26. Kết quả điều trị còi xương phụ thuộc vitamin D loại 1A ở Bệnh viện Nhi Trung ương

Abstract

Vitamin D-Dependent Rickets Type 1A (VDDR1A) is a rare autosomal recessive disorder. Pathogenic variants in the CYP27B1 gene cause a deficiency of the enzyme 1α-hydroxylase, which converts 25(OH)D to 1,25(OH)2D. This deficiency results in long bone deformities, delayed physical growth, delayed walking, and even seizures due to hypocalcemia. Laboratory findings include severe hypocalcemia, elevated alkaline phosphatase activity, and PTH, with normal or elevated 25(OH)D levels. Treatment with calcitriol improves both clinical and laboratory outcomes. A case series study, comparing pre- and post-treatment conditions, was conducted on 19 children diagnosed with VDDR1A at the Center for Endocrinology-Metabolism-Genetics and Molecular Therapy, National Children's Hospital until October 2024. The study included 10 males (52.6%) and 9 females (47.4%), with a median diagnosis age of 19.2 months old. At diagnosis, all children were significantly short, with a median height standard deviation of -3SD (WHO). Typical symptoms included bow legs or knock knees, and wrist and ankle swelling in most children. All patients had homozygous or compound heterozygous pathogenic variants in the CYP27B1 gene. Most patients had severe hypocalcemia, normal or low blood phosphate, significantly elevated ALP and PTH, and normal 25(OH)D levels. X-rays showed fraying and widening of the long bone ends. Treatment involved calcitriol at 0.5 - 2 mcg/day and elemental calcium at 50 - 100 mg/kg/day. Significant improvement in bone deformities, blood calcium levels, ALP, and PTH were observed after 12 to 18 months of treatment. In conclusion, treatment of VDDR1A with calcitriol and elemental calcium effectively improves blood calcium levels and bone deformities.