Research Article: Renal osteodystrophy in the obesity era: Is metabolic syndrome relevant?

Date Published: July 18, 2017

Publisher: Public Library of Science

Author(s): Janaina Da Silva Martins, João Henrique Castro, Nestor A. Sainz Rueda, Luciene Machado dos Reis, Vanda Jorgetti, Rosa Maria Affonso Moysés, Jacqueline Teixeira Caramori, Mario Cozzolino.

http://doi.org/10.1371/journal.pone.0180387

Abstract

Observational studies have shown a beneficial effect of obesity on bone health; however, most of those studies were not based on bone biopsies. Metabolic syndrome (MetS) could have an effect on bone remodeling. However, there are no data on the effects of MetS in the presence of renal osteodystrophy.

The aim of this study was to investigate associations between MetS and renal osteodystrophy using the bone histomorphometric turnover-mineralization-volume (TMV) classification.

This observational cross-sectional study included 55 hemodialysis patients (28 women/27 men) who were evaluated for MetS and bone histomorphometry. Biochemical parameters included calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, free serum leptin, fibroblast growth factor 23 (FGF23), intact osteocalcin, sclerostin (Scl), glucose, insulin, and thyroid hormones. Robust models of multivariate linear regressions were used for the statistical analyses.

Females had higher iPTH levels (1,143 vs. 358, p = 0.02). Patients with normal bone volume (BV/TV) had a higher prevalence of MetS (73.6% vs. 41.7%, p = 0.02) and higher serum phosphorus, C-terminal FGF23 and insulin levels. The multivariate regression analysis showed that low-density lipoprotein cholesterol (LDL) was positively correlated with bone formation rate (BFR/BS) and negatively associated with mineralization lag time. Bone volume was negatively associated with age but positively associated with MetS. Body mass index (BMI) was not correlated with any of the bone histomorphometric parameters.

Our results suggest that MetS is not a risk factor for low bone volume in hemodialysis patients. Furthermore, BMI alone was not related to bone volume in this population.

Partial Text

The prevalence of obesity more than doubled between 1980 and 2014, and this condition affects 600 million adults globally, which corresponds to 13% of the world’s adult population (11% of men and 15% of women) [1]. Although obesity is associated with a number of comorbidities, such as metabolic syndrome (MetS) and chronic kidney disease (CKD) [2], obese patients have historically demonstrated advantages in terms of bone density, especially in the hips and femurs [3,4].

Fifty-five patients (28 women, 27 men; 52 white) were evaluated. The causes of renal failure included hypertension (25.4%), diabetes mellitus (23.7%), glomerulonephritis (16.9%), other (10.2%) and unknown (23.7%). Because female dialysis patients often do not have regular menses, the diagnosis of menopause was based on FSH values [17,18], and menopause was present in 40% of this population. Females differed from males in many parameters, including a higher %BF (36.1 vs. 27.4, p<0.001), higher rates of turnover bone disease diagnoses (64.2% vs. 37.8%, p = 0.04), higher iPTH ([1,143 (28–3,000) vs. 358 (48–2,989) pg/mL, p = 0.02) and serum calcium levels (9.47 vs. 8.8 mg/dL, p = 0.02), higher total cholesterol (146.5 vs. 127.9 mg/dL, p = 0.03), higher OC (180.5 vs. 80 ng/mL) and lower fasting glucose levels (81 vs. 104 mg/dL, p = 0.03). Free leptin was higher in women; however, when the leptin values were normalized for age and BMI, there was no significant difference associated with gender. Phosphate binders (sevelamer in more than 80% of cases) were used by 94.5% of women and 92.6% of men, whereas calcitriol was taken by 53.5% of women and by 59.2% of men, with no significant difference between genders. In the present study, we examined the association between MetS and CKD-BMD. Patients diagnosed with MetS more frequently exhibited normal BV/TV than patients without MetS. Furthermore, several MetS components showed positive correlations with BV/TV. In contrast, high BMI without MetS diagnosis was not correlated with any of the bone histomorphometric parameters.   Source: http://doi.org/10.1371/journal.pone.0180387

 

0 0 vote
Article Rating
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments