Elsevier

Gait & Posture

Volume 59, January 2018, Pages 71-75
Gait & Posture

Full length article
Vitamin D and parathyroid hormone are associated with gait instability and poor balance performance in mid-age to older aged women

https://doi.org/10.1016/j.gaitpost.2017.09.036Get rights and content

Highlights

  • Both PTH and vitamin D (25-OHD) are significantly associated with fall-related measures in healthy, mid to older aged women.

  • Serum levels of 25-OHD and PTH are associated with the double support duration of gait in women over 47 years.

  • 25-OHD levels are significantly associated with dynamic balance/the step test in this cohort.

  • In women aged over 47, it is important to consider levels of PTH and 25-OHD in relation to gait and balance performance.

Abstract

Context

Vitamin D status and parathyroid hormone (PTH) levels influence the risk of accidental falls in older people, but the mechanisms underlying this effect remain unclear.

Objective

Investigate the relationship between circulating PTH and 25 hydroxyvitamin D (25-OHD) levels and clinical tests of gait stability and balance as physical fall risk factors. We hypothesized that high levels of PTH and low 25-OHD levels would be significantly associated with gait stability and decreased balance performance.

Design

Observational cohort study.

Setting

Australian community.

Participants

119 healthy, ambulatory female twin adults aged 47–80 years residing in Victoria, Australia.

Outcome measures

Serum PTH and 25-OHD levels with clinical tests of gait stability [double support duration (DSD)] and dynamic balance (Step Test). Associations were investigated by regression analysis and by comparing groups divided by tertiles of PTH (<3.5, 3.5–4.9, >4.9 pmol/L) and 25-OHD (<53, 53–75, >75 nmol/L) using analysis of variance.

Results

Serum PTH was associated positively with DSD, with an increase of 10.6–15.7% when the mid and highest PTH tertiles were compared to the lowest tertile (p < 0.025) when 25-OHD was included in the regression analysis. 25-OHD was significantly associated with DSD (greater by 10.6–11.1% when lowest and mid-tertiles compared with the highest 25-OHD tertile) (p < 0.025) and dynamic balance (better performance by 12.6% in the highest compared with the lowest 25OHD tertile) (p < 0.025).

Conclusion

These findings reveal an important new relationship between parathyroid hormone and gait stability parameters and add to understanding of the role of 25-OHD in motor control of gait and dynamic balance in community-dwelling women across a wide age span.

Introduction

Specific hormones play an important role in musculoskeletal health and in fall and fracture prevention in older adults. Poor vitamin D status (as determined by low serum 25 hydroxyvitamin D (25-OHD) concentration) and high levels of parathyroid hormone (PTH) have been implicated in sarcopenia and loss of muscle strength [1], and may also influence other fall risk factors such as motor control of gait and dynamic balance control. The inter-relationship between PTH, 25-OHD levels and gait parameters is currently unclear [2]. Although supplementation with vitamin D has been shown to improve leg muscle strength [3], postural sway and functional tasks (for example, the Timed Up and Go test), the impact of supplementation on specific balance tasks is less clear [2]. Either in association with low levels of vitamin D or independently, the role of PTH in these fall risks factors remains less clear [4].

Vitamin D levels and accidental falling have been the subject of considerable investigation, largely in frail older people, producing non-linear and conflicting results with differences depending on the functional status of the populations investigated. Current theory supports a relationship which is U-shaped, with both very high and very low levels related to increased rates of falls [5]. Mechanisms for the increased fall rates at both ends of the curve may be different; for higher functioning people, high levels of physical activity and ‘risk’ associated with some activities may account for this higher fall rate at higher levels of 25-OHD. At the older and frailer end of the spectrum, the lower levels of 25-OHD associated with falling [5] may relate to reduced strength and muscle mass [1]. However, the roles of 25-OHD and PTH in neural control are less clear.

There is considerable debate as to the level of 25-OHD that maximally suppresses PTH; it is estimated to vary between 25 and 122 nmol/L [6], [7]. More importantly, there is evidence that, in an older cohort, increases in PTH may independently play a role in physiological functioning of muscle and neural tissue, but this area has not been well investigated across the life-course. PTH has been shown to relate to handgrip strength and not balance [8], and more recently the same authors found no relationship between PTH and mobility limitations [9]. While the PTH response to low levels of 25-OHD appears to be a good marker of functional outcomes [10], and a predictor of morbidity and mortality [11], there is increasing evidence that PTH may act independently of vitamin D in adverse health outcomes [12] [13]. For example, PTH predicts mortality independently of vitamin D levels in community-dwelling older adults [14] and in frail older adults [15]. Recently, PTH and not 25-OHD have been found to be associated with gait stability parameters in an older cohort (mean age 81 years) [16].

In relation to falls, serum PTH levels predict time to first fall in a frail population [17]. Higher PTH and lower 25-OHD were reported in long-term care or assisted-living facility residents who had fallen [18]. While PTH was significantly higher in the group who had fallen (mean PTH (SD): fallers = 3.55 ng/L (2.44) vs. non-fallers = 3.32 ng/L (2.05); p = 0.041), no association between 25-OHD and fall rates was found once data were adjusted for high PTH levels. This reinforces the importance of PTH, and suggests that low levels of 25-OHD may increase falls risk only when combined with elevated levels of PTH in a frail older population [4].

The relationship between PTH, vitamin D and falls in healthier mid-age to older people remains less investigated than in frail groups, and it is important to also examine relationships between PTH levels specifically among vitamin D replete adults to determine whether independent action of this hormone on fall risk is present. Thus, the purpose of this study was to investigate the relationship between PTH and 25-OHD levels and clinical tests of gait stability and dynamic balance with respect to their role as physical fall risk factors in adults over 45 years old. It was hypothesized that high levels of PTH and low levels of serum 25-OHD would be significantly associated with poorer gait and dynamic balance performance.

Section snippets

Study participants

Participants who were female twins over the age of 45 years who had previously participated in heritability studies recruited from the Australian Twin Registry (ATR) and Twin Research Program at the Royal Melbourne Hospital (Melbourne, Victoria, Australia) were invited to take part in this study. Those with major musculoskeletal or any neurological disorders or without a good understanding of the English language were excluded. Screening was undertaken to ensure that no neurological balance

Results

Of the 252 women approached (126 pairs) to participate in the study, 122 participants were recruited (61 pairs, 48% response rate). Three participants were unable to supply a blood sample, giving a total of 119 women between the ages of 47 and 80 (mean 59.4 ± 8.2) years with a mean BMI of 26.3 (SD 4.6). All participants were living in the State of Victoria, Australia, with the majority (58.0%) of the sample living in Melbourne (38° South). Eighty-six percent of participants regarded their general

Discussion

The main objective of this study was to determine whether levels of PTH and 25-OHD were associated with performance on gait and balance measures in apparently-healthy older women with no neurological balance disorder. In this cohort, it was found that both PTH and 25-OHD were significantly associated with gait stability (DSD), and 25-OHD was significantly associated with dynamic balance performance. Findings from this study suggest that higher PTH was associated with poorer gait performance

Conflict of interest

We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed.

Acknowledgements

Funding received by the co-authors that part funded this project include;

Cohort studies of bone density change in female twins. NH&MRC Research Project Grant. JD Wark, CA Nowson, JL Hopper. ($464,953)

Cohort studies of bone density change in female twins. VicHealth Research Program. JD Wark, CA Nowson, JL Hopper. ($86,036)

A study of the heritability of balance using a cohort of postmenopausal twins. Rebecca L. Cooper Medical Research Foundation. JD Wark, AM Cassano, K Hill. (8000)

A study of the

References (36)

  • M.E. Ooms et al.

    Vitamin D status and sex hormone binding globulin: determinants of bone turnover and bone mineral density in elderly women

    J. Bone Miner. Res.

    (1995)
  • D.K. Houston et al.

    Association between vitamin D status and physical performance: the InCHIANTI study

    J. Gerontol. Ser. A: Biol. Sci. Med. Sci.

    (2007)
  • D.K. Houston et al.

    Low 25-hydroxyvitamin D predicts the onset of mobility limitation and disability in community-dwelling older adults: the Health ABC Study

    J. Gerontol. Ser. A: Biol. Sci. Med. Sci.

    (2012)
  • T. Alarcón et al.

    Parathyroid hormone response to two levels of vitamin D deficiency is associated with high risk of medical problems during hospitalization in patients with hip fracture

    J. Endocrinol. Invest.

    (2015)
  • A.N. Peiris et al.

    Secondary hyperparathyroidism: benign bystander or culpable contributor to adverse health outcomes

    South. Med. J.

    (2012)
  • A. Fisher et al.

    Elevated serum PTH is independently associated with poor outcomes in older patients with hip fracture and vitamin D inadequacy

    Calcif. Tissue Int.

    (2009)
  • D.S. Domiciano et al.

    Bone mineral density and parathyroid hormone as independent risk factors for mortality in community-dwelling older adults: a population-based prospective cohort study in Brazil. the São paulo ageing & health (SPAH) study

    J. Bone Miner. Res.

    (2016)
  • P.N. Sambrook et al.

    Serum parathyroid hormone is associated with increased mortality independent of 25-hydroxy Vitamin D status, bone mass, and renal function in the frail and very old: a cohort study

    J. Clin. Endocrinol. Metab.

    (2004)
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