Central hypothyroidism and growth hormone treatment : clinical care

Central hypothyroidism (CH) is a rare cause of hypothyroidism characterized by a defect of thyroid hormone production due to an insufficient TSH stimulation. CH can be congenital in the case of genetic defects or acquired in the case of lesions affecting either pituitary or hypothalamus. Diagnosis is usually made on a biochemical basis showing defective thyroid hormone circulating levels associated to inappropriately low TSH levels. Treatment of CH takes advantage of thyroid hormone replacement even though treatment cannot be tuned as easily as in primary hypothyroidism because the evaluation of circulating TSH has a very limited value in central defects. Interestingly, GH deficiency may mask subclinical forms of CH that reach a biochemical evidence only after institution of GH replacement therapy.