Vitamin D, parathyroid hormone levels and bone mineral density in community-dwelling older women: The Rancho Bernardo Study

Vitamin D deficiency in Spain: a population-based cohort study

“…However, with the simultaneous measurement of 25-hydroxyvitamin D and iPTH, the validation of this objective is far from being satisfactorily achieved. Nonetheless, our results suggest, similar to others (Heaney, 2000;von Mühlen et al, 2005), that values of 25-hydroxyvitamin D above 30 ng/ml could prevent secondary hyperparathyroidism in most persons. Even so, numerous gaps still remain concerning the best criterion for the diagnosis of vitamin D deficiency.…”

“…The fall in 25-hydroxyvitamin D with age seen in this study seems consistent with the findings of others (Chapuy et al, 1997;Jacques et al, 1997;Malabanan et al, 1998;Mezquita-Raya et al, 2001;Vieth et al, 2003;von Mühlen et al, 2005;Arabi et al, 2010), though not all (Harris et al, 2000;Tangpricha et al, 2002;Christensen et al, 2010). The rise in iPTH levels with age seems to occur whatever the levels of 25-hydroxyvitamin D and does not seem to be explained just by the vitamin D3 nutritional status.…”

“…On the other hand, the variability in iPTH with seasonal climate changes was lower than that for 25-hydroxyvitamin D, as occurred elsewhere (von Mühlen et al, 2005), and the correlation between iPTH and 25-hydroxyvitamin D was less obvious in spring and summer (data not shown), as in other studies (Maeda et al, 2010), probably related with the different turnover of vitamin D3 and iPTH at a time when the production of vitamin D3 in the skin is greater. In general, most studies assume that iPTH reaches a plateau when 25-hydroxyvitamin D values reach a particular concentration (Chapuy et al, 1997;Khosla et al, 1997;Malabanan et al, 1998;Thomas et al, 1998;Leboff et al, 1999;von Mühlen et al, 2005). This observation has led to the use of iPTH levels as a biological marker for the nutritional status of vitamin D (Holick, 2007).…”

“…In the study by Vieth et al (2003), the correlation between age and creatinine was just seen in the older persons, the correlation between 25-hydroxyvitamin D and creatinine only in the younger persons and the change in iPTH correlated with the creatinine only in the older persons, not the younger. von Mühlen et al (2005) on the other hand, found no correlation between creatinine clearance and levels of iPTH or vitamin D. Although most reports have documented a vitamin D deficiency in uremic patients especially due to chronic kidney disease-related comorbidities (LaClair et al, 2005;Mehrotra et al, 2008), other have not (Craver et al, 2007). Indeed, 25-hydroxyvitamin D levels remained unchanged and levels of 1,25-dihydroxyvitamin D fell as the kidney disease progressed.…”

“…There is a well defined negative correlation between iPTH and 25-hydroxyvitamin D (Chapuy et al, 1997;Khosla et al, 1997;Malabanan et al, 1998;Thomas et al, 1998;Leboff et al, 1999;Vieth et al, 2003;von Mühlen et al, 2005;Christensen et al, 2010;Ho-Pham et al, 2010), but the features of this relation and the influence of age have not been fully defined. iPTH seems to be higher in older people than in young people (Arabi et al, 2010;Christensen et al, 2010), but it has been suggested that the relationship between Vitamin D and iPTH is different in older persons compared with young persons, such that for the same levels of 25-hydroxyvitamin D older persons could have higher iPTH (Vieth et al, 2003;Arabi et al, 2010).…”