Hypothyroidism with scholastic excellence.

A 9-year-old boy had presented with not gaining adequate height with complaints of constipation from 5 years, lethargy and loss of appetite from past 6 months. He was diagnosed to have hypothyroidism with high thyroid antibody levels. Though he was stunted his neurocognition and scholastic performance was excellent as evidenced by his school rank cards. His physical symptoms had improved after thyroxin supplement.

Hypothyroidism is the condition in which there is decreased production or activity of the thyroid hormones.[1] Thyroid hormone act on all body tissues and influence calorigenesis, basal metabolic rate, protein catabolism, gluconeogenesis, fatty acid metabolism and other endocrine hormones.[2] The effect of thyroid hormone deficiency depends on the degree and the time duration of the deficiency.[1] Here, we are presenting a case of hypothyroidism which had manifested in late childhood.

Case Report

A 9-year-old boy 1st born to 3° consanguineous marriage was brought with complaints of not gaining height for the age. Mother noted weight gain, lethargy and loss of appetite from last 6 months. There was history of constipation. Birth history was uneventful. Child was developmentally normal with good scholastic performance. There was history of vitiligo for mother. On examination, child was alert, oriented, with a height of 103 cm which is <3rd centile as per the Centers for Disease Control and Prevention (CDC) chart [Figure 1], weight of 19 kg which is <3rd centile as per the CDC chart, mid parental height = 160 cm which is <3rd centile as per the CDC chart, upper segment: Lower segment = 1.1 which is normal for his age, Head circumference 50 cm which is normal for his age, heart rate 86 beats/min, respiratory rate 22/min, blood pressure 90/70 mm Hg, cardiac resynchronization therapy <2 s, +++/++, pallor present, No icterus, cyanosis, clubbing, lymphadenopathy, and pedal edema. Systemic examination was normal. Evaluation for short stature was done. Total count 5300 cells/mm3, neutrophil 45%, lymphocytes 53%, eiosinophils 1%, monocytes 1%, erythrocyte sedimentation rate 16 mm, red blood cells 3.48 cells/mm3, packed cell volume 30%, mean corpuscular volume 87, mean corpuscular hemoglobin concentration 32%, platelets 53000/mm3, hemoglobin 9.7 g/dl, bone age by wrist >3 years <4 years [Figure 2]. Thyroid function test showed a decreased free T3-2.48 pg/ml (2.9–6 pg/ml), decreased free T4-0.49 ng/dl (0.81–1.68 ng/dl) and an increased thyroid stimulating hormone (TSH) - >100 (0.35–5.6 microIU/ml). The anti-thyroid antibodies were done. Thyroglobulin antibody level was raised 94.49 IU/ml (normal up to 4.11 IU/ml), thyroid peroxidase (TPO) antibody-more than 1000 IU/ml (normal up to 5.61 IU/ml). Hence, the child was diagnosed to have autoimmune thyroiditis and was started on L Thyroxine replacement therapy of 100 μg/day. The child was on follow-up from the past 3 months and he has gained 2 cm of height.

Figure 1

The child with hypothyroidism and short stature

Figure 2

X-ray of wrist showing delayed bone age

Discussion

The prevalence of hypothyroidism in young people <22 years is 0.135% and in age group 11–18 years it is 0.113%. Male to female ratio is 1:2.8. Acquired hypothyroidism was the most common etiology and majority of them had autoimmune basis.[3] Autoimmune thyroiditis can start as subclinical hypothyroidism; later frank hypothyroidism can develop.[4] Slowing of rate of growth is a sign of severe under-activity of the thyroid gland.[5] Although the measurement of T3, T4, TSH, TPO-Ab, Tg-Ab are evaluated for autoimmune status, hypoechogenic pattern in ultrasound is an early marker of thyroid impairment.[4] Studies have shown that the neurocognitive functioning, as well as psychological wellbeing, may not be completely restored in patients with hypothyroidism despite treatment with thyroxine.[6] Some have suggested that the duration of untreated hypothyroidism might be a more significant determinant of the outcome and a permanent height deficit develop related to the duration of T4 deficiency before treatment.[7]

Conclusion

Hypothyroidism can present at a later stage which might go unnoticed especially in Indian scenario. Scholastic performance may be normal in hypothyroidism. Regular anthropometric assessment may give a clue. So efforts should be made to detect hypothyroidism at its subclinical stage itself, with the help of mass screening at school level, to prevent the neurocognitive effects and shunted growth of hypothyroidism. Neonatal thyroid screening helps in diagnosing hypothyroidism only at birth.