Serum concentrations of 1,25‐dihydroxyvitamin D 3 in Platyrrhini and Catarrhini: A phylogenetic appraisal

We measured the serum concentration of 25‐hydroxyvitamin D 3 (25‐OH‐D 3 ) and 1,25‐dihydroxyvitamin D 3 (1,25‐[OH] 2 ‐D 3 ) in 23 different Platyrrhines from four different genera and in 21 Catarrhines from six different genera in residence at the Los Angeles Zoo. The mean (±S.E.) serum concentration of 1,25‐(OH) 2 ‐D 3 was significantly greater in Platyrrhines (810 ± 119 pg/ml) than in Catarrhines (61 ± 5 pg/ml), suggesting that high circulating concentrations of the active vitamin D hormone were a characteristic of New World primates in both the Cebidae and Callitrichidae family. This increase in the serum concentration of 1,25‐(OH) 2 ‐D 3 is probably an adaptational response on the part of Platyrrhini to offset a relative decrease in the concentration of specific receptor for 1,25‐(OH) 2 ‐D 3 in target tissues for the hormone.