Mineral and bone disorders in chronic kidney disease: new insights into mechanism and management

Full thermal ablation versus partial thermal ablation for secondary hyperparathyroidism: A meta-analysis

BACKGROUND

Regarding the thermal ablation treatment of refractory secondary hyperparathyroidism (SHPT), there is no consensus on the ablation range of the hyperplastic parathyroid gland. Therefore, this meta-analysis was conducted to evaluate the efficacy and complications between full and partial thermal ablation in patients with refractory SHPT.

METHODS

Databases including PubMed, EMbase, the Cochrane Library, CNKI (China National Knowledge Infrastructure), and Wanfang databases were searched from inception to July 1, 2023. Eligible studies comparing full thermal ablation and partial thermal ablation for SHPT were included. Data were analyzed using Review Manager Version 5.3.

RESULTS

Four studies were included in the meta-analysis. Three cohort studies and one randomized controlled trial involving 62 patients in the full thermal ablation group and 63 patients in the partial thermal ablation group were included. The serum parathyroid hormone (PTH), calcium, and phosphorus levels after full ablation were all lower than those after partial ablation (P < .05). There was no significant difference between the partial and full ablation groups concerning the incidence rate of severe hypocalcemia (P = .09). There was no significant difference between the partial and full ablation groups concerning symptom improvement, including bone joint pain, itching, and myasthenia (P < .05).

CONCLUSION

Full ablation was superior to partial ablation in terms of reducing PTH, calcium and phosphorus levels. Full ablation might not significantly increase the incidence of severe hypocalcemia. Larger multicentre randomized controlled trials are necessary to confirm the conclusion.

Microwave ablation versus radiofrequency ablation for patients with primary and secondary hyperparathyroidism: a meta-analysis

OBJECTIVE

Thermal ablation, including microwave ablation (MWA) and radiofrequency ablation (RFA), has been recommended for the treatment of primary hyperparathyroidism (PHPT) and refractory secondary hyperparathyroidism (SHPT). This meta-analysis was conducted to evaluate the efficacy and safety of MWA and RFA in patients with PHPT and refractory SHPT.

METHODS

Databases including PubMed, EMbase, the Cochrane Library, CNKI (China National Knowledge Infrastructure), and Wanfang were searched from inception to December 5, 2022. Eligible studies comparing MWA and RFA for PHPT and refractory SHPT were included. Data were analyzed using Review Manager software, version 5.3.

RESULTS

Five studies were included in the meta-analysis. Two were retrospective cohort studies, and three were RCTs. Overall, 294 patients were included in the MWA group, and 194 patients were included in the RFA group. Compared with RFA for refractory SHPT, MWA had a shorter operation time for a single lesion (P < 0.01) and a higher complete ablation rate for a single lesion ≥ 15 mm (P < 0.01) but did not show a difference in the complete ablation rate for a single lesion < 15 mm (P > 0.05). There were no significant differences between MWA and RFA for refractory SHPT concerning parathyroid hormone (P > 0.05), calcium (P > 0.05), and phosphorus levels (P > 0.05) within 12 months after ablation, except that calcium (P < 0.01) and phosphorus levels (P = 0.02) in the RFA group were lower than those in the MWA group at one month after ablation. There was no significant difference between MWA and RFA concerning the cure rate of PHPT (P > 0.05). There were no significant differences between MWA and RFA for PHPT and refractory SHPT concerning the complications of hoarseness (P > 0.05) and hypocalcaemia (P > 0.05).

CONCLUSION

MWA had a shorter operation time for single lesions and a higher complete ablation rate for large lesions in patients with refractory SHPT. However, there was no significant difference in efficacy and safety between MWA and RFA in cases of both PHPT and refractory SHPT. Both MWA and RFA are effective treatment methods for PHPT and refractory SHPT.

Vitamin K-Dependent Carboxylation of Osteocalcin in Bone-Ally or Adversary of Bone Mineral Status in Rats with Experimental Chronic Kidney Disease?

Chronic kidney disease (CKD) commonly occurs with vitamin K (VK) deficiency and impaired bone mineralization. However, there are no data explaining the metabolism of endogenous VK and its role in bone mineralization in CKD. In this study, we measured serum levels of phylloquinone (VK1), menaquinone 4 and 7 (MK4, MK7), and VK-dependent proteins: osteocalcin, undercarboxylated osteocalcin (Glu-OC), and undercarboxylated matrix Gla protein (ucMGP). The carboxylated osteocalcin (Gla-OC), Glu-OC, and the expression of genes involved in VK cycle were determined in bone. The obtained results were juxtaposed with the bone mineral status of rats with CKD. The obtained results suggest that the reduced VK1 level observed in CKD rats may be caused by the accelerated conversion of VK1 to the form of menaquinones. The bone tissue possesses all enzymes, enabling the conversion of VK1 to menaquinones and VK recycling. However, in the course of CKD with hyperparathyroidism, the intensified osteoblastogenesis causes the generation of immature osteoblasts with impaired mineralization. The particular clinical significance seems to have a finding that serum osteocalcin and Glu-OC, commonly used biomarkers of VK deficiency, could be inappropriate in CKD conditions, whereas Gla-OC synthesized in bone appears to have an adverse impact on bone mineral status in this model.

The Influence of Dietary Interventions on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD)

Chronic kidney disease is a health problem whose prevalence is increasing worldwide. The kidney plays an important role in the metabolism of minerals and bone health and therefore, even at the early stages of CKD, disturbances in bone metabolism are observed. In the course of CKD, various bone turnover or mineralization disturbances can develop including adynamic hyperparathyroid, mixed renal bone disease, osteomalacia. The increased risk of fragility fractures is present at any age in these patients. Nutritional treatment of patients with advanced stages of CKD is aiming at prevention or correction of signs, symptoms of renal failure, avoidance of protein-energy wasting (PEW), delaying or prevention of the occurrence of mineral/bone disturbances, and delaying the start of dialysis. The results of studies suggest that progressive protein restriction is beneficial with the progression of renal insufficiency; however, other aspects of dietary management of CKD patients, including changes in sodium, phosphorus, and energy intake, as well as the source of protein and lipids (animal or plant origin) should also be considered carefully. Energy intake must cover patients' energy requirement, in order to enable correct metabolic adaptation in the course of protein-restricted regimens and prevent negative nitrogen balance and protein-energy wasting.

Bone Disease in CKD in Children

This manuscript discusses mineral and bone disorders of chronic kidney disease (MBD-CKD) in pediatric patients with special emphasis on the underlying pathophysiology, the causes and clinical profile of growth retardation, the alterations in the growth plate, the strategies to optimize growth and the medical recommendations for prevention and treatment.

Association of Insulin Glargine Treatment with Bone Mineral Density in Patients with Type 2 Diabetes Mellitus

PURPOSE

To assess the association of type 2 diabetes mellitus (T2DM) and insulin glargine treatment with bone mineral density (BMD) in Chinese people.

METHODS

This retrospective study included 50 subjects with T2DM: 25 received oral glucose-lowering medication (ORL group), and 25 received oral glucose-lowering medication in combination with insulin glargine injection (CGI group). Thirty non-diabetic control subjects were also included. BMD was measured at lumbar vertebrae 1-4 (L1-L4), spine bone mineral density (sBMD) results summary (L2-L4), femoral neck and trochanter by dual-energy x-ray absorptiometry.

RESULTS

Compared with non-diabetic controls, people with T2DM had significantly lower mean BMD at L2 (1.073±0.120 vs 0.984±0.158), L3 (1.094±0.129 vs 0.991±0.163) and L4 (1.089±0.130 vs 0.982±0.165) (all P<0.05), significantly lower levels of serum calcium (2.02±0.22 vs 2.27±0.17 mmol/L, P<0.05), PTH (24.19±9.71 vs 31.52±8.96 pg/mL, P<0.05), and higher serum phosphate levels (1.43±0.37 vs 1.20±0.15 mmol/L, P<0.05). The CGI group had higher L2, L3 and L4 BMD and sBMD (L2-L4) (P<0.05), higher serum calcium levels (2.19±0.11 vs 1.98±0.20 mmol/L, P<0.05) and lower serum phosphate levels (1.28±0.20 vs 1.58±0.43 mmol/L, P<0.05) versus the ORL group. BMD and serum calcium levels were associated with the application of insulin glargine.

CONCLUSION

These results suggest that insulin glargine may affect bone metabolism in patients diagnosed with T2DM. The study has implications for the selection of hypoglycemic agents for diabetic patients at risk of osteoporosis.

Paricalcitol vs. cinacalcet for secondary hyperparathyroidism in chronic kidney disease: A meta-analysis

Paricalcitol and cinacalcet have been recommended to reduce parathyroid hormone (PTH) levels for patients with secondary hyperparathyroidism (SHPT) and chronic kidney disease (CKD), and they are able to reduce the risk of hypercalcemia and hyperphosphatemia. However, to date, it has remained uncertain which is the better drug. The aim of the present meta-analysis was to evaluate the effects on PTH, calcium and phosphorus metabolism between the two drugs. The PubMed, the Cochrane Library and Embase databases were searched from inception to June 1, 2019 and eligible studies comparing paricalcitol and cinacalcet for SHPT were included. Data were analysed using Review Manager version 5.3. A total of 7 trials from six articles, comprising 456 patients in the paricalcitol group and 412 patients in the cinacalcet group, were included in the meta-analysis. There were no differences in PTH levels [mean difference (MD): 71.82, 95% CI: -185.20-328.85, P=0.58] and phosphorus levels (standard MD: 0.59, 95% CI: -0.82-2.00, P=0.41). The calcium levels in the paricalcitol group were significantly higher than those in the cinacalcet group (MD: 1.10, 95% CI: 0.92-1.28, P<0.05). In conclusion, paricalcitol and cinacalcet exhibited no difference in their efficacy to control of PTH levels, as they were similarly effective in decreasing the PTH levels. They also had comparable efficacy in the management of phosphorus levels. However, cinacalcet produced a significantly greater reduction in serum calcium levels. More large multicentre randomized controlled trials are necessary to confirm the conclusions of the present analysis.

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD): Current Perspectives

Despite the availability of global and regional guidelines to curtail the adverse clinical outcomes associated with chronic kidney disease–mineral and bone disorder (CKD-MBD), most CKD patients are still affected by the consequences of abnormalities of CKD-MBD. This important clinical complication of CKD continues to be studied, in order to improve the understanding and management of CKD-MBD. Some notable discoveries include the role of fibroblast growth factor 23 (FGF23) in the pathogenesis of CKD-MBD, leading to a shift from the previous well-established classic trade-off hypothesis to the updated trade-off hypothesis. More recently, there has been a shift from the treatment of CKD-MBD based on a single level of biomarkers to serial measurements of calcium, phosphate and parathyroid hormone (PTH). Furthermore, some clinical trials have emerged after the 2009 Kidney Disease-Improving Global Outcomes (KDIGO) Guidelines, leading to the 2017 KDIGO updated recommendations. Hence, this review gives an overview of the rapidly evolving trends in CKD-MBD, linking the past and current concepts of CKD-MBD.

Characterization and assessment of potential microRNAs involved in phosphate-induced aortic calcification

Medial artery calcification, a hallmark of type 2 diabetes mellitus and chronic kidney disease (CKD), is known as an independent risk factor for cardiovascular mortality and morbidity. Hyperphosphatemia associated with CKD is a strong stimulator of vascular calcification but the molecular mechanisms regulating this process remain not fully understood. We showed that calcification was induced after exposing Sprague-Dawley rat aortic explants to high inorganic phosphate level (P_i , 6 mM) as examined by Alizarin red and Von Kossa staining. This calcification was associated with high Tissue-Nonspecific Alkaline Phosphatase (TNAP) activity, vascular smooth muscle cells de-differentiation, manifested by downregulation of smooth muscle 22 alpha (SM22α) protein expression which was assessed by immunoblot analysis, immunofluorescence, and trans-differentiation into osteo-chondrocyte-like cells revealed by upregulation of Runt related transcription factor 2 (Runx2), TNAP, osteocalcin, and osteopontin mRNA levels which were determined by quantitative real-time PCR. To unravel the possible mechanism(s) involved in this process, microRNA (miR) expression profile, which was assessed using TLDA technique and thereafter confirmed by individual qRT-PCR, revealed differential expression 10 miRs, five at day 3 and 5 at day 6 post P_i treatment versus control untreated aortas. At day 3, miR-200c, -155, 322 were upregulated and miR-708 and 331 were downregulated. After 6 days of treatment, miR-328, -546, -301a were upregulated while miR-409 and miR-542 were downregulated. Our results indicate that high P_i levels trigger aortic calcification and modulation of certain miRs. These observations suggest that mechanisms regulating aortic calcification might involve miRs, which warrant further investigations in future studies.

Extreme bony pelvic deformity in a renal transplant patient

A 35-year-old female renal transplant recipient was referred to the metabolic bone clinic because of a 15 cm loss of height. She was noted to have thoracic kyphosis and vertebral X-ray confirmed a wedge fracture of the eighth thoracic vertebra. She was managed accordingly but on subsequent follow-up mentioned in passing that her gynaecologist had been unable to obtain a cervical smear for routine screening. This led to further questioning, and the patient reported intermittent urinary stress incontinence, feelings of vaginal fullness and severe dyspareunia. It became apparent that these symptoms had been ongoing for 4 years, but the patient had not brought them to the attention of a healthcare practitioner due to feelings of embarrassment and her religious beliefs. These complaints prompted radiological investigation, which revealed extensive bony pelvic deformity, thought to be an extreme manifestation of chronic kidney disease mineral and bone disorder.

Educational intervention for metabolic bone disease in patients with chronic kidney disease: a systematic review and meta-analysis

Metabolic bone disease (MBD) is a common complication of chronic kidney disease (CKD). The currently accepted international guidelines for treatment of CKD-MBD has been published, unfortunately adequate control of serum markers of disorder, especially hyperphosphatemia, is poorly achieved. Whether educational intervention is an effective way for improving CKD-MBD remains controversial. A systematic review of educational intervention versus routine care to improve patients with CKD-MBD was conducted. All randomized controlled trials (RCTs) and quasi-RCTs examining the efficacy of educational intervention to improve patients with CKD-MBD were included. We performed a comprehensive search of several databases and sources to identify eligible trials. In addition, we searched unpublished studies by tracking the SIGLE (System for Information on Grey Literature) database. Finally, 8 RCTs and 2 quasi-RCTs containing 775 participants were included in our systematic review. The result of our study revealed that the educational intervention to patients with CKD-MBD led to an improvement of the serum phosphorus and calcium by phosphate product. Educational intervention is a beneficial supplement method in improving CKD-MBD and putting off deterioration of the disease.

Musculoskeletal manifestations of endocrine disorders

Endocrine disorders can lead to disturbances in numerous systems within the body, including the musculoskeletal system. Radiological evaluation of these conditions can demonstrate typical appearances of the bones and soft tissues. Knowledge of these patterns can allow the radiologist to suggest a diagnosis that may not be clinically apparent. This review will highlight the typical musculoskeletal findings of acromegaly, hypercortisolism, hyperthyroidism, hypothyroidism, hyperparathyroidism, pseudo- and pseudopseudohypoparathyroidism, and diabetes mellitus. The radiological manifestations of each of these endocrine disorders, along with a brief discussion of the pathophysiology and clinical implications, will be discussed.

Association of serum alkaline phosphatase with mortality in non-selected European patients with CKD5D: an observational, three-centre survival analysis

OBJECTIVES

For characterisation of mineral bone disease in chronic kidney disease (CKD), laboratory surrogates have been suggested. This observational should investigate the association of total and skeletal alkaline phosphatase (AP) with mortality of patients undergoing maintenance renal replacement therapy.

SETTING

Three renal outpatient centers in eastern-central Germany (secondary and tertiary care).

PARTICIPANTS

Complete survival and laboratory datasets were available in 407 of 493 patients. Age and gender distribution was equivalent to a general population with end-stage CKD (CKD5D). Patients were included between 2008 and 2010 if at least 2 weeks of maintenance treatment were documented.

PRIMARY OUTCOME MEASURES

Mortality was estimated by setting the end of dialysis date as event date. Events other than death (change to another centre, life-sustaining renal function or transplantation) were censored.

RESULTS

The OR to die within follow-up for patients in the higher of two total AP strata was 2.70 (95% CI 1.76 to 4.15). In univariate Kaplan-Meier analysis, total AP had a strong association with all-cause mortality (LogRank=24.1, p<0.001). Mean total AP and individual lowest skeletal AP, but not mean skeletal AP entered step-wise Cox models for survival from dialysis start (χ(2)=22.4; p<0.001) after adjusting for age, Kt/V, diabetes and vintage. Mean values of skeletal, total AP and parathyroid hormone were 14.8±8.9 µg/L, 91.9±55.3 U/L and 188±164 ng/L, respectively. Skeletal and total AP were highly correlated (R=0.86; p<0.001).

CONCLUSIONS

This unselected CKD5D population exhibited a clinical significant association of total AP with crude mortality and a stronger death risk association of total AP and individual lowest skeletal AP with crude mortality.

Paricalcitol- or cinacalcet-centred therapy affects markers of bone mineral disease in patients with secondary hyperparathyroidism receiving haemodialysis: results of the IMPACT-SHPT study

BACKGROUND

In this Phase 4 international study, efficacy and safety of paricalcitol-centred therapy were compared with that of cinacalcet-centred therapy for the treatment of chronic kidney disease (CKD)-associated secondary hyperparathyroidism (SHPT) in patients undergoing haemodialysis (ClinicalTrials.gov identifier NCT00977080).

METHODS

Patients ≥ 18 years of age with Stage 5 CKD and SHPT [intact parathyroid hormone (iPTH) level of 300-800 pg/mL, calcium level of 8.4-10.0 mg/dL and phosphate concentration of ≤ 6.5 mg/dL] who were undergoing haemodialysis were included. Patients were randomized by mode of paricalcitol administration [i.e. intravenous (IV) or oral strata] to receive paricalcitol- or cinacalcet-centred therapy for ≤ 28 weeks. Changes in metabolic markers [total alkaline phosphatase (AP), bone-specific AP and fibroblast growth factor-23 (FGF-23)] and the proportion of patients in each treatment group who achieved an iPTH level of 150-300 pg/mL during Weeks 8, 16 and 21-28 as a composite value were evaluated.

RESULTS

Compared with cinacalcet-centred therapy, levels of both bone turnover markers were significantly reduced from baseline with IV and oral paricalcitol-centred treatment (P < 0.05 for both dosing strata) at Weeks 8, 16 and 28. Levels of FGF-23 were increased with paricalcitol versus cinacalcet-centred treatment. A greater proportion of patients receiving paricalcitol-centred therapy achieved target iPTH levels (i.e. 150-300 pg/mL) throughout the study in the IV and oral dosing strata compared with patients receiving cinacalcet-centred treatment.

CONCLUSIONS

In patients with CKD and SHPT undergoing haemodialysis, paricalcitol-centred therapy reduced circulating bone turnover markers and iPTH levels and increased FGF-23 levels compared with cinacalcet-centred treatment.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT00977080.