DrMehak ,DrC Jayakumar,DrPraveena Bhaskaran ,Dr Navya George
AIMS KOCHI
Kerala
India
A female ba weighing 3.05kgs delivered at 38 weeks and 3 days of gestation via Elective LSCS in view of Previous LSCS to a 35 year old G3P1L1A1 mother who is known case of difficult to control Hypothyroidism since 6 years
Ba cried immediately after birth.
Ba had wide open anterior as well as posterior fontanelles(1cm×1cm) on examination.
There was increased pooling of secretions at birth and a NGT was inserted to exclude TEF which passed easily.
She was jittery after birth and GRBS checked was 40mg/dL so given one feed with formula milk.
On Day 2 of life, ba had 10% weight loss and serum sodium was elevated(145.3mmol
Hence ba was restarted on top feeds.
Her 48 hour labs were assessed and TSB, DSB were normal.
However, TFT revealed a TSH value of >100uIU/ml with slightly elevated T4 at 2.9ng/dl(0.89-2.2ng/dl).
TFT was repeated to rule out technical errors but similar results were obtained
Mother revealed that her first ba also had a similar TSH value at birth which spontaneously normalised Day 5 of life.
It was decided to repeat the ba’s labs after 24 hours. USG Neck was performed in the interim and found to show normal thyroid tissue in the neck.
Xray Knee including Ankle were also taken which showed absence of ossification centres at the distal end of femur and proximal end of tibia.
Repeat TSH values continued to be elevated(96.96uIU/ml) with normal T4 of 2.08ng/dl and normal Anti-TPO values.
Ba was started on Levothyroxine supplementation with 37.5mcg tablets (12.5mcg/kg).
On repeating the values prior to discharge, TSH was 44.25uIU/ml but T4 was 3.55ng/dl. The previous dose was continued till Day 7 of life when repeat investigations revealed TSH of 13.43uIU/ml with persistently elevated T4 values(2.73ng/dl).
Ba was diagnosed with Congenital Hypothyroidism with Isolated Hyperthyrotropinemia and Thyroxine dosage was decreased to 25mcg.
Most common cause of Congenital Hypothyroidism is Thyroid Dysgenesis either due to agenesis or hypoplasia of the gland. Dyshormogenesis is the other cause which is inherited usually in an autosomal recessive fashion. With dyshormogenesis, as the thyroid gland responds normally to elevated TSH values, goitre is common.
While most infants are asymptomatic at birth due to maternal T4 which is about 33% of the normal value, subtle signs on clinical examinations are important like
1. Wide open fonatenelles especially posterior fontanelle more than 0.5cm.
2. Increased head size due to myxedema of brain.
3. Prolonged jaundice due to delayed maturation
4. Hoarse cry
5. Increased sleep
6. Poor appetite
7. Sluggish
8. Feeding difficulties
9. Choking spells
10. Somnolence
11. Respiratory difficulties due to macroglossia
12. Constipation
13. Large abdomen with umbilical hernia
14. Edematous genitals
15. Macrocytic anemia
60% of these babies have delayed osseus development with absence of distal femur and proximal tibial epiphyses.
Treatment is Levothyroxine tablets that should not be diluted with soy protein formula, iron or calcium and starting from 37.5mcg to 50mcg per day. The level should thus be checked every 1-2 months for the first 6 months followed 2-4 months between 6 months and 3 years of age.
Earliest diagnosis ensure moral mentation