Background

Cystinosis is a metabolic disease caused by intracellular accumulation of cystine within lysosomes. Development of symptoms can be delayed significantly by a life-long therapy with cysteamine, a drug that enters the lysosome and reacts with cystine thereby enabling its export from the organelle.

Methods

During a period of 16 years, blood samples of 330 cystinosis patients were analyzed to investigate therapeutic adherence and metabolic control in patients treated with immediate-release cysteamine. The accepted therapeutic goal is to measure intracellular cystine levels in white blood cells every 3 months and to keep them below 0.5 nmol cystine/mg protein (= 1 nmol hemicystine/mg protein).

Results

42% of measurements were within the desired 3-month interval, 38% were done every 3–5 months, 11% every 6–8 months, 5% every 9–12 months and 4% after a 12-month interval only. 64.4% of the measurements were higher than the therapeutic target value. Median cystine levels increased with longer control intervals.

Conclusions

The majority of the cystinosis patients showed insufficient metabolic adjustment. Intracellular cystine levels were not done as often as recommended and were not within therapeutic range. Poor therapy adherence is likely to be caused by gastrointestinal side effects of immediate-release cysteamine. Incorrect intervals between drug intake and blood sampling could contribute to the results.

中文翻译：

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胱氨酸病：接受速释半胱胺治疗的患者的治疗依从性和代谢监测。

背景

胱氨酸病是一种由胱氨酸在溶酶体内积累引起的代谢性疾病。半胱胺的终身治疗可以显着延迟症状的发展，半胱胺是一种进入溶酶体并与胱氨酸反应从而使其能够从细胞器中输出的药物。

方法

在 16 年期间，对 330 名胱氨酸病患者的血液样本进行了分析，以研究接受速释半胱胺治疗的患者的治疗依从性和代谢控制。公认的治疗目标是每 3 个月测量一次白细胞中的细胞内胱氨酸水平，并将其保持在 0.5 nmol 胱氨酸/mg 蛋白（= 1 nmol 半胱氨酸/mg 蛋白）以下。

结果

42% 的测量在所需的 3 个月间隔内进行，38% 每 3-5 个月进行一次，11% 每 6-8 个月进行一次，5% 每 9-12 个月进行一次，4% 仅在 12 个月间隔后进行。64.4% 的测量值高于治疗目标值。中位胱氨酸水平随着控制间隔的延长而增加。

结论

大多数胱氨酸病患者表现出代谢调节不足。细胞内胱氨酸水平没有按照推荐的频率进行，并且不在治疗范围内。治疗依从性差可能是由速释半胱胺的胃肠道副作用引起的。药物摄入和血液采样之间的不正确间隔可能会导致结果。