25-Hydroxyvitamin D (25OHD) is the major circulating form of vitamin D and the precursor of the active form (1,25-dihydroxyvitamin D). Because of its long half-life, 25OHD measurements are useful for assessing vitamin D status in patients. Vitamin D occurs in 2 forms: vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol). Vitamin D3 is obtained from foods of animal origin and from ultraviolet light-stimulated conversion of 7-dehydrocholesterol in the skin, whereas small amounts of vitamin D2 are obtained from foods of plant origin. Both forms of the vitamin are used to fortify various foods and in over-the-counter supplements, and vitamin D2 is used in a high potency (50,000 IU) formulation for treating severe vitamin D deficiency. Furthermore, both forms are metabolized to their respective 25OHD forms (ie, 25OHD3 and 25OHD2). Thus, analytical methods that can accurately quantitate both 25OHD forms are essential for diagnosis and monitoring patients with vitamin D disorders. Most current methods do not differentiate between the 2 forms: only total 25OHD concentrations are reported.
Additionally, some analytical methods may underestimate 25OHD concentration when significant amounts of 25OHD2 are present owing to diminished cross-reactivity.1 Other disadvantages to current methods include use of radioactive isotopes, method-to-method variation, and laboratory-to-laboratory variation.2 This liquid chromatography, tandem mass spectrometry (LC/MS/MS) method does not use radioisotopes and is sensitive and equally specific for both forms of 25OHD. Concentrations of each form are measured and reported independently. The reference range for total 25OHD (20-100 ng/mL) is based on 25OHD correlation with physiological parameters that include parathyroid hormone concentration and calcium absorption.4-8 The range is not based on the distribution of levels in an apparently healthy population. 25OHD2– and 25OHD3– specific reference ranges are not available. Decreased 25OHD concentrations are an indication of vitamin D deficiency and are associated with hypocalcemia, hypophosphatemia, and elevated alkaline phosphatase.
In addition to insufficient intake or production, disorders that are characterized by decreased absorption or excessive loss in the gastrointestinal tract, increased vitamin D metabolism, or impaired conversion of vitamin D to 25OHD can cause decreased 25OHD levels (Table). Elevated levels of 25OHD suggest vitamin D intoxication and distinguish this disorder from other hypercalcemia-causing disorders. Levels vary with exposure to sunlight, peaking in the summer months. 25-Hydroxyvitamin D Concentration in Various Disorders9-11 25OHD, 25-hydroxyvitamin D; * The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Comparison of commercially available 125I-based RIA methods for the determination of circulating 25-hydroxyvitamin D. Clin Chem. 2000;46:1657-1661. 2 Binkley N, Krueger D, Cowgill CS, et al. Assay variation confounds the diagnosis of hypovitaminosis D: a call for standardization.
J Clin Endocrinol Metab. 3 Koutkia P, Chen TC, Holick MF. Vitamin D intoxication associated with an over-the-counter supplement. N Engl J Med. 2001;345:66-67. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D. J Nutr. Vitamin D deficiency: what a pain it is. Mayo Clin Proc. 2003;78:1457-1459. 6 Lips P, Duong T, Oleksik A, et al. A global study of vitamin D status and parathyroid function in postmenopausal women with osteoporosis: baseline data from the multiple outcomes of raloxifene evaluation clinical trial. 7 Malabanan A, Veronikis IE, Holick MF. Redefining vitamin D insufficiency. 8 Plotnikoff GA, Quigley JM. Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific musculoskeletal pain. Mayo Clin Proc. 2003;78:1463-1470. 9 Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Larsen PR, Kronenberg HM, Melmed S, Polonsky KS, eds. Williams Textbook of Endocrinology.
10th ed. Philadelphia, PA: WB Saunders; 2003:1303-1371. 10 St-Arnaud R, Glorieux FH. Hereditary defects in vitamin D metabolism and action. In: DeGroot LJ, Jameson JL, et al, eds. Endocrinology. 4th ed. Philadelphia, PA: WB Saunders; 2001:1154-1168. 11 Goldring SR, Krane SM, Avioli LV. Disorders of calcification: osteomalacia and rickets. The page you were looking for doesn't exist. You may have mistyped the address or the page may have moved. QuestAssureD 25-Hydroxyvitamin D (D2, D3), LC/MS/MS QuestAssureD™ 25-Hydroxyvitamin D (D2, D3), LC/MS/MS Diagnose vitamin D deficiency or toxicity Monitor response to vitamin D2 or vitamin D3 supplementation An estimated 68% to 77% of patients have suboptimal (<30 ng/mL) levels of vitamin D.1,2 This important nutrient promotes skeletal health by enhancing the intestinal absorption of calcium and phosphorus. Deficiency is associated with bone diseases such as rickets, osteomalacia, and osteoporosis. Emerging evidence also suggests links to nonskeletal illnesses such as cancer (especially colorectal and breast), cardiovascular disease, and infectious and autoimmune diseases.3,4 Vitamin D toxicity, which manifests as hypercalcemia, hypercalciuria, or kidney stones, is rare but can result at serum levels above 150 ng/mL.4 Current guidelines recommend maintaining adequate vitamin D levels, with vitamin D supplementation if necessary, to maximize bone health and prevent bone disease.4-6 Accurate determination of vitamin D levels can help diagnose vitamin D deficiency
Vitamin D occurs in 2 forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is the main form and is produced in the skin in response toHowever, both forms can be obtained in relatively small amountsBoth are also available as over-the-counter supplements, but only vitamin D2 is available in high-dose prescription form in the United States.3 Vitamins D2 and D3 are metabolized to produce different 25-hydroxyvitamin D (25[OH]D) forms: 25(OH)D2 and 25(OH)D3; these metabolites are then converted to their corresponding active forms.4 The sum of 25(OH)D2 and 25(OH)D3 concentrations yields the total 25(OH)D level, which is the accepted standard for determining vitamin D status.4 The active form of vitamin D (1,25-dihydroxyvitamin D) is not useful for assessing vitamin D status, because its levels are often normal in patients with vitamin D deficiency.4Separate 25(OH)D2 and 25(OH)D3 measurements may help to differentiate the contributions of vitamin D2 and vitamin D3 to vitamin D status.
The LC/MS/MS method accurately and precisely measures 25(OH)D2 and 25(OH)D3 and sums these 2 analytes to obtain the total 25(OH)D concentration.7,8 In contrast, most immunoassay techniques do not differentiate the 2 forms. The QuestAssureD 25-Hydroxyvitamin D (D2, D3), LC/MS/MS test is useful for diagnosing vitamin D deficiency, monitoring response to vitamin D2 or D3 supplementation, and differentiating between vitamin D toxicity and other causes of hypercalcemia. Individuals with suspected vitamin D deficiency or who are at increased risk for vitamin D deficiency (eg, those with persistent, nonspecific musculoskeletal pain; those who are pregnant, lactating, dark-skinned, elderly, obese, or housebound; and those with conditions or taking medications associated with reduced 25[OH]D levels [see Individuals being treated with vitamin D2 or vitamin D3 supplementation Individuals with suspected toxicity (eg, those with hypercalcemia of obscure origin) For infants/toddlers <36 months old, use QuestAssureD for Infants, 25-Hydroxyvitamin D, LC/MS/MS (test code 91935).
Liquid chromatography–tandem mass spectrometry (LC/MS/MS) – Extraction via protein precipitation – Separation via high-performance liquid chromatography (HPLC) – Detection and quantitation via tandem mass spectrometry concentrations used to calculate total 25(OH)D levels Report includes concentrations of total 25(OH)D, 25(OH)D2, and 25(OH)D3 Analytical sensitivity: 4 ng/mL for 25(OH)D2 and for 25(OH)D3 Analytical specificity: no cross-reactivity with vitamin D2 or D3; 1-hydroxy and 1,25-dihydroxy forms of vitamin D2 or D3; Reportable range: 4-512 ng/mL for 25(OH)D2 and for 25(OH)D3; 4-1024 ng/mL for total 25(OH)D Abnormal 25(OH)D levels are associated with a range of conditions and medications (Table). reflect both endogenous production and exogenous sources such as diet or supplementation, whereas levels of reflect only exogenous sources and are detected in significant amounts only in response to intake of vitamin D2
supplements.7,8 There is no consensus about the optimal total level, which may vary with the assay used and functional outcome measured. However, many experts accept a range of 30-60 ng/mL Total 25(OH)D levels ≤20 ng/mL suggest vitamin D deficiency, while levels between 21 and 29 ng/mL suggest insufficiency.4 Expert opinions also vary about what constitutes 25(OH)D toxicity, with reported thresholds ranging from 50 ng/mL (125 nmol/L)1 to 150 ng/mL (374 nmol/L).4Effect of Various Disorders and Medications on Intestinal diseases causing excessive loss of vitamins D23 a Also called pseudo-vitamin D-deficiency rickets. b Also called hereditary vitamin D-resistant rickets. Lai JK, Lucas RM, Clements MS, et al. Assessing vitamin D status: pitfalls for the unwary. Mol Nutr Food Res. 2010;54:1062-1071. Ginde AA, Liu MC, Camargo CA, et al. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med. 2009;169:626-632.
N Engl J Med. 2007;357:266-281. Holick MF, Binkley NC, Heike A, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. Watts NB, Bilezikian JP, Camacho PM, et al. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the diagnosis and treatment of postmenopausal osteoporosis. Maunsell Z, Wright DJ, Rainbow SJ. Routine isotope-dilution liquid chromatography-tandem mass spectrometry assay for simultaneous measurement of the 25-hydroxy metabolites of vitamins D2 and D3. Herrmann M, Harwood T, Gaston-Parry O, et al. A new quantitative LC tandem mass spectrometry assay for serum 25-hydroxy vitamin D. Steroids. Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism.