Prospective study reveals mildly suppressed thyrotropin best preserves metabolic status in athyreotic patients on levothyroxine, suggesting normal targets reflect mild hypothyroidism.
Key Points
To determine whether athyreotic patients with normal, mildly suppressed, or strongly suppressed thyrotropin (TSH) levels on levothyroxine monotherapy are closest to their preoperative euthyroid state.
Prospective study of 133 consecutive euthyroid patients with papillary thyroid carcinoma undergoing total thyroidectomy.
Serum lipoproteins, sex hormone-binding globulin (SHBG), and bone metabolic markers measured preoperatively were compared with levels at 12 months postoperatively during levothyroxine therapy across three TSH groups.
Patients with strongly suppressed TSH (≤0.03 μIU/mL) showed significant postoperative increases in SHBG (p < 0.001) and bone alkaline phosphatase (p < 0.01).
Patients with normal TSH (0.3 < TSH ≤ 5 μIU/mL) had significant postoperative increases in low-density lipoprotein cholesterol (p < 0.05) and decreases in tartrate-resistant acid phosphatase-5b (p < 0.05).
Patients with mildly suppressed TSH (0.03 < TSH ≤ 0.3 μIU/mL) and free T3 levels matching preoperative levels showed no significant change in any metabolic marker relative to preoperative levels.