Details

Autor(en) / Beteiligte

• Dovio, A.
• Generali, D.
• Tampellini, M.
• Berruti, A.
• Tedoldi, S.
• Torta, M.
• Bonardi, S.
• Tucci, M.
• Allevi, G.
• Aguggini, S.
• Bottini, A.
• Dogliotti, L.
• Angeli, A.

Titel

Variations along the 24-hour cycle of circulating osteoprotegerin and soluble RANKL: a rhythmometric analysis

Ist Teil von

• Osteoporosis international, 2008, Vol.19 (1), p.113-117

Ort / Verlag

London: Springer-Verlag

Erscheinungsjahr

2008

Quelle

MEDLINE

Beschreibungen/Notizen

• Summary The variability of serum osteoprotegerin (OPG) and soluble RANKL (sRANKL) along the 24-h cycle was assessed in 20 healthy women. No rhythmic variations of serum OPG, sRANKL or sRANKL/OPG ratio were detected as a group phenomenon. Timing of sampling is unlikely to influence the results of measurements of circulating OPG and sRANKL. Introduction Physiological bone turnover shows diurnal variations. The aim of the study was to assess variability of OPG and sRANKL serum levels along the 24-h cycle. Methods Blood was collected from 20 healthy women (median age 31 years, range 25–65 years) at 4-h intervals between 08:00 and 24:00 and at 2-h intervals between 24:00 and 08:00. Serum albumin, cortisol, osteocalcin (OC), C-terminal telopeptide of type I collagen (CTX), OPG and total sRANKL were measured. Temporal variations were assessed by the COSINOR model. Results Circadian rhythms of cortisol and albumin documented a normal synchronization within the circadian structure. Serum OC and CTX showed rhythmic variations, peaking at night-time. Rhythmic variations of serum OPG, sRANKL and sRANKL/OPG ratio were not detected as a group phenomenon. On an individual basis, rhythmic changes were detected in ten patients for OPG and eight patients for sRANKL, with very small amplitudes and heterogeneous acrophases. Conclusions The absence of consistent rhythmic variations of circulating OPG and sRANKL levels may reflect the absence of rhythmic variations of their expression in the bone microenvironment. Were this the case, the nocturnal rise of bone resorption should be accounted for by different, not RANKL/OPG-mediated factors. Since circulating OPG and sRANKL may derive from sources other than bone, rhythmicity could be masked by non-rhythmic or non-synchronized rhythmic expression in these sources. Timing of sampling is unlikely to influence the results of measurements of circulating OPG and sRANKL.