Parents should not directly judge whether their children have hypothyroidism or not, but should be diagnosed by the doctor in conjunction with their clinical manifestations, laboratory tests, X-ray examinations, and nuclear examination. 1. Clinical manifestations (1) Physical appearance: short stature, long trunk, short limbs. Sparse hair, yellowish color, low nose, wide eye spacing, thick tongue, etc. (2) Neurological symptoms: apathetic expression, mental retardation, impaired motor development, delayed nerve reflexes, etc. (3) Low physiological function: fear of cold, poor spirit, drowsiness, lack of appetite, constipation, less response to things around, etc. 2. Laboratory tests: serum T3 (serum total triiodothyronine), T4 (serum total thyroxine), TSH (thyroid-stimulating hormone) measurements: a decrease in T4 and a significant increase in TSH can confirm the diagnosis. 3. X-ray examination: on X-ray, the bone age of the child is often younger than the actual age. 4. Nuclide test: After injection of 99mTc (an isotope of technetium), the size, shape and development of the thyroid gland of the child can be detected by SPECT (Single Photon Emission Computed Tomography). If hypothyroidism is suspected, parents should take their children to the hospital for diagnosis and standardized treatment.