Causes of cretinism include athyreosis, cryptothyroidism with inadequate thyroid hormone production, and dyshormonogenetic causes. Basal thyroid function tests will reveal low levels of T4, together with a raised level of thyroid-stimulating hormone. Bone-age radiographs, particularly of the knees, are valuable. The distal femoral epiphyses are calcified in nearly all normal-term individuals, but not in cretins.
