Vitamin D Metabolism in Biliary Atresia

Abstract

SummaryIn children with biliary atrcsia, 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 atrcsia resulting in jaundice, despite oral treatment with 1α‐hydroxyvitamin D, (1α‐OHD,) or 1,25‐dihydroxyvitamin D, [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 (O.1 μg/kg) and 25‐OHD3 (10 μg/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 non‐jaundiced 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 non‐jaundiced 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. The increase of serum 25‐OHD in jaundiced patients tended to be less than that in nonjaundiced patients at 4 hours after 25‐OHD3 administration (15.1 ± 12.6 vs 48.9 ± 30.6 ng/ml), but the difference was not significant. In addition, oral treatment with 25‐OHD, (4 μg/kg/day) for 3 months resulted in marked increases in the serum 25‐OHD level and hone density in the jaundiced patients (n = 3).