1. Early (early)
It is found in infants within 6 months, especially within 3 months. Most of them are manifestations of increased nerve excitability, such as irritability, annoyance, sweating to stimulate the scalp and shaking your head. At this stage, there is often no bone lesion, the bone X-ray can be normal, or the calcification zone is slightly blurred; Serum 25-OH-D3 decreased, PTH increased, blood calcium decreased, blood phosphorus decreased, and alkaline phosphatase was normal or slightly higher.
2. Active period (exciting period)
When the disease continues to worsen, PTH hyperfunction and abnormal metabolism of calcium and phosphorus appear typical bone changes. Skull changes are the main causes of rickets in infants under 6 months old, and the front fontanel is soft and the skull is thin, which makes them feel like "table tennis" when lightly pressed. After 6 months of age, there may be a ping-pong feeling around the suture, but the central part of the frontal bone and parietal bone often thickens gradually. By 7 ~ 8 months, the head shape becomes a "square skull" and the head circumference increases normally. The epiphyseal end swells due to the accumulation of bone-like tissue, and a circular bulge can be touched at the junction of ribs and costal cartilage along the rib direction, which is like a beaded protrusion from top to bottom, especially the 7th ~10 rib, which is called rickets beading. In severe cases, blunt circular bulges can also be formed on the wrists and ankles, which are called hand and ankle bracelets. 1 year-old children can see the sternum and adjacent cartilage protruding forward, forming a "chicken breast" deformity; A horizontal depression is formed at the lower edge of the thoracic cavity in children with severe rickets, that is, costal diaphragm sulcus or Hausdorff sulcus.
After children can sit and stand, spinal deformity can be caused by ligament relaxation. Due to osteomalacia and muscle joint relaxation, after 1 year-old, both lower limbs are loaded after standing and walking, and the femur, tibia and fibula may bend, resulting in severe genu varus ("O" shape) or genu valgus ("X" shape)-like lower limb deformity. It may be because of severe low blood phosphorus that muscle glucose metabolism is disordered, so that the whole body muscles are relaxed, muscle tension is reduced and muscle strength is weakened.
In this period, except for the slightly lower serum calcium, the changes of other indexes are more significant. X-ray showed that the calcified zone of long bone disappeared, and the metaphyseal end showed brush-like and cup-shaped changes. Bone thinning and cortical thinning; There may be diaphysis bending deformity or green branch fracture, and the fracture may have no clinical symptoms.
3. Recovery period
After treatment or sunlight exposure in any of the above periods, the clinical symptoms and signs gradually eased or disappeared. Blood calcium and phosphorus gradually returned to normal, and alkaline phosphatase decreased to normal level in1~ 2 months. After 2 ~ 3 weeks of treatment, the X-ray changes of bones were improved, and irregular calcification lines appeared. After that, the calcification zone became dense and thickened, and gradually returned to normal.
4. Sequela period
More common in children after 2 years old. Due to severe rickets in infancy, different degrees of skeletal deformity remain. No clinical symptoms, normal blood biochemistry, X-ray examination of bone metaphyseal lesions disappeared. [4]