Cardiovascular clinics and wards often encounter older children, especially adolescents, who complain of a fast heartbeat and present to cardiovascular specialists with a fast heartbeat. Instead of going to the endocrinology clinic first. These children do not necessarily have hyperphagia, lethargy, or even excessive sweating, nor do they have proptosis, etc. They may only have a fast heartbeat and palpitations. Hyperthyroidism must be thought of at this point. Routine tests should be done to check the five tests of thyroid function. Or add thyroid antibodies. Such cases can occur in both boys and girls. We have screened and routinely tested the thyroid function in such cases, and they were all diagnosed early and referred to the endocrinology department in time. None of the cases showed delayed diagnosis.