患儿男,12岁,因乏力3月余、加重伴四肢活动障碍1个月于2000年5月29日入院。患儿3个月前无诱因出现乏力,以四肢近端肌群为主,无肌痛,无发热,无心悸、胸闷。1个月前乏力加重,上楼梯需手扶栏杆,伴蹲位膝关节痛,伸位肘关节痛,无跛行、晨僵,无视物模糊,无呕血、黑便,无头痛、头晕。? Male, 12 years old, due to fatigue for more than 3 months, aggravated with limb movement disorders 1 month on May 29, 2000 admission. Children 3 months ago, there was no incentive to induce fatigue, mainly to the proximal limb muscles, no muscle pain, no fever, no heart palpitations, chest tightness. 1 month ago, fatigue increased, the need to go up the stairs handrail, with squat knee pain, extension elbow pain, no claudication, morning stiffness, blurred vision, no vomiting, melena, no headache, dizziness. ?