Measuring vitamin D levels: surrogates are insufficient. Issue 1 (31st October 2014)

• Record Type: Journal Article
• Authors: Heald, A. H.; Anderson, S. G.; Scargill, J. J.; Short, A. D.; Holland, D.; Livingston, M.; Fryer, A. A.; Donn, R. P.
• Is Part Of: International journal of clinical practice. Volume 69:Issue 1(2015)
• Page Start: 131
• Page End: 135
• Publication Date: 2014-10-31
• Subjects: Clinical medicine -- Periodicals; Medicine -- Periodicals; 610.5
• DOI: 10.1111/ijcp.12505
• Languages: English
• ISSNs: 1368-5031

Abstract

<abstract abstract-type="main" id="ijcp12505-abs-0001"> <title>Summary</title> <sec id="ijcp12505-sec-0001" sec-type="section"> <title>Aims</title> <p>With the increasing evidence of adverse consequences because of low vitamin D levels on health demand for vitamin D, screening is increasing.</p> <p>The objective of the study was to assess whether parathyroid hormone (PTH) levels/bone profile is sufficient to identify patients with vitamin D insufficiency or deficiency, or whether vitamin D should be measured directly.</p> </sec> <sec id="ijcp12505-sec-0002" sec-type="section"> <title>Methodology</title> <p>A total of 1560 serum specimens, with requests for 25‐hydroxyvitamin D (25‐OH vitamin D), calcium, phosphate, alkaline phosphatase (ALP), creatinine and PTH on the same sample were analysed at Salford Royal Hospital from November 2010 to November 2012.</p> </sec> <sec id="ijcp12505-sec-0003" sec-type="section"> <title>Results</title> <p>The prevalence of total vitamin D insufficiency or deficiency (defined as total 25‐OH vitamin D < 50 nmol/l) was 62.9% (981/1560) overall, with males having higher proportions (67.2 vs. 59.3 per cent; <bold>χ</bold><sup>2</sup> = 8.78, p = 0.003). There was no overall trend in mean serum adjusted calcium across categories of 25‐OH vitamin D status but mean serum phosphate was significantly lower (<italic>F</italic> = 6.53, p < 0.0001) in patients with a 25‐OH vitamin D level < 50 nmol/l. However in patients with vitamin D deficiency, a significant proportion had PTH, calcium, phosphate and alkaline phosphatase levels within the laboratory normal range. Even at a 25‐OH vitamin D < 10 nmol/l, 71.6% had a normal PTH, 89.8% had normal serum calcium levels, 84.9% had normal phosphate levels and 81.6% had normal serum ALP.</p> </sec> <sec id="ijcp12505-sec-0004" sec-type="section"> <title>Conclusions</title> <p>Therefore, despite the costs associated with the measurement of vitamin D, our findings show that no surrogate is adequate for screening for vitamin D deficiency.</p> </sec> </abstract>