Vitamin D deficiency may give rise to a series of health issues, including osteoporosis, rickets, osteomalacia, and even have an impact on cardiovascular, immune, and metabolic functions ^[1]. Additionally, for special groups such as pregnant women, infants, and the elderly, inadequate vitamin D can increase the risks of fractures, premature birth, and other complications. Therefore, proper supplementation of vitamin D plays a crucial role in maintaining bone health, promoting immune function, and preventing chronic diseases.

Who is at high risk for vitamin D deficiency:

Special groups - Pregnant and lactating women, elderly individuals with a history of falls and/or non-traumatic fractures, people with insufficient sun exposure (indoor workers, night shift workers), obese children and adults (BMI ≥ 30 kg/m²), and those who have undergone bariatric surgery.

People with diseases - Rickets, osteomalacia, osteoporosis, hyperparathyroidism, chronic kidney disease, liver failure, small intestinal malabsorption syndrome, acute/chronic diarrhea, steatorrhea, inflammatory bowel diseases (Crohn's disease, ulcerative colitis), radiation enteritis, lymphoma, granulomatous diseases: sarcoidosis, tuberculosis, AIDS, etc.

People taking certain medications -

○ Antiepileptic drugs: phenytoin, phenobarbital, etc.;

○ Glucocorticoids: prednisone, etc.;

○ Antituberculosis drugs: rifampicin, etc.;

○ Azole antifungal drugs: ketoconazole, etc.;

○ Some lipid-regulating drugs: cholestyramine (Questran), etc.

How to determine if one is deficient in vitamin D?

The measurement of serum 25(OH)D levels is widely regarded as the most reasonable indicator to reflect the status of vitamin D. Currently, the reference values for serum 25(OH)D recognized by the majority of international institutions and experts are as shown in the following table:

Table 1-Reference range of serum 25(OH)D ^[3]

Prevention of Vitamin D Deficiency

01 - General Measures for Preventing Vitamin D Deficiency

Increasing sun exposure and intake of foods rich in vitamin D are economical and effective approaches to prevent vitamin D deficiency or insufficiency. During summer and autumn, it is advisable to expose oneself actively to sunlight, with the recommended average outdoor activity time being 1 to 2 hours per day ^[4]. When sun exposure is lacking, supplementation with either vitamin D2 or vitamin D3 is suggested, as there is no significant difference in efficacy and safety between the two ^[5].

02 - Vitamin D Supplementation Recommendations for High-Risk Groups

Table 2-Vitamin D Supplementation Recommendations for High-Risk Groups of Vitamin D Deficiency ^[3]

03 - Vitamin D Supplementation Recommendations for Special Populations

It is recommended that pregnant and lactating women supplement with 1500 to 2000 IU of vitamin D per day, while those at a high risk of vitamin D deficiency can tolerate up to 100,000 IU per day. It is proposed that obese children and adults, as well as those taking anticonvulsants, glucocorticoids, antifungal drugs, and antiretroviral drugs, require at least 2 to 3 times the amount of vitamin D needed by their age group to meet their requirements ^[3].

For the prevention and treatment of vitamin D deficiency, it is recommended to use regular vitamin D2 or D3 preparations. The use of a single large dose is not recommended. Nor is it recommended to correct vitamin D deficiency with active vitamin D or its analogues.

04 - Recommended Dosage for the Treatment of Vitamin D Deficiency ^[2]

The Dilemma and Solution of Vitamin D Detection

After supplementing with vitamin D2 or D3, regular detection of vitamin D levels in the body is crucial for evaluating therapeutic efficacy and adjusting dosages. However, the current gold standard, liquid chromatography-tandem mass spectrometry (LC-MS/MS), although highly accurate, has low throughput, is operationally complex, and cannot provide results on the same day, causing significant inconvenience for clinical practice and laboratory testing. Meanwhile, the mainstream chemiluminescence immunoassay competition methods have issues with low accuracy when detecting small molecules, particularly when measuring 25(OH)D2, and show poor consistency with the results from mass spectrometry ^[6].

Figure 1 Comparison of Results from Five Chemiluminescence Immunoassay Competition Methods and LC-MS/MS for 25(OH)D2 Detection

To address this issue, Snibe has innovatively adopted the small molecule sandwich method to detect 25(OH)D, which can circumvent the inherent detection flaws of the competitive method and accurately measure the level of 25(OH)D in the body. Snibe has collaborated with well-known domestic clinical institutions to include 1,309 samples in a methodological comparison of 25(OH)D, with a correlation coefficient of 0.97, indicating good consistency with the results of the mass spectrometry method. Meanwhile, a separate analysis was conducted on 281 samples containing 25(OH)D2, with a correlation coefficient of 0.95. These data demonstrate that the small molecule sandwich method can overcome the limitations of the traditional competitive method and simultaneously detect 25(OH)D2 and 25(OH)D3, with excellent detection performance.

Figure 2-Comparison of 25(OH)D results between Snibe and LC-MS/MS detection

(A) 25(OH)D samples; (B) Samples containing 25(OH)D2;

In addition, considering that people with osteoporosis, tumors, chronic kidney disease, and hemodialysis are high-risk groups for vitamin D deficiency, to evaluate the impact of different patient groups on the detection of 25(OH)D by the small molecule sandwich method, a total of 323 patients from both domestic and international with different diseases were included for testing. The results showed that the correlation coefficient between the two methods was as high as 0.948, indicating that the small molecule sandwich method has high accuracy in the detection of vitamin D in various populations.

Figure 3-Comparison of the results of vitamin D detection in different patient groups by Snibe and LC-MS/MS

The prevention and treatment of vitamin D deficiency rely on precise detection methods. Snibe's small molecule sandwich method can effectively solve the problem of inaccurate detection of 25(OH)D2, facilitating precise diagnosis and treatment of vitamin D deficiency-related diseases in clinical practice.

References:

[1] Nonclassic actions of vitamin D [J]. J Clin Endocrinol Metab, 2009, 94:26-34.

[2] Consensus on the Clinical Application of Vitamin D and Its Analogues [J]. Chinese Journal of Osteoporosis and Bone Mineral Research, 2018, 11(01): 1-19.

[3] Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline[J]. J Clin Endocrinol Metab, 2011, 96:1911-1930.

[4] Expert Consensus on the Clinical Application of Vitamin A and Vitamin D in Chinese Children [J]. Chinese Journal of Child Health Care, 2021, 29(01): 110-116.

[5] Vitamin D₂is as effective as vitamin D₃in maintainingcirculating concentrations of 25-hydroxyvitamin D[J]. J Clin Endocrinol Metab, 2008, 93:677-681.

[6] Comparison of Five Automated Immunological Methods and Liquid Chromatography-Tandem Mass Spectrometry for the Determination of 25-Hydroxyvitamin D. Chinese Journal of Laboratory Medicine, 2015, 38: 7.