LC-MS/MS reduces interference by high levels of 25(OH)D and its metabolites on measured 1,25(OH)2D.

BACKGROUND: High-dose vitamin D supplementation has been recommended as treatment to several conditions; however, potential side effects such as hypercalcemia should be considered, plus the fact that high levels of 25(OH)D may interfere with potential 1,25(OH)2D measurements. Our study compared two methods of measuring 1,25-dihydroxyvitamin D [1,25(OH)2D] in samples with 25-hydroxyvitamin D [25(OH)D] levels above 150 ng/mL (375 nmol/L). METHODS: We studied serum samples referred to 25(OH)D and 1,25(OH)2D quantification. The concentrations of 25(OH)D and 1,25(OH)2D were measured using DiaSorin chemiluminescent assays (CLIA) in 213 samples (CLIA group), whereas in 357 samples 25(OH)D and 1,25(OH)2D were measured by DiaSorin CLIA and liquid chromatography-tandem mass spectrometry (LC-MS/MS), respectively (CLIA + MS group). RESULTS: Median concentrations of 25(OH)D and 1,25(OH)2D in the CLIA group were 371 ng/mL (928 nmol/L, range 154-856 ng/mL) and 350 pg/mL (875 pmol/L, range 41-1280 pg/mL), respectively, and correlated significantly (Spearman correlation coefficient rs = 0.8469, P < 0.001). In the CLIA + MS group, the median concentrations of 25(OH)D and 1,25(OH)2D were, respectively, 344 ng/mL (860 nmol/L, range 152-756 ng/mL) and 56 pg/mL (140 pmol/L, range 17-151 pg/mL), and were not correlated (rs = 0.0218, P = 0.6811). No significant difference was found in calcium, creatinine, and PTH serum values between the groups. CONCLUSION: Methods for measuring 1,25(OH)2D in patients with high levels of 25(OH)D may be susceptible to interference by 25(OH)D and its metabolites and should be validated carefully. In such cases, measurement of 1,25(OH)2D using LC-MS/MS is preferred.

No association between vitamin D status and COVID-19 infection in São Paulo, Brazil

ABSTRACT In recent years the immunomodulatory actions of vitamin D, a steroid hormone, have been extensively studied. In 2020, due to the COVID-19 pandemic, the question arose as to 25(OH)D status would be related to susceptibility to SARS-CoV-2 infection, since several studies pointed out a higher prevalence and severity of the disease in populations with low levels of 25(OH)D. Thus, we investigated the 25(OH)D levels in adults "Detected" positive for SARS CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) test, and in negative controls, "not Detected", using the Fleury Group's examination database, in Sao Paulo, Brazil. Of a total of 14.692 people with recent assessments of 25(OH)D and RT-PCR tests for COVID-19, 2.345 were positive and 11.585 were negative for the infection. The groups did not differ in the percentage of men and women, or in the age distribution. There were no differences in the distribution of 25(OH)D between the two groups (p = 0.08); mean 25(OH)D of 28.8 ± 21.4 ng/mL and 29.6 ± 18.1 ng/mL, respectively. In the specific population studied, clinical, environmental, socioeconomic and cultural factors should have greater relevance than 25(OH)D in determining the susceptibility to COVID-19.

No association between vitamin D status and COVID-19 infection in São Paulo, Brazil.

In recent years the immunomodulatory actions of vitamin D, a steroid hormone, have been extensively studied. In 2020, due to the COVID-19 pandemic, the question arose as to 25(OH)D status would be related to susceptibility to SARS-CoV-2 infection, since several studies pointed out a higher prevalence and severity of the disease in populations with low levels of 25(OH)D. Thus, we investigated the 25(OH)D levels in adults "Detected" positive for SARS CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) test, and in negative controls, "not Detected", using the Fleury Group's examination database, in Sao Paulo, Brazil. Of a total of 14.692 people with recent assessments of 25(OH)D and RT-PCR tests for COVID-19, 2.345 were positive and 11.585 were negative for the infection. The groups did not differ in the percentage of men and women, or in the age distribution. There were no differences in the distribution of 25(OH)D between the two groups (p = 0.08); mean 25(OH)D of 28.8 ± 21.4 ng/mL and 29.6 ± 18.1 ng/mL, respectively. In the specific population studied, clinical, environmental, socioeconomic and cultural factors should have greater relevance than 25(OH)D in determining the susceptibility to COVID-19.

Valores falsamente elevados em ensaios diretos para a medida de hormônios esteróides no soro / Falsely elevated serum steroid hormone levels in direct assays

A dosagem sérica dos esteróides hormonais ainda se baseia no emprego de técnicas radioimunológicas, sendo que as metodologias clássicas empregam extraçäo e, se necessário, cromatografia preparativa. A necessidade de ensaios mais rápidos, simples e susceptíveis à automaçäo forçou o desenvolvimento de ensaios diretos de hormônios esteróides no soro, principalmente para os de maior interesse clínico como o estradiol, a testoterona e a progesterona. Neste trabalho descrevemos o encontro de resultados falsamente elevados com o emprego de ensaios diretos e automatizados para as medidas séricas de estradiol e de progesterona. a pré-extraçäo das amostras com solvente orgânico faz com que o fenômeno desapareça. Säo discutidas as possíveis razöes para este fenômeno e como conclusäo salientamos a necessidade de nova dosagem, após extraçäo, de amostras que apresentarem valores surpreendentemente elevados para a condiçäo clínica da paciente