Calcitriol Vitamin D (1,25 di-OH Vitamin D)
- 1,25(OH) Vitamin D
- 1,25-Dihydroxy Vitamin D
- Vitamin D, 1,25-Dihydroxy
No isotopes administered 24 hours prior to venipuncture
Aids in the diagnosis of primary hyperparathyroidism, hypoparathyroidism, pseudohypoparathyroidism, renal osteodystrophy, and vitamin D-resistant rickets.
1,25-dihydroxy vitamin D is increased in sarcoidosis and hyperparathyroidism. It may be elevated in cases of hypercalcemia associated with malignant lymphoma. It is decreased in rickets, type I vitamin D-resistant rickets, hypoparathyroidism, pseudohypoparathyroidism, and renal osteodystrophy and psoriasis.
Dietary intake of phosphorus is a determinant of 1,25-dihydroxy D3 production. Increases of 1,25-dihydroxy D relating to hypocalcemia are thought to be mediated through increased output of parathyroid hormone. Vitamin D is also influenced by thyroid status, estrogens, calcitonin, growth hormone, prolactin, insulin, and glucocorticoids.
The vitamin D endocrine system is linked to vitamin D-resistant rickets as well as classic vitamin D-deficient rickets and hypophosphatemic oncogenic rickets.
Because of the complex, multifactorial control of calcium balance, it is often useful to measure parathyroid hormone in conjunction with vitamin D.