Vitamin D metabolism in biliary atresia: intestinal absorptions of 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3.

In children with biliary atresia, defective intestinal absorption of vitamin D and impaired hepatic uptake and 25-hydroxylation of vitamin D lead to a deficiency of vitamin D and rickets. We recently observed severe rickets in a 3-year-old boy with corrected biliary atresia resulting in jaundice, despite oral treatment with 1 alpha-hydroxyvitamin D3 (1 alpha-OHD3) or 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. He had low 25-hydroxyvitamin D (25-OHD) and high 1,25-(OH)2D serum levels. Intramuscular vitamin D2 administration produced radiological and biochemical evidence of recovery. Oral 1,25-(OH)2D3 (0.1 microgram/kg) and 25-OHD3 (10 micrograms/kg) tolerance tests were done to assess the ability to absorb vitamin D and the effectiveness of using these drugs orally. Eleven children with corrected biliary atresia, aged 9 months to 7 years, were studied. In oral 1,25-(OH)2D3 tolerance tests, the increments above the baseline serum levels of 1,25-(OH)2D were 140.7 +/- 27.4 pg/ml in nonjaundiced patients (n = 5). In jaundiced patients (n = 3), 1,25-(OH)2D3 absorption in two patients with high basal 1,25-(OH)2D values was lower than that of nonjaundiced patients; however, the absorption in the third patient with a low basal value was similar to that of nonjaundiced patients. In oral 25-OHD3 tolerance tests, the mean increase of serum 25-OHD was 48.9 +/- 30.6 ng/ml in nonjaundiced patients (n = 5) and 23.7 +/- 9.5 ng/ml in jaundiced patients (n = 4), the peak serum 25-OHD levels being reached 6-12 h after 25-OHD3 loading.(ABSTRACT TRUNCATED AT 250 WORDS)