title: 1,25-Dihydroxyvitamin D production after stimulation with synthetic human parathyroid hormone (1-34) in hypoparathyroid and renal tubular disorders.
abstract: 1,25-dihydroxyvitamin D production in response to two successive infusions of synthetic active 1-34 fragment of human PTH [hPTH-(1-34)] was evaluated in order to develop an understanding of the vitamin D metabolism and the rationale of vitamin D therapy in calcium disorders. Five normal controls, six hypoparathyroid patients, two patients with hypophosphatemic vitamin-D-resistant rickets, one patient with Lowe's synd. and one patient with primary Fanconi's synd. were investigated, and the following results were obtained. All normal controls showed a significant increase in serum 1,25(OH)2D[43 +/- 3.8 (m +/- SEM, n = 5, basal), 53 +/- 4.3 (three hours after the first PTH infusion), 65 +/- 7.7 (six hours) and 66 +/- 4.4 (nine hours) pg/ml]. All patients with PTH-deficient hypoparathyroidism showed a significant increase in serum 1,25(OH)2D, and serum 1,25(OH)2D values were within the normal range after hPTH-(1-34) stimulation. Serum 1,25(OH)2D remained low after hPTH-(1-34) infusions in a patient with pseudohypoparathyroidism type I who showed a significant increase in this value after infusion of dibutyryl cyclic AMP. On the other hand, a patient with normocalcemic pseudohypoparathyroidism type I had a high basal 1,25(OH)2D value, which increased further after hPTH-(1-34) infusions. An almost normal increase in serum 1,25(OH)2D was observed in two patients with hypophosphatemic vitamin-D-resistant rickets, one with Lowe's syndrome and the other with primary Franconi's syndrome. We conclude that these results ae important in obtaining an understanding of calcium and vitamin D metabolism in these disorders and that this PTH stimulation test is a useful method to use in evaluating renal responsiveness in 1,25(OH)2D production to PTH in various calcium disorders.
mesh_terms: D000293:Adolescent; D000328:Adult; D003994:Bucladesine; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000096:biosynthesis* / Q000097:blood; D002118:Calcium / Q000097:blood; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007011:Hypoparathyroidism / Q000378:metabolism*; D007015:Hypophosphatemia, Familial / Q000378:metabolism; D007223:Infant; D007674:Kidney Diseases / Q000378:metabolism*; D007684:Kidney Tubules / Q000503:physiopathology*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D010710:Phosphates / Q000097:blood; D011547:Pseudohypoparathyroidism / Q000378:metabolism; D019379:Teriparatide
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010710:Phosphates; D019379:Teriparatide; D003994:Bucladesine; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium