Another strength is the simultaneous determination of calcium, phosphate and PTH, allowing a brief assessment of the biological impact of hypovitaminosis D. Finally, although gold standard is liquid chromatography-tandem mass spectrometry, our technique of vitamin D measurement by chemiluminescent immunoassay is a good method for assessing 25(OH)D, as subject to small intra- and interassay coefficient of variations [24]. This evidence concerns the gene PTH and rickets.