Routine Biochemistry in Suspected Vitamin D Deficiency

Abstract

Vitamin D deficiency, which continues to be widespread amongst persons of Asian descent in the UK, is often detected from abnormal results on routine biochemistry. The aim of this study was to assess the frequency of abnormal results from routine baseline tests of serum calcium, phosphate, and alkaline phosphatase in patients who subsequently proved to have vitamin D deficiency and secondary hyperparathyroidism. A retrospective examination was undertaken to assess these baseline indices in a cohort of 84 such patients seen in Bradford-5 male; 80 of Asian descent; median age 46 years (range 16-82); serum 25-hydroxyvitamin D<10 microg/L; parathyroid hormone >54 ng/L. Calcium was normal in 55 patients (66%), phosphate in 68 (81%) and alkaline phosphatase in 24 (29%). In only 5 patients were all three indices outside the normal range. The median parathyroid hormone concentration was significantly greater in patients with abnormal routine biochemistry (145 [range 55-1662] ng/L) than in patients with normal routine biochemistry (88 [59-322] ng/L) but the median 25-hydroxyvitamin D levels did not differ (3.1 [1.3-9.9] and 3.0 [1.5-7.3] microg/L). Routine biochemistry was normal in 20% of cases. If routine biochemistry is relied upon to detect vitamin D deficiency and osteomalacia, a substantial minority of cases will be missed.

Seasonal variation of serum vitamin D and the effect of vitamin D supplementation in Irish community-dwelling older people

“…25 This strong effect of supplementation is consistent with observations from recent Irish studies [25,26]. In supplemented women, higher 25(OH)D was seen together with lower parathyroid hormone and alkaline phosphatase (Table 1), as clinically expected [27]. In the supplemented group, 25(OH)D seasonality was not detected, which may be due to: (i) the relatively small size of this group (i.e.…”

Modulation of Vitamin D Status and Dietary Calcium Affects Bone Mineral Density and Mineral Metabolism in Göttingen Minipigs

“…In the minipigs urinary calcium excretion, plasma PTH, and markers of bone turnover were found to have changed only slightly or nonsignificantly. This contrasts with what is typically found in patients, although with large variations [2, 21, 54, 55]. The hormonal state of the estrum cycle, which we did not assess or synchronize, could have contributed to the interindividual variations of bone markers or calcium metabolism-related hormones at the certain time points.…”

Frequency of vitamin D insufficiency in healthy children between 1 and 16 years of age in Turkey

“…A study conducted in the UK on adult patients, with 25(OH)D deficiency and secondary hyperparathyroidism shows that 20% of the subjects have normal routine biochemistry (Ca, P, and ALP). 47 Therefore it may be speculated that, if laboratory testing is confined to routine biochemistry, a substantial minority (20%) of these high-risk cases will have a false negative diagnosis. Another study, investigating two separate large cohorts totaling 1186 patients over a 4.5 year period, also showed that neither an elevated serum ALP, nor a low Ca or P are able to reliably detect hypovitaminosis D. 48 Therefore, normal ALP, Ca, P or PTH blood levels should not be interpreted as an indication of normal vitamin D status.…”