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

We measured the serum concentration of 25-hydroxyvitamin D (25-OH-D) and 1,25-dihydroxyvitamin D (1,25-[OH]-D) 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)-D 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)-D 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)-D in target tissues for the hormone.