSH and FT4 values.
Target values: Induction phase: FT4 25-35 pmol/l; TSH 0.4-4.0 Maintenance: FT4: in the reference range, TSH 0.4-4.0
12 years
up to
18 years
Initial dose:
10
microg./kg/day
in 1
dose Induction phase in order to achieve normalization of FT4 and TSH. In severe hypothyroidism (FT4 < 8 pmol/l), the initial dose is repeated after 12 hours as a one-off..
Maintenance dose:
2
- 4
microg./kg/day
in 1
dose
Directions for administration:
Levothyroxine can be taken in the morning or evening with or without food, but should be taken the same way every day.
The dose adjustment is about 1 mcg/kg/day, rounded off to the nearest unit of ± 6.25 mcg (a quarter of a tablet of 25 mcg). The dosage should then be titrated based on the TSH and FT4 values.
Target values: Induction phase: FT4 25-35 pmol/l; TSH 0.4-4.0 Maintenance: FT4: in the reference range, TSH 0.4-4.0
Supplementation after thyrostatic drugs
Oral
1 year
up to
5 years
25
microg./day
in 1
dose
If the TSH is > 4 mU/litre, increase the levothyroxine.
5 years
up to
12 years
50
microg./day
in 1
dose
If the TSH is > 4 mU/litre, increase the levothyroxine.
12 years
up to
18 years
75
microg./day
in 1
dose
If the TSH is > 4 mU/litre, increase the levothyroxine.
Initial dose:
2.5
- 5
microg./kg/day
in 1
doseMaintenance dose: increase the starting dose (total daily dose) every 2-4 weeks by 50 mcg to the highest dose that gives no side effects..
Renal impaiment in children > 3 months
GFR ≥10 ml/min/1.73m2: Dose adjustment not required.
GFR <10 ml/min/1.73m2: A general recommendation on dose adjustment cannot be provided.
The complete list of all undesirable drug reactions can be found in the national Summary of Product Characteristics (SmPC) – click here
Side effects in children
In very rare cases (0.01-0.1%), a pseudotumor cerebri may occur, particularly in children [SmPC Eferox]. There have been reported cases of circulatory collapse in low birth weight premature infants [SmPC L-Thyroxin Henning]. In children, prolonged use of excessively high T4 doses can lead to disorders of bone maturation.
The complete list of all contra-indications can be found in the national Summary of Product Characteristics (SmPC) – click here
Contra-indications
No information available on specific contra indications in children.
The complete list of all warnings and precautions can be found in the national Summary of Product Characteristics (SmPC) – click here
Warnings & precautions in children
Signs of overdose: Nervousness, sleeplessness, tremor, tachycardia, sweating, vomiting, fever, weight loss and pseudotumor cerebri. Locust bean gum (Nutriton) and soya bind thyroid hormone and should not be taken at the same time as it.
In children, attention should be paid to any epiphysiolysis of the femoral head. Haemodynamic parameters should be monitored when levothyroxine treatment is initiated in premature infants with low birth weight, as poor adrenal function may lead to circulatory collapse.
Interactions
The complete list of all interactions can be found in the national Summary of Product Characteristics (SmPC) – click here
Mersebach, H., Intestinal adsorption of levothyroxine by antacids and laxatives: case stories and in vitro experiments, Pharmacol. Toxicol., 1999, 84, 107-109
Leger et al, European Society for Paediatric Endocrinology Consensus Guidelines on Screening, Diagnosis, and Management of Congenital Hypothyroidism, J Clin Endocrinol Metab, 2014, 99(2), 363-84
