serum level

例句：

1. 1. The doctor ordered a test to check her serum level.
   医生下令做测试来检查她的血清水平。
2. 2.The patient's serum level was elevated due to an infection.
   患者的血清水平因感染而升高。
3. 3.Serum levels of vitamin D are often used as indicators of health.
   血清中的维生素D水平常被用作健康的指示器。