Acquired hypothyroidism refers to hypothyroidism that develops after the first year of life. It typically occurs in childhood or adolescence. The most common cause of acquired hypothyroidism is due to auto immunity. It is a condition that arises when the body's immune system attacks the thyroid cells. Autoimmune conditions can cause either a transient over-active or a transient or permanent under-active or non-functioning gland. An individual can have both an overactive and an under active phases during this autoimmune-related destructive phase.
I treated a patient with a profound case of acquired hypothyroidism several years ago. Before endocrine consultation, her pediatrician had noticed the patient was not being growing well. This prompted an evaluation to include thyroid function testing. The test results revealed severe hypothyroidism with undetectable endogenous thyroid hormone production (extremely elevated TSH and low ft4).
During my consultation with the family, the mother informed me that her daughter transitioned to sedentary type activities over the last several years. She was previously more active but over the years developed a preference for reading and drawing. Due to her severe hypothyroidism, she was placed on thyroid hormone with a with a very gradual increase in the dose to ensure tolerability. Gradually over the next several months her thyroid function normalized on thyroid hormone replacement. In parallel, her linear growth picked up nicely. She also started to have other physical changes. Her face became less coarse appearing, puffy as her thyroid labs normalized. Mother also noted that she became for active and now did not sit for prolonged times.
Acquired hypothyroidism is treated with thyroid hormone replacement. Thyroid hormone replacement is very important for a growing child because it is needed for muscle function, bone health and growth and development. It does require close lab monitoring for dose adjustments. A child will outgrow their dose over time, but dosage adjustments are strictly based on lab results and are not weight based per se. During puberty, thyroid function tests are done more frequently as a child is more likely to outgrow their dose and need dose adjustments.