Infantile osteopetrosis in four Thai infants

Four Thai infants, aged between 4 and 23 months, had progressive abdominal distension, pallor and delayed or regressed developmental milestones, with age at onset of 1 month, 3 months, 4 months and 1 month, respectively. Clinical findings consisted of growth and developmental retardation, anemia, frontal bossing, marked hepatosplenomegaly, and hearing and visual impairment. Laboratory findings revealed moderate anemia, leukocytosis and thrombocytopenia. The radiographic findings comprised generalized sclerosis of all bones, including the cranial base, and obliteration of the medullary canals and trabecular patterns. The first and second patients, who had swelling of the wrist joints and prominent costochondral junctions, had hypophosphatemia, elevated levels of serum alkaline phosphatase, and metaphyseal flaring on their radiographs, which was consistent with infantile osteopetrosis complicated by rickets. After Stoss therapy, there were biochemical and radiological responses suggesting vitamin D deficiency in the first patient, but not in the second. The third patient, who had hypocalcemia, hypophosphatemia and normal levels of serum alkaline phosphatase, received vitamin D at 3000 units per day, without improvement. Despite frequent blood transfusions, all patients continued to deteriorate and were finally lost to follow-up. Rickets should be identified and treated at the onset, because treatment of rickets leads to improvement in well-being and an adequate clinical response to bone marrow transplantation.