TSH as high as 6.4mU/L may cause increased cholesterol, provided that there is a decrease in thyroid hormones and hypothyroidism is present. The normal reference value of TSH is 0.3-5.0mU/L, which may vary slightly from hospital to hospital. 6.4mU/L is higher than the normal level, and because of the negative feedback effect of thyroid hormones on TSH, when TSH is elevated above the upper limit, it may indicate a decrease in thyroid hormone secretion, i.e. hypothyroidism. Under normal circumstances, thyroid hormones reduce serum cholesterol levels by increasing fat metabolism in the body and removing cholesterol from the serum, so when thyroid hormone secretion decreases, serum cholesterol may be elevated. If TSH or cholesterol is elevated, it is recommended to go to the hospital for clarification of the cause and, if necessary, be directed by a doctor for treatment to avoid adverse effects on health.