Elsevier

Bone

Volume 30, Issue 6, June 2002, Pages 886-890
Bone

Original article
Effect of feeding on bone turnover markers and its impact on biological variability of measurements

https://doi.org/10.1016/S8756-3282(02)00728-7Get rights and content

Abstract

Bone turnover markers are subject to day-to-day and within-day variability, which may influence clinical interpretation. We examined the effect of fasting vs. feeding on the concentration and between-day variability of several markers. Twenty healthy premenopausal women were studied on 10 consecutive weekdays. Subjects were studied either in the fasting (no breakfast) or fed (breakfast at 08:00 h) state on alternate days, and were randomized to begin either fasting or fed. Two hour urine collections were obtained each day between 08:00 h and 10:00 h, and blood samples were collected daily at 09:00 h. The N-telopeptide cross-link of type I collagen in urine (uNTX) and serum (sNTX), the C-telopeptide in urine (uCTX) and serum (sβCTX), and immunoreactive free deoxypyridinoline (uifDPD) in urine were measured as resorption markers. Procollagen type I N-terminal propeptide (PINP), osteocalcin (OC), and bone alkaline phosphatase (bone ALP) were measured as formation markers. All bone formation and resorption markers were significantly lower in the fed state with the exception of bone ALP. The magnitude of the decrease ranged from 3.8 ± 0.9% for PINP (p < 0.0001) to 17.8 ± 2.6% (p < 0.0001) for sβCTX. Measurement variability was partitioned into analytical variability based on replicate assays (CVa) and within-subject variability (CVi). The CVi was greater (p < 0.05) for some markers in the fasting state (uifDPD, uNTX, and sNTX) but greater in the fed state for other markers (OC and sβCTX). In conclusion, the clinical impact of feeding vs. fasting is small with the exception of sβCTX; however, in clinical practice, collection of samples in the fasting state may be necessary to minimize the unpredictable effects of feeding. The mechanism of the acute effect of feeding on bone turnover remains uncertain.

Introduction

Biochemical markers of bone turnover may be of value to predict the rate of bone loss and the risk of osteoporotic fracture and to monitor treatment response in metabolic bone diseases, particularly osteoporosis.11 Bone turnover markers are subject to biological variability, which may influence clinical interpretation. These factors include the effects of circadian rhythms, dietary calcium intake, growth, aging, sex hormone status, gender, and for urine-based markers the requirement to correct for urine dilution using creatinine concentration.13 Day-to-day variability (coefficient of variation [CV]) levels of 5%–13% for formation markers and 6%–34% for resorption markers have been observed under clinical research conditions in several studies.13 In clinical practice, it is important to minimize the impact of different sources of biological variability.11

There is increasing evidence that a variety of dietary factors may result in acute changes in bone turnover. This is a source of biological variability, although the potential importance of acute changes in dietary intake has never been systematically examined. Thus, calcium supplements may suppress resorption within a few hours5 and recent studies have shown that acute ingestion of glucose may decrease bone resorption.3, 4 Other dietary components may induce analytical artifacts; for example, dietary intake of gelatine may increase excretion of hydroxyproline, but not urinary pyridinolines.9 In addition, the circadian rhythm of bone turnover is attenuated by food intake throughout the 24 h cycle.7, 21

Standardization of dietary intake prior to sampling could improve the performance of these measurements in clinical practice. First, standardization of sampling conditions could reduce measurement variability. Although it has been suggested11 that all markers of bone turnover should be assessed in the fasting state, there is as yet little evidence to support this assertion. Second, recent dietary intake may influence the reference range.

The aims of this study were to determine the effect of fasting or feeding on: (1) the concentration of markers of bone turnover; (2) analytical and within-subject variability; and (3) the clinical interpretation of results. A wide spectrum of analytes are examined to establish if changes in diet represent an important feature of biological variability for commercial assays currently available for use in research and clinical practice.

Section snippets

Subjects

Twenty healthy premenopausal women (mean age of 33 years, range 21–45 years) were recruited from the staff at the Northern General Hospital, Sheffield. All participants completed a lifestyle, general health, and osteoporosis risk factor questionnaire. Women were excluded if they had any disease known to affect bone metabolism, had sustained a fracture during the preceding 12 months, or were taking any medication known to affect bone metabolism apart from an oral contraceptive (n = 9). Four

Results

All bone formation and resorption markers were significantly lower in the fed state (Table 1) with the exception of bone ALP. Mean percentage differences between the fasting and fed state for individual subjects are shown in (Figure 2). The magnitude of the decrease with feeding ranged from 3.8 ± 0.9% for PINP (p < 0.0001) to 17.8 ± 2.6% (p < 0.0001) for sβCTX. The decrease was observed for both serum markers (range 3.8%–17.8%) and urine markers (range 7.0%–7.9%). The decrease in formation

Discussion

There is increasing evidence that food intake may result in acute changes in bone turnover. A marked circadian rhythm has been observed for bone turnover markers.15, 22 Fasting attenuated the circadian rhythm observed for sCTX and uCTX, but not for OC, which suggests dietary changes may partially contribute to the circadian rhythm.7, 21 Nonfasting samples have frequently been collected during clinical studies,2, 11, 19, 27 but the importance of feeding for different markers remains unknown. The

Acknowledgements

The authors thank all the volunteers from the Osteoporosis Centre and the Department of Orthopaedics for participating in the study. We also thank Debbie Swindell, Joanne Li, and Alison Eagleton for their assistance. Roche Diagnostics, Penzberg, Germany, provided an unrestricted grant toward the cost of the bone turnover markers assays.

References (27)

  • M. Horowitz et al.

    Oral calcium suppresses biochemical markers of bone resorption in normal men

    Am J Clin Nutr

    (1994)
  • R.J. Walton et al.

    An estimate of the turnover rate of bone-derived plasma alkaline phosphatase in Paget’s disease

    Clin Chim Acta

    (1975)
  • T. Alstrom et al.

    Establishing reference values from adultsRecommendation on procedures for the preparation of individuals, collection of blood, and handling and storage of specimens. Committee on Reference Values of the Scandinavian Society for Clinical Chemistry

    Scand J Clin Lab Invest

    (1993)
  • D.C. Bauer et al.

    Biochemical markers of bone turnover and prediction of hip bone loss in older womenThe study of osteoporotic fractures

    J Bone Miner Res

    (1999)
  • N.H. Bjarnason et al.

    Acute insulin stimulation reduces bone resorption

    J Bone Miner Res

    (2000)
  • N.H. Bjarnason et al.

    Acute regulation of bone resorption is controlled by glucose metabolism

    J Bone Miner Res

    (2000)
  • A. Blumsohn et al.

    The effect of calcium supplementation on the circadian rhythm of bone resorption

    J Clin Endocrinol Metab

    (1994)
  • M.A. Braga de Castro et al.

    Monitoring alendronate therapy for osteoporosis

    J Bone Miner Res

    (1999)
  • S. Christgau

    Circadian variation in serum CrossLaps concentration is reduced in fasting individuals

    Clin Chem

    (2000)
  • A. Colwell et al.

    The renal clearance of free and conjugated pyridinium cross-links of collagen

    J Bone Miner Res

    (1996)
  • A. Colwell et al.

    Factors affecting the assay of urinary 3-hydroxy pyridinium crosslinks of collagen as markers of bone resorption

    Eur J Clin Invest

    (1993)
  • A.M. Cooper et al.

    Fasting and post-prandial splanchnic blood flow is reduced by a somatostatin analogue (octreotide) in man

    Clin Sci (Colch)

    (1991)
  • P.D. Delmas et al.

    The use of biochemical markers of bone turnover in osteoporosis. Committee of Scientific Advisors of the International Osteoporosis Foundation

    Osteopor Int

    (2000)
  • Cited by (237)

    • Impact of radiotherapy on bone health in women with rectal cancer – A prospective cohort study

      2022, European Journal of Surgical Oncology
      Citation Excerpt :

      The blood samples were drawn between 08.00 and 10.00 a.m., as the bone resorption marker CTX shows diurnal variation, with the highest concentrations early in the morning. Samples were drawn after an overnight fast since some bone markers, particularly CTX, are suppressed by feeding [29,30]. Serum sclerostin, CTX, BALP, intact PINP, oestradiol, and testosterone were analysed.

    • Alliances of the gut and bone axis

      2022, Seminars in Cell and Developmental Biology
    View all citing articles on Scopus
    View full text