Final Height in Patients With Congenital Hypothyroidism Diagnosed by Neonatal Screening

Linear growth and final height are reported as rather normal in patients with CH diagnosed through the screening and the target height is the most important factor determining linear growth. Data on final height in patients with CH suggest that adult height is significantly correlated with parental height and the mean L-Thyroxine daily dose administered over the first 6 months of treatment. The lowest recommended dose during this period is 8.5μg/kg/day. Periodical adjustments of L-Thyroxine daily dose should be guided by clinical observation and serum free T4 levels.

To our knowledge this is the first study from our center to assess final height in patients with congenital hypothyroidism diagnosed through the Egyptian neonatal screening program.

A complex network of endocrine signals stimulates the process of longitudinal growth including growth hormone, insulin-like growth factor-1, glucocorticoids, thyroid hormone, estrogen, androgens, vitamin D and leptin.

Thyroid hormones are essential for development and normal bone growth. Biochemical studies have shown that thyroid hormones can affect the expression of various bone markers in the serum, reflecting changes in bone remodeling which involves both osteoblastic and osteoclastic activities.

Thyroid hormones act through chondrocytes bearing thyroid hormone receptors (TRs) to modulate growth plate proliferation, differentiation and vascular invasion. Several mechanisms mediate these functions including direct action on the chondrocytes, osteoblasts and mast cells. It also works through interaction with other hormones and growth factors acting in endocrine, paracrine and autocrine fashions.