Challenges in the Suppression of Thyroid Stimulating Hormone in a Thyroid Cancer Patient with Chronic Renal Failure - Abstract
Thyroid stimulating hormone (TSH) suppression therapy with excessive administration of thyroxine (levothyroxine sodium; T4) is commonly initiated after surgical removal of differentiated thyroid carcinoma (DTC) to delay metastasis progression. In the present report, we describe a case with chronic renal failure (CRF) and poor TSH control despite sufficient T4 administration for TSH suppression. A 37-year-old man had been managed with insulin therapy and modified diet for the treatment of diabetes complicated with diabetic eye disease and diabetic nephropathy. He underwent total thyroidectomy and
neck dissection for multiple cervical lymph node (LN) metastases from thyroid cancer and was referred to our hospital for two sessions of I-131 radioiodine therapy (RIT). For TSH suppression therapy, he received 125 ?g/day of T4 orally. A blood test at initial admission indicated that the fT3 levels were 2.0 (normal range, 2.6–4.2) pg/mL, fT4 levels were 1.0 (0.9–1.7) ng/mL, TSH levels were 48.8 (0.32–4.04) ?IU/mL,
and thyroglobulin (Tg) levels were 73.8 (0–30) ng/mL. The test for anti-thyroglobulin antibody yielded negative results and the creatinine (Cr) levels were slightly elevated at 1.24 mg/dL (normal range, 0.5–1.1). Due to the high levels of TSH observed, the T4 dosage was increased from 125 ?g/day to 150 ?g/day after RIT, but it failed to effectively reduce the TSH level. The dose of T4 administered was eventually increased
to 250 ?g/day at 18 months after the initial examination, but the TSH level remained at 16.92 ?IU/mL. Therefore, T4 dosage was reduced to 100 ?g/day, and 100 ?g/day of liothyronine sodium (T3) was added to the treatment regimen, which successfully reduced the TSH level to 0.004 ?IU/mL and Tg level to 67 ng/mL in 6 months.