Zanotti-Fregonara Paolo, Duron Françoise, Keller Isabelle, Khoury Alexandre, Devaux Jean-Yves, Hindié Elif
Department of Nuclear Medicine, St. Antoine Hospital, Paris, France.
Nucl Med Commun. 2007 Apr;28(4):257-9. doi: 10.1097/MNM.0b013e32804c58c2.
Stimulation testing in the first year following thyroid ablation has important prognostic value in thyroid cancer patients. Recombinant human TSH (rhTSH) is better tolerated than thyroid hormone withdrawal but provides only transient stimulation so that the TSH threshold of 30 mIU x l(-1) which defines adequate testing during thyroid hormone withdrawal is not appropriate for rhTSH stimulation. We looked at rhTSH levels after a standard two intramuscular injections of 0.9 mg rhTSH.
Plasma rhTSH levels were measured 24 h after the second injection in 143 consecutive patients.
rhTSH levels showed large inter-patient variation (range: 44-240; mean+/-SD: 131+/-48). There was a strong inverse correlation between TSH levels and body weight (P<0.001). Levels lower than 80 mIU x l(-1) (corresponding to 1 SD below average) were recorded in 24 patients (16.8%). These patients had an average body weight of 79.7 kg, as compared to 67.9 kg for those patients with TSH levels higher than 80 mIU x l(-1). A withdrawal test in the first year after thyroid ablation was available in 64 patients. Only one patient (1.6%) had inadequate endogenous TSH stimulation, and there was no dependence of endogenous plasma TSH levels upon weight.
Contrary to endogenous stimulation, TSH levels after rhTSH injection vary with body weight. The dosage of rhTSH may need to be adapted in patients with more than 80 kg body weight.
甲状腺切除术后第一年的刺激试验对甲状腺癌患者具有重要的预后价值。重组人促甲状腺激素（rhTSH）的耐受性优于甲状腺激素撤药，但仅提供短暂刺激，因此甲状腺激素撤药期间定义充分试验的30 mIU×l⁻¹的促甲状腺激素（TSH）阈值不适用于rhTSH刺激。我们观察了标准的两次肌内注射0.9 mg rhTSH后的rhTSH水平。
对143例连续患者在第二次注射后24小时测量血浆rhTSH水平。
rhTSH水平在患者间差异很大（范围：44 - 240；均值±标准差：131±48）。TSH水平与体重之间存在强烈的负相关（P<0.001）。24例患者（16.8%）的TSH水平低于80 mIU×l⁻¹（比平均水平低1个标准差）。这些患者的平均体重为79.7 kg，而TSH水平高于80 mIU×l⁻¹的患者平均体重为67.9 kg。64例患者在甲状腺切除术后第一年进行了撤药试验。只有1例患者（1.6%）内源性TSH刺激不足，内源性血浆TSH水平与体重无关。
与内源性刺激相反，rhTSH注射后的TSH水平随体重变化。体重超过80 kg的患者可能需要调整rhTSH的剂量。
