Serum phosphate levels modify the impact of parathyroid hormone levels on renal outcomes in kidney transplant recipients

New triple therapy for the diagnosis of CKD-MBD: a cross-sectional study in Shanxi province

OBJECTIVES

To seek a triple combination of biomarkers for early diagnosis of chronic kidney disease-mineral and bone metabolic disorder and to explore the diagnostic efficacy of β2-microglobulin, parathyroid hormone and blood urea nitrogen in chronic kidney disease-mineral and bone metabolic disorder.

PARTICIPANTS

We collected medical records of 864 patients with chronic kidney disease (without direct contact with patients) and divided them into two groups based on the renal bone disease manifestations of all patients.

PRIMARY AND SECONDARY OUTCOME MEASURES

There were 148 and 716 subjects in the Chronic kidney disease-mineral and bone metabolic disorder and the control groups, respectively. The aggregated data included basic information and various clinical laboratory indicators, such as blood lipid profile, antibody and electrolyte levels, along with renal function-related indicators.

RESULTS

It was observed that most renal osteopathy occurs in the later stages of chronic kidney disease. In the comparison of two clinical laboratory indicators, 16 factors were selected for curve analysis and compared. We discovered that factors with high diagnostic values were β2-microglobulin, parathyroid hormone and blood urea nitrogen.

CONCLUSIONS

The triple combination of β2-microglobulin+parathyroid hormone+blood urea nitrogen indicators can play the crucial role of a sensitive indicator for the early diagnosis of chronic kidney disease-mineral and bone metabolic disorder and in preventing or delaying the progress of chronic kidney disease-mineral and bone metabolic disorder.

Bone and Mineral Disorder in Renal Transplant Patients: Overview of Pathology, Clinical, and Therapeutic Aspects

Renal transplantation (RTx) allows us to obtain the resolution of the uremic status but is not frequently able to solve all the metabolic complications present during end-stage renal disease. Mineral and bone disorders (MBDs) are frequent since the early stages of chronic kidney disease (CKD) and strongly influence the morbidity and mortality of patients with CKD. Some mineral metabolism (MM) alterations can persist in patients with RTx (RTx-p), as well as in the presence of complete renal function recovery. In those patients, anomalies of calcium, phosphorus, parathormone, fibroblast growth factor 23, and vitamin D such as bone and vessels are frequent and related to both pre-RTx and post-RTx specific factors. Many treatments are present for the management of post-RTx MBD. Despite that, the guidelines that can give clear directives in MBD treatment of RTx-p are still missed. For the future, to obtain an ever-greater individualisation of therapy, an increase of the evidence, the specificity of international guidelines, and more uniform management of these anomalies worldwide should be expected. In this review, the major factors related to post-renal transplant MBD (post-RTx-MBD), the main mineral metabolism biochemical anomalies, and the principal treatment for post-RTx MBD will be reported.

Cholecalciferol Supplementation Attenuates Bone Loss in Incident Kidney Transplant Recipients: A Prespecified Secondary Endpoint Analysis of a Randomized Controlled Trial

Vitamin D deficiency, persistent hyperparathyroidism, and bone loss are common after kidney transplantation (KTx). However, limited evidence exists regarding the effects of cholecalciferol supplementation on parathyroid hormone (PTH) and bone loss after KTx. In this prespecified secondary endpoint analysis of a randomized controlled trial, we evaluated changes in PTH, bone metabolic markers, and bone mineral density (BMD). At 1 month post-transplant, we randomized 193 patients to an 11-month intervention with cholecalciferol (4000 IU/d) or placebo. The median baseline 25-hydroxyvitamin D (25[OH]D) level was 10 ng/mL and 44% of participants had osteopenia or osteoporosis. At the end of the study, the median 25(OH)D level was increased to 40 ng/mL in the cholecalciferol group and substantially unchanged in the placebo group. Compared with placebo, cholecalciferol significantly reduced whole PTH concentrations (between-group difference of -15%; 95% confidence interval [CI] -25 to -3), with greater treatment effects in subgroups with lower 25(OH)D, lower serum calcium, or higher estimated glomerular filtration rate (p_int  < 0.05). The percent change in lumbar spine (LS) BMD from before KTx to 12 months post-transplant was -0.2% (95% CI -1.4 to 0.9) in the cholecalciferol group and -1.9% (95% CI -3.0 to -0.8) in the placebo group, with a significant between-group difference (1.7%; 95% CI 0.1 to 3.3). The beneficial effect of cholecalciferol on LS BMD was prominent in patients with low bone mass p_int  < 0.05). Changes in serum calcium, phosphate, bone metabolic markers, and BMD at the distal radius were not different between groups. In mediation analyses, change in whole PTH levels explained 39% of treatment effects on BMD change. In conclusion, 4000 IU/d cholecalciferol significantly reduced PTH levels and attenuated LS BMD loss after KTx. This regimen has the potential to eliminate vitamin D deficiency and provides beneficial effects on bone health even under glucocorticoid treatment. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Association between serum uric acid and depressive symptoms stratified by low-grade inflammation status

Despite increasing evidence for an association between circulating uric acid (UA) and depression, the directionality of this association remains unclear and is potentially moderated by low-grade inflammation. Thus, the present study aimed to investigate the cross-sectional association between serum UA concentration and depressive symptoms in Korean individuals with and without low-grade inflammation, as measured using serum high-specific C-reactive protein (hs-CRP) levels. The final study sample comprised 4188 participants, aged 19–79 years, from the Korea National Health and Nutrition Examination Study 2016. Data on serum uric acid (UA) concentrations, serum hs-CRP levels, Patient Health Questionnaire-9 (PHQ-9) scores, and relative covariates were retrieved. Negative binomial regression with adjustment for the complex sample design was used to analyze the associations. After adjusting for covariates, log-transformed serum UA concentrations and total PHQ-9 scores were positively associated (incidence rate ratio [IRR] = 1.34 [95% confidence interval [CI] = 1.09–1.66]) for participants without low-grade inflammation and inversely associated (IRR = 0.64 [95% CI = 0.45–0.92]) for participants with low-grade inflammation. In conclusion, the direction of the association between serum UA and depressive symptoms was the opposite in participants with and without low-grade inflammation. The study has the limitation of potential uncontrolled confounders.

C-terminal and intact FGF23 in kidney transplant recipients and their associations with overall graft survival

Background

Increased fibroblast growth factor 23 (FGF23) is a risk factor for mortality, cardiovascular disease, and progression of chronic kidney disease. Limited data exist comparing the association of either c-terminal FGF23 (cFGF23) or intact FGF23 (iFGF23) in kidney transplant recipients (KTRs) with overall (all-cause) graft loss.

Methods

We conducted a prospective observational cohort study in 562 stable kidney transplant recipients. Patients were followed for graft loss and all-cause mortality for a median follow-up of 48 months.

Results

During a median follow-up of 48 months, 94 patients had overall graft loss (primary graft loss or death with functioning graft). Both cFGF23 and iFGF23 concentrations were significantly higher in patients with overall graft loss than those without (24.59 [11.43–87.82] versus 10.67 [5.99–22.73] pg/ml; p < 0.0001 and 45.24 [18.63–159.00] versus 29.04 [15.23–60.65] pg/ml; p = 0.002 for cFGF23 and iFGF23, respectively). Time-dependent ROC analysis showed that cFGF23 concentrations had a better discriminatory ability than iFGF23 concentrations in predicting overall (all-cause) graft loss. Cox regression analyses adjusted for risk factors showed that cFGF23 (HR for one unit increase of log transformed cFGF23: 1.35; 95% CI, 1.01–1.79; p = 0.043) but not iFGF23 (HR for one unit increase of log transformed iFGF23: 0.97; 95% CI, 0.75–1.25; p = 0.794) was associated with the overall graft loss.

Conclusion

Elevated cFGF23 concentrations at baseline are independently associated with an increased risk of overall graft loss. iFGF23 measurements were not independently associated with overall graft loss. The cFGF23 ELISA might detect bioactive FGF23 fragments that are not detected by the iFGF23 ELISA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02329-7.