Endocrine Abstracts

Introduction: Thyroid hormones are critical for early brain development, somatic growth, and bone and pubertal maturation. Primary hypothyroidism is a well-known cause of poor linear growth in children. This case highlights role of thyroid hormone replacement to improve final height in the setting of profound hypothyroidism.

Case: We report the case of 16 years old Caucasian girl initially evaluated for primary amenorrhea and delayed growth of 139 cm putting her below the second centile on growth chart. She has had delayed growth throughout which was considered as developmental delay however other developmental milestones were acquired appropriately. Her non-identical twin brother had height of 180 cm. Mother and father’s reported height was 156 cm and 182 cm respectively. On examination she had normal external genitalia and breast Tanner stage 2. Her Body Mass Index was 20. Investigation showed profound hypothyroidism with serum TSH of over 100 miu/l (0.35–4.5 miu/l) and free T4 of 0.8 pmol/l (10.5–26 pmol/l). MRI Pituitary was normal. She was started on Levothyroxin. Her linear growth velocity immediately improved to up to 16 cm/year, and she rapidly progressed through puberty, achieving menarche 18 months after starting treatment. She was also started on Growth Hormone replacement following Insulin Tolerance Test which showed partial Growth Hormone deficiency with peak level 8 mcg/l. She gained further 4.5 cm height giving a final height 158.5 cm at the age of 18 years which is close to the calculated Mid Parental Height of 162 cm.

Conclusion: Early diagnosis and treatment is essential to achieve final height in children with severe Primary Hypothyroidism, as late diagnosis and treatment during puberty invariably results in incomplete catch up growth and attenuated final height. Our patient responded well to Levothyroxin alone with further benefit from Growth Hormone replacement.