Influence of Lean Body Mass and Disease Etiology on Levothyroxine Requirements in Patients with Hypothyroidism

Year 2025, Volume: 7 Issue: 3, 386 - 393, 13.10.2025

Ülkem Şen Uzeli , Duygu Tutan

https://doi.org/10.52827/hititmedj.1705311

Abstract

Objective: It was aimed to evaluate the dose requirement depending on the etiology and to compare lean body mass and total body weight in the calculation of drug dose in patients receiving levothyroxine sodium replacement.
Material and Method: A total of 124 patients who were receiving levothyroxine sodium treatment for total thyroidectomy, hypothyroidism due to radioactive iodine therapy treatment and autoimmune hypothyroidism were included in cross-sectional study. Patients' drug doses, height, weight, thyroid stimulating hormone, T4 and T3 values were recorded on the hospital documentation system. Lean Body Mass was calculated and the doses of drugs were calculated based on total body weight and Lean Body Mass. Patients were separated into 3 groups as normal weight, overweight and obese according to body mass index.
Results:Patients with Hashimoto's thyroiditis required lower daily levothyroxine doses compared to those who had undergone total thyroidectomy. Similarly, the daily levothyroxine dosage per kilogram of lean body mass and total body weight was significantly lower in the Hashimoto's group than in the total thyroidectomy group. While the RAI group showed intermediate values that did not differ significantly from either group
Conclusion: This study shows that the use of lean body mass is more significant than body mass index in determining the dose of levothyroxine in hypothyroid patients. Findings show that the dose of levothyroxine varies according to the etiology of hypothyroidism and that treatment doses should be determined accordingly.

Keywords

Hypothyroidism , Lean Body Mass , Levothyroxine Sodium

Hipotiroidili Hastalarda Yağsız Vücut Kütlesi ve Hastalık Etiyolojisinin Levotiroksin Gereksinimlerine Etkisi

Abstract

Amaç: Levotiroksin sodyum replasmanı alan hastalarda etyolojiye bağlı doz gereksinimini değerlendirmek ve ilaç dozunun hesaplanmasında yağsız vücut kütlesi ile toplam vücut ağırlığını karşılaştırmak amaçlandı.
Gereç ve Yöntemler: Total tiroidektomi, radyoaktif iyot tedavisine bağlı hipotiroidi ve otoimmün hipotiroidi nedeniyle levotiroksin sodyum tedavisi alan toplam 124 hasta kesitsel çalışmaya dahil edildi. Hastaların ilaç dozları, boy, kilo, tiroid uyarıcı hormon, T4 ve T3 değerleri hastane dokümantasyon sistemine kaydedildi. Yağsız Vücut Kütlesi hesaplandı ve ilaç dozları toplam vücut ağırlığı ve Yağsız Vücut Kütlesi değerlerine göre hesaplandı. Hastalar vücut kitle indeksine göre normal kilolu, kilolu ve obez olmak üzere 3 gruba ayrıldı.
Bulgular: Hashimoto tiroiditi olan hastaların, total tiroidektomi geçiren hastalara kıyasla daha düşük günlük levotiroksin dozlarına ihtiyaçları vardı. Benzer şekilde, yağsız vücut kütlesi ve toplam vücut ağırlığının kilogramı başına günlük levotiroksin dozu, Hashimoto grubunda total tiroidektomi grubuna göre anlamlı derecede düşüktü. RAI grubu ise her iki gruptan da anlamlı farklılık göstermeyen orta düzeyde değerler gösterdi.
Sonuç: Bu çalışma, hipotiroid hastalarında levotiroksin dozunun belirlenmesinde yağsız vücut kütlesi kullanımının vücut kitle indeksinden daha önemli olduğunu göstermektedir. Bulgular, levotiroksin dozunun hipotiroidizmin etyolojisine göre değiştiğini ve tedavi dozlarının buna göre belirlenmesi gerektiğini göstermektedir.

Keywords

Hipotiroidizm , Levotiroksin Sodyum , Yağsız Vücut Kütlesi.

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