Thyroid Hormone Replacement in Patients Following Thyroidectomy for Thyroid Cancer

Abstract

Thyroid hormone replacement therapy in patients following thyroidectomy for thyroid cancer, although a potentially straightforward clinical problem, can present the clinician and patient with a variety of challenges. Most often the problems are related to the dose and preparation of thyroid hormone (TH) to use. Some patients feel less well following thyroidectomy and/or radioiodine ablation than they did before their diagnosis. We present evidence that levothyroxine (L-T4) is the preparation of choice, and keeping the thyroid-stimulating hormone (TSH) between detectable and 0.1 mU/L should be the standard of care in most cases. In unusual circumstances, when the patient remains clinically hypothyroid despite a suppressed TSH, we acknowledge there may be as yet unidentified factors influencing the body’s response to TH, and individualized therapy may be necessary in such patients.

A single report of skin disease associated with a functional thyroid carcinoma in a dog

“…Thyroid supplementation was commenced postoperatively due to inducing hypothyroidism and to inhibit tumour growth. Thyroid cancer will express TSH receptor on the cell membrane and responds to TSH stimulation by increasing expression of thyroid-specific proteins and by increasing the rates of cell growth 7) . It is believed that by suppressing TSH secretion it will decrease the rate of progression of thyroid tumour growth 3,7) .…”

“…Thyroid cancer will express TSH receptor on the cell membrane and responds to TSH stimulation by increasing expression of thyroid-specific proteins and by increasing the rates of cell growth 7) . It is believed that by suppressing TSH secretion it will decrease the rate of progression of thyroid tumour growth 3,7) . Based on this belief the post-pill T4 levels were maintained at the high end of the normal reference range to continue suppression of TSH secretion.…”

Thyroid‐stimulating hormone suppression therapy for differentiated thyroid cancer: The role for a combined T3/T4 approach

“…The T3 has a half-life of 19 hours and, thus, requires administration in 2 or 3 daily doses. 2 Intestinal absorption of T3 and T4 are similar (90% and 80%, respectively), however, after oral administration of T4, the serum concentration rises by 20%-40%, whereas in the case of T3 the serum concentration rises by 250%-600%. 3 A 2002 meta-analysis confirmed the efficacy of TSH suppression in preventing thyroid cancer disease progression or recurrence.…”

“…Levothyroxine has a blood half‐life of 7 days; therefore, a single daily dose is sufficient. The T3 has a half‐life of 19 hours and, thus, requires administration in 2 or 3 daily doses . Intestinal absorption of T3 and T4 are similar (90% and 80%, respectively), however, after oral administration of T4, the serum concentration rises by 20%‐40%, whereas in the case of T3 the serum concentration rises by 250%‐600% …”

Desensibilización a levotiroxina. Caso clínico

“…La tiroidectomía total está recomendada en pacientes con tumores de 4 centímetros o más, o en aquellos con alguna característica de mayor extensión 2 , dejando a los pacientes dependientes del reemplazo hormonal exógeno con levotiroxina 3 . Esta prohormona sintetizada en la tiroides circula en la sangre asociada en 99% a proteínas de transferencia 4,5 y su vida media en un paciente eutiroideo es de aproximadamente 7 días. En ausencia de tiroides, la levotiroxina exógena es convertida eficientemente a triyodotironina (T3), la hormona activa, manteniendo niveles de T3 estables postadministración.…”