Longitudinal Measurements of FGF23, Sarcopenia, Frailty and Fracture in Older Community Dwelling Women.

BACKGROUND: FGF23 has been associated with frailty and functional performance in older individuals, but the association to sarcopenia is unknown. OBJECTIVES: To investigate the association between FGF23, frailty, sarcopenia and fractures in older community dwelling women. DESIGN: Prospective longitudinal cohort study. SETTING: Malmö, Sweden. PARTICIPANTS: 995 75-year-old women, followed prospectively for ten years, with re-investigations after five (n=667) and ten (n=324) years. MEASUREMENTS: C-terminal levels of FGF23 were measured and a frailty index of 'deficits in health' created. Sarcopenia was defined by low muscle mass and strength and "probable sarcopenia" by low muscle mass only. Incident fractures were continuously registered for 10-years. Based on tertiles of FGF23, odds ratio for frailty, sarcopenia and probable sarcopenia was investigated using logistic regression models adjusted for: eGFR, PTH, calcium, vitamin D and phosphate. Fracture-free survival during 10-year follow-up was depicted using Kaplan Meier curves. RESULTS: While fracture-free survival did not differ between tertiles, women in the highest tertile of FGF23 had lower muscle strength and gait speed, and higher proportion with impaired mobility at baseline. At age 75, these women had higher odds of also being frail (ORadj 1.6 (95% CI 1.1-2.4)) and suffering from probable sarcopenia (ORadj 1.8 (95% CI 1.1-3.1)), but not sarcopenia. At follow-up the association between FGF23 and probable sarcopenia was not evident. While the association with frailty was attenuated at age 80 after adjustment (ORadj 1.6 (95% CI 1.0-2.5)), women in the highest tertile had higher odds of being frail at age 85 (ORadj 3.4 (95% CI 1.7-6.6)). CONCLUSIONS: FGF23 may be a promising clinical marker for muscle strength, functional performance, and frailty in older women, but not for future fragility fractures. Whether FGF23 is also associated with sarcopenia requires further investigation.

Low bone mineral density is associated with hypogonadism and cranial irradiation in male childhood cancer survivors.

We investigated if bone mineral density was related to testosterone deficiency and/or previous cancer treatment in men who were childhood cancer survivors. Men with untreated testosterone deficiency or previous treatment with cranial irradiation were at increased risk of impaired bone health. Prevention of osteoporosis should be considered in their follow-up. INTRODUCTION: Childhood cancer survivors (CCS) are at increased risk of hypogonadism. Reduced bone mineral density (BMD) has been reported in CCS but it is unclear whether this is due to hypogonadism or a direct effect of cancer therapy. This study investigated BMD in CCS, and association with hypogonadism, previous treatment and cancer type. METHODS: Investigation of 125 CCS (median age 33.7 at inclusion; 9.6 at diagnosis) and 125 age-matched population controls. Serum testosterone and luteinizing hormone were assayed and BMD at total hip and lumbar spine L1-L4 measured. The mean difference in BMD (g/cm2; 95% CI) between CCS and controls was analysed. Odds ratios (OR; 95% CI) for low BMD were also calculated. RESULTS: Overall, BMD in the CCS cohort did not significantly differ from controls. However, compared with eugonadal CCS, the CCS with untreated hypogonadism had lower BMD at the hip (mean difference - 0.139 (- 0.210; - 0.067); p < 0.001) and spine (- 0.102 (- 0.174; - 0.030); p = 0.006). They also had a higher risk of low hip BMD (OR 4.1 (1.3; 14); p = 0.018). CCS treated with cranial irradiation also had lower BMD (hip - 0.076 (- 0.133; - 0.019); p = 0.009; spine - 0.071 (- 0.124; - 0.018); p = 0.009) compared with controls. The latter associations remained statistically significant after adjustment for hypogonadism. CONCLUSIONS: CCS with hypogonadism or previously treated with cranial irradiation are at increased risk of impaired bone health. Prevention of osteoporosis should be considered as an important part in future follow-up of these men.

Risk of low bone mineral density in testicular germ cell cancer survivors: association with hypogonadism and treatment modality.

The cure rate of testicular cancer exceeds 95%, but testicular cancer survivors (TCS) are at increased risk of hypogonadism (HG). It has been suggested that TCS have reduced bone mineral density (BMD), but it is unclear whether this is related to HG or a direct effect of cancer therapy. The aim of this study was to evaluate whether TCS have decreased BMD, and if BMD is related to HG and/or the cancer treatment given. We investigated 91 TCS (mean age at diagnosis: 31 years; mean 9.3 years follow-up) and equal number of age matched controls (mean age at inclusion 40.3 years and 41.2 years, respectively). Total testosterone and LH were measured. BMD was determined using dual-energy X-ray absorptiometry (DXA). Low BMD (LBD) was defined as Z-score <-1. Compared to eugonadal TCS, both TCS with untreated HG (mean difference: -0.063 g/cm2 ; 95% CI: -0.122; -0.004 p = 0.037) and TCS receiving androgen replacement (mean difference -0.085 g/cm2 ; 95% CI: -0.168; -0.003; p = 0.043) presented with statistically significantly 6-8% lower hip BMD. At the spine, L1-L4, an 8% difference reached the level of statistical significance only for those with untreated HG (mean difference: -0.097 g/cm2 ; 95% CI: -0.179; -0.014; p = 0.022). TCS with untreated HG had significantly increased OR for spine L1-L4 LBD (OR = 4.1; 95% CI: 1.3; 13; p = 0.020). The associations between the treatment given and BMD were statistically non-significant, both with and without adjustment for HG. In conclusion, TCS with HG are at increased risk of impaired bone health. Prevention of osteoporosis should be considered as an important part in future follow up of these men.