Abstract
Our previous study attempting to explain the paucity of reports of rickets in CF patients revealed elevated serum total vitamin D activity determined by bioassay (Pediat.Res.11:443, 1977). A more precise evaluation was sought by determining serum 25-OHD levels, the major circulating vitamin D metabolite, by a specific protein binding assay. Fasting blood was obtained from 17 patients with proved pancreatic insufficiency (PI) and 2 patients without PI aged 6-47 years. All patients with PI had received pancreatic enzyme and multivitamin supplements. All patients had normal serum Ca and P levels and none had radiographic evidence of rickets or osteomalacia.
The mean 25-OHD level in the lower range of normal in CF patients with PI with vitamin D supplementation is similar to findings for other fat soluble vitamins. 4 patients had levels below the normal range, with 1 being undetectable. CF patients without PI had high levels of 25-OHD. The observed difference between the results in our studies assessing vitamin D status is at least partially attributable to the assay for 25-OHD being specific, whereas the bioassay is non-specific and measures the sum of the activities due to vitamin D2 and D3 and their metabolites.
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Hubbard, V., Farrell, P. & di Sant'Agnese, P. 439 SERUM 25-HYDROXYCHOLECALCIFEROL(25-OHI)) LEVELS IN PATIENTS WITH CYSTIC FIBROSIS(CF). Pediatr Res 12 (Suppl 4), 437 (1978). https://doi.org/10.1203/00006450-197804001-00444
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DOI: https://doi.org/10.1203/00006450-197804001-00444
