Denosumab Improves Glomerular Filtration Rate in Osteoporotic Patients With Normal Kidney Function by Lowering Serum Phosphorus

Novel genetic mutation associated with hyperphosphatemic familial tumoral calcinosis/hyperostosis-hyperphosphatemia syndrome treated with denosumab: a case report

In this case report, a novel N-acetylgalactosaminyltransferase 3 homozygous mutation (c.782 G>A; p.R261Q) associated with hyperphosphatemic familial tumoral calcinosis/hyperostosis-hyperphosphatemia syndrome is described. The patient had elbow, pelvis, and lower limb pain and a hard mass in the hip and olecranon regions. Increased levels of inorganic phosphorus (Pi) and C-reactive protein were observed. After treating the patient with conventional drugs, we tested denosumab, which reduced but did not normalize the Pi.

Height loss is associated with decreased kidney function: The Japan Specific Health Checkups (J-SHC) Study

AIM

Height loss that occurs with aging is a common phenomenon associated with musculoskeletal abnormalities, such as osteoporosis and sarcopenia. Notably, such height loss is also associated with poor outcomes, including cardiovascular disease and mortality. In this study, we investigated the relationship between height loss and kidney outcome.

METHODS

This longitudinal study includes data from the Japan Specific Health Checkups Study from 2008 to 2014. Height loss was estimated using the first three visits (visits 1-3), and kidney outcomes were evaluated using data from the following visits (visit 3 to the last visit). The annual height change for each participant was estimated using mixed-effects model, and participants were divided into five groups according to the quintile of the rate. The association between height change and the incidence of 1.5-fold increase in serum creatinine level from baseline was analyzed using Cox regression analysis. The decline rates of estimated glomerular filtration rate among the groups were compared using a mixed-effects model.

RESULTS

In total, 187 682 participants were included in the analyses. The median rate of height change was -0.11 cm/year. The adjusted hazard ratio (95% confidence interval) for 1.5-fold increase in serum creatinine level in participants with the steepest category of height decline (Q1; Quintile 1) was 1.45 (1.26-1.67) compared with the reference (Q4; Quintile 4). The decline of the estimated glomerular filtration rate in Q1 (-1.25 mL/min/1.73 m² /year) was significantly higher than that of the reference: Q4 (-0.92 mL/min/1.73 m² /year) (P for interaction <0.001).

CONCLUSION

Height loss is associated with a rapid decline in kidney function. Geriatr Gerontol Int 2023; ••: ••-••.

Focusing on Phosphorus Loads: From Healthy People to Chronic Kidney Disease

Phosphorus is an essential micromineral with a key role in cellular metabolism and tissue structure. Serum phosphorus is maintained in a homeostatic range by the intestines, bones, and kidneys. This process is coordinated by the endocrine system through the highly integrated actions of several hormones, including FGF23, PTH, Klotho, and 1,25D. The excretion kinetics of the kidney after diet phosphorus load or the serum phosphorus kinetics during hemodialysis support that there is a "pool" for temporary phosphorus storage, leading to the maintenance of stable serum phosphorus levels. Phosphorus overload refers to a state where the phosphorus load is higher than is physiologically necessary. It can be caused by a persistently high-phosphorus diet, renal function decline, bone disease, insufficient dialysis, and inappropriate medications, and includes but is not limited to hyperphosphatemia. Serum phosphorus is still the most commonly used indicator of phosphorus overload. Trending phosphorus levels to see if they are chronically elevated is recommended instead of a single test when judging phosphorus overload. Future studies are needed to validate the prognostic role of a new marker or markers of phosphorus overload.

Effect of denosumab on renal function in women with osteoporosis evaluated using cystatin C

Objectives

To investigate renal function during denosumab therapy using the estimated glomerular filtration rate based on cystatin C (eGFRcys) which is more accurate than creatinine (eGFRcr) for renal function.

Methods

Bone mineral densities (BMDs) of lumbar spine and hip regions, eGFRcys, eGFRcr, creatinine clearance (Ccr), and serum total homocysteine (S-Hcy) were measured during 2-year denosumab therapy in 53 women with osteoporosis naïve to anti-osteoporosis drugs (new group) and 64 women who were switched from long-term bisphosphonate treatment to denosumab therapy (switch group).

Results

There were no significant differences in age, eGFRcr, Ccr, eGFRcys, and S-Hcy levels at baseline between the groups. BMDs in the lumbar spine, femoral neck, and total hip increased significantly after 2-year denosumab therapy in both groups. eGFRcr decreased in the switch group, and Ccr decreased in both groups; however, eGFRcys and S-Hcy levels did not change significantly in either group. To investigate the causal factors associated with the decrease in eGFRcr and Ccr, multiple regression analysis was performed in all patients. Denosumab initiation within 3 months after fracture and eGFRcr or Ccr at baseline were independent factors for the decrease in eGFRcr or Ccr during the 2-year denosumab therapy. Decline in creatinine-based renal function could be reflected by increased muscle mass during the ongoing recovery from fracture.

Conclusions

Renal function was preserved in all patients, including those in the switch group during denosumab therapy. Creatinine-based renal function should be cautiously interpreted during denosumab therapy in patients with recent fractures.

Efficacy of romosozumab in patients with osteoporosis on maintenance hemodialysis in Japan; an observational study

INTRODUCTION

Romosozumab reportedly increases bone mineral density (BMD) potently but might adversely affect cardiovascular disease (CVD). We evaluated the efficacy of romosozumab in osteoporotic HD patients with a high risk of fracture.

MATERIALS AND METHODS

This was a single-center 1-year study in Japanese HD patients. Among 96 HD romosozumab-treated HD patients with high risk of fracture, 76 HD patients completed 1 year of subcutaneous administration of romosozumab (210 mg/4 weeks) for 1 year. Romosozumab-untreated HD patients (n = 55) were also included. Changes in BMD and serum markers, together with fracture occurrence, and CVD events, were monitored.

RESULTS

During romosozumab treatment of 76 HD patients, BMD time-dependently increased significantly by 15.3% ± 12.9% at the lumbar spine (L1-4), and 7.2% ± 8.3% at the femoral neck at 1 year. Serum BAP and total P1NP increased significantly and serum TRACP-5b decreased at 4 weeks. Fragility fractures occurred in three (3.8%) patients. Hypocalcemia occurred at 4-48 weeks despite the increased dosing of active vitamin-D derivatives, but without any symptom. New CVD events occurred in 5.2% of romosozumab-treated HD patients and10.9% in romosozumab-untreated HD patients.

CONCLUSIONS

BMD was increased significantly during romosozumab treatment at the lumbar spine, and the femoral neck, respectively, at 1 year in HD patients. Hypocalcemia occurred but without any intolerable event. There was no apparent increase in CVD events during 1 year of study, suggesting romosozumab as a promising agent for HD patients with severe osteoporosis.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

Importance of Considering Malnutrition and Sarcopenia in Order to Improve the QOL of Elderly Hemodialysis Patients in Japan in the Era of 100-Year Life

In the current aging society of Japan, malnutrition and resultant sarcopenia have been widely identified as important symptomatic indicators of ill health and can cause impairments of longevity and quality of life in older individuals. Elderly individuals are recommended to have sufficient calorie and protein intake so as to enjoy a satisfactory quality of life, including maintaining activities of daily living in order to avoid emaciation and sarcopenia. The prevalence of emaciation and sarcopenia in elderly hemodialysis (HD) patients in Japan is higher than in non-HD elderly subjects due to the presence of malnutrition and sarcopenia associated with chronic kidney disease (CKD). Furthermore, comorbidities, such as diabetes and osteoporosis, induce malnutrition and sarcopenia in HD patients. This review presents findings regarding the mechanisms of the development of these early symptomatic conditions and their significance for impaired QOL and increased mortality in elderly HD patients.

Effects of denosumab as compared with parathyroidectomy regarding calcium, renal, and bone involvement in osteoporotic patients with primary hyperparathyroidism

PURPOSE

To evaluate the effects of denosumab (Dmb) on calcium, renal, and bone involvement in osteoporotic patients with primary hyperparathyroidism (PHPT) and compare with those who underwent a parathyroidectomy (PTX) procedure.

METHODS

This retrospective, longitudinal study included patients treated with Dmb (60 mg) once every 6 months (n = 19) and those who successfully underwent a PTX procedure (n = 19) corrected calcium (cCa), eGFR, bone mineral density (BMD) in the lumbar spine (LS), total hip (TH), and femoral neck (FN) and LS-trabecular bone score (TBS) changes at 1 year after beginning Dmb or undergoing PTX were measured.

RESULTS

Dmb group had older age, and showed milder disease activity and lower eGFR as compared with PTX group. In PTX group, cCa and eGFR were significantly decreased following surgery, while those were stable in Dmb group. There were significant increases in LS, TH, and FN-BMD in both Dmb (LS: 6.0 ± 0.8%, TH: 3.7 ± 1.0%, FN: 4.3 ± 1.5%) and PTX (LS: 11.2 ± 1.5%, TH: 7.5 ± 1.5%, FN: 7.9 ± 2.1%) groups. In Dmb group, LS-TBS was significantly improved by 3.0 ± 1.0%, while TBS change in PTX group approached significance (2.8 ± 1.5%). Percent change in TH-BMD was significantly correlated with baseline tartrate-resistant acid phosphatase-5b (TRACP-5b) in both groups.

CONCLUSIONS

Dmb treatment not only increased BMD, dependent on bone turnover status, the same as PTX, but also improved LS-TBS. In addition, it did not decrease the level of eGFR, whereas PTX did. These results suggest that Dmb treatment help in the clinical management of osteoporotic patients with PHPT who do not undergo surgery as alternative to PTX.

Serum Sclerostin But Not DKK-1 Correlated with Central Arterial Stiffness in End Stage Renal Disease Patients

Sclerostin and dickkopf-1 (DKK1) played a role in the development of cardiovascular diseases and arterial stiffness in chronic kidney disease (CKD) patients but with controversial results of patients in end-stage renal disease (ESRD) including hemodialysis (HD) and peritoneal dialysis (PD). This study aimed to examine the association between the mode of dialysis or the values of sclerostin or DKK1 and carotid-femoral pulse wave velocity (cfPWV) in ESRD patients. There were 122 HD and 72 PD patients enrolled in this study. By a validated tonometry system, cfPWV was measured and then segregated patients into values of >10 m/s as the high central arterial stiffness (AS) group and values ≤ 10 m/s as the control group. Serum levels of sclerostin and DKK1 were measured using a commercial enzyme-linked immunosorbent assay kit. Possible risk factors for the development of AS were analyzed by logistic regression analysis. There were 21 (29.2%) of PD and 53 (43.4%) of HD in the high AS group. Compared to patients in the control group, those in the high AS group were older, had more comorbidities, had higher systolic blood pressure, and had higher serum levels of fasting glucose, C-reactive protein, and sclerostin. Levels of sclerostin (adjusted OR 1.012, 95% CI. 1.006–1.017, p = 0.0001) was found to be an independent predictor of high AS in ESRD patients by multivariate logistic regression analysis. Furthermore, receiver operating characteristic curve analysis showed the optimal cut-off values of sclerostin for predicting AS was 208.64 pmol/L (Area under the curve 0.673, 95% CI: 0.603–0.739, p < 0.001). This study showed that serum levels of sclerostin, but not DKK1 or mode of dialysis, to be a predictor for high central AS in ESRD patients.