As rickets progresses, the following manifestations may appear: 1. low muscle tone, joint ligament laxity, abdominal enlargement like frog belly. 2. 2. Delayed motor development and late independent walking. 3. Severe rickets is often accompanied by anemia, weakened systemic immunity, diarrhea and pneumonia. 4, the child’s blood calcium is too low, can appear low calcium spasms, facial and hand and foot muscle convulsions or generalized convulsions, the attack is brief about a few minutes to stop, but also frequent attacks, severe convulsions can cause asphyxia due to laryngospasm.