Impact of urinary calcium excretion on kidney, bone, and cardiovascular systems in patients with bone biopsy proven osteoporosis: a longitudinal long-term follow-up study

The impact of urine calcium on kidney, bone, and cardiovascular systems in osteoporosis is not well-known. In this 7-year-follow-up study, high urine calcium did not affect kidney function but increased risk of kidney stones, while low urine calcium increased cardiovascular diseases. Maintaining normal urine calcium is beneficial for bone health.

PURPOSE

Hypercalciuria is common in patients with osteoporosis. However, the long-term effect of urinary calcium excretion (UCaE) on patients' health is not well-examined. The current study aims to assess the impact of UCaE on kidney, bone, and cardiovascular outcomes in patients with bone biopsy proven osteoporosis.

METHODS

Longitudinal study of all patients with osteoporosis who underwent bone biopsy and 24-h urine collection between 2008 and 2015 in the University of Kentucky. DXA scans, serum markers, kidney function, and cardiovascular events were recorded until last clinic visit in 2021. Exclusion criteria were secondary osteoporosis or conditions that might substantially impact UCaE. The significant results in univariate analysis were confirmed in multi-variable regression models involving clinically important covariates that might impact patients' outcomes.

RESULTS

Study included 230 patients with mean follow-up of 7.2 ± 2.9 years. The mean age was 61 years, and the mean eGFR at baseline was 85 ± 19 ml/min/1.73 m². Low bone turnover (LBT) was present in 57% and high bone turnover (HBT) in 43% of patients. Hypercalciuria was found in one-third of patients with no difference between LTB and HTB. UCaE correlated positively with eGFR but did not affect the rate of eGFR decline over time. Higher UCaE predicted kidney stones development. We observed U-shaped effect of UCaE on bone health. Hypercalciuria predicted loss of BMD at all sites, but also hypocalciuria was associated with higher loss in total hip BMD. Upper limb fractures were the most observed fractures, and their incidence was higher in patients with hyper- or hypo-calciuria. Lower UCaE independently predicted development of major adverse cardiac events (MACE) and cardiovascular disease (CVD).

CONCLUSION

UCaE correlated with eGFR but it did not affect the change of eGFR over time. Patients with normal UCaE had lower incidence of upper limb fractures and less reduction in BMD. Low UCaE predicted MACE and CVD.

Management of osteoporosis in patients with chronic kidney disease

Patients with CKD have a 4-fivefold higher rate of fractures. The incidence of fractures increases with deterioration of kidney function. The process of skeletal changes in CKD patients is characterized by compromised bone strength because of deterioration of bone quantity and/or quality. The fractures lead to a deleterious effect on the quality of life and higher mortality in patients with CKD. The pathogenesis of bone loss and fracture is complex and multi-factorial. Renal osteodystrophy, uremic milieu, drugs, and systemic diseases that lead to renal failure all contribute to bone damage in CKD patients. There is no consensus on the optimal diagnostic method of compromised bone assessment in patients with CKD. Bone quantity and mass can be assessed by dual-energy x-ray absorptiometry (DXA) or quantitative computed tomography (QCT). Bone quality on the other side can be assessed by non-invasive methods such as trabecular bone score (TBS), high-resolution bone imaging methods, and invasive bone biopsy. Bone turnover markers can reflect bone remodeling, but some of them are retained by kidneys. Understanding the mechanism of bone loss is pivotal in preventing fracture in patients with CKD. Several non-pharmacological and therapeutic interventions have been reported to improve bone health. Controlling laboratory abnormalities of CKD-MBD is crucial. Anti-resorptive therapies are effective in improving BMD and reducing fracture risk, but there are uncertainties about safety and efficacy especially in advanced CKD patients. Accepting the prevalent of low bone turnover in patients with advanced CKD, the osteo-anabolics are possibly promising. Parathyroidectomy should be considered a last resort for intractable cases of renal hyperparathyroidism. There is a wide unacceptable gap in osteoporosis management in patients with CKD. This article is focusing on the updated management of CKD-MBD and osteoporosis in CKD patients. Chronic kidney disease deteriorates bone quality and quantity. The mechanism of bone loss mainly determines pharmacological treatment. DXA and QCT provide information about bone quantity, but assessing bone quality, by TBS, high-resolution bone imaging, invasive bone biopsy, and bone turnover markers, can guide us about the mechanism of bone loss.

A cross-sectional study to evaluate the validity of a novel patient-reported outcome measure of medication adherence in Type 2 Diabetes

Introduction

The average medication adherence (MA) among patients in developed countries living with a chronic disease is estimated to be roughly 50%.(1) Non-adherence is multi-factorial, owing to socio-economic and clinical factors, as well as arguably the most important factor, patients’ health beliefs and experiences. Patient Reported Outcome Measures (PROMs) are often uni-dimensional in their assessment of drivers of MA. This study has evaluated a novel PROM as part of a wider international research initiative focused on Type 2 Diabetes (T2D) which assesses four key factors of MA referred to as Social (S), Psychological (P), Usage (U) and Rationale (R), in short SPUR®.

Aim

To compare the validity of SPUR® against previously validated PROMs in patients with T2D.

Methods

This South London cross-sectional study surveyed adult participants with a confirmed diagnosis of T2D prescribed a minimum of one anti-hyperglycaemic medicine. Surveys were administered face-to-face by community pharmacists using a convenience sampling method based on interactions with pharmacy patients. The survey consisted of questions relating to socio-demographic and clinical data, the SPUR® tool and three previously validated PROMs (BeMQ-General®, MARS-10® and BeMQ-Specific®) as comparators to evaluate factors P, U and R respectively. The Medication Possession Ratio (MPR), a measure of a patient’s pill count in a given time period, was used as an objective comparator of adherence. Pearson’s correlation coefficients (r) were calculated to determine the strength of association between the validated PROMs and SPUR®, with T tests used as a measure of significance (p=<0.05) as an evaluation of validity for SPUR®.

Results

The survey response rate was 21.6% (n=149/690). The modal age range for participants was 60–69 years of age (40.1%, n=60). Participants were predominantly educated to degree level (29.5%, n=44), White (48.3%, n=72) and retired (28.9%, n=43). Overall, 47.6% (n=71) of participants identified as female. Body Mass Index (BMI) data were available for 88.6% (n=132) of the sample with 42.4% (n=56/132) reporting a BMI >30. In ascending order, moderate to strong positive correlations were observed between SPUR® and the comparative PROMs for factors P (r=0.464, p=<0.0001), U (r=0.595, p=<0.0001) and R (r=0.719, p=<0.0001), indicating SPUR® to be a reliable measure of those MA factors. When assessing MA objectively, SPUR® demonstrated the strongest correlation (r=0.281, p=<0.0001) to MPR compared with the validated tools, with MARS-10® as the closest comparator (r=0.266, p=0.001). Despite this, SPUR® did not overestimate MA, 83.8% (n=125) of the sample was identified as adherent based on MPR compared to 53% (n=79) with SPUR®. The latter more closely reflecting HbA1c data which identified 55.4% (n=31/56) as adherent.

Conclusion

Study strengths include the implementation of validated PROMs and two objective MA measures; however, the study sample size was limited. SPUR® has demonstrated its validity against validated PROMs whilst predicting adherence levels without exaggeration, which is often attributed to crude objective measures such as MPR.(2) SPUR® may therefore holistically identify the multiple factors linked to non-adherence, thus supporting the design of individualised interventions.. Such interventions are deemed by the World Health Organisation as potentially more impactful than developing new treatments.(1)

References

1. Eduardo Sabaté (WHO/NMH/CCH). Adherence to long-term therapies: policy for action. World Heal Organ. Published online 2001.

2. Long JA, Wang A, Medvedeva EL, et al. Glucose control and medication adherence among veterans with diabetes and serious mental illness: Does collocation of primary care and mental health care matter? Diabetes Care. Published online 2014. doi:10.2337/dc13-0051

Posterior urethral valves: Metabolic consequences in a cohort of patients

BACKGROUND

Despite the improvements in diagnosis and management of posterior urethral valves (PUVs), about one third of patients develop chronic kidney disease (CKD). Children with PUVs might have abnormal calcium, phosphorus, vitamin D and parathyroid hormone levels, which could affect their bone growth and overall health.

OBJECTIVE

The aim was to determine the relationship between kidney function, vitamin D deficiency and secondary hyperparathyroidism in children with PUVs.

PATIENTS AND METHODS

Sixty-four children with PUVs were followed for a period of 3.64 ± 2.50 years after their initial presentation and management. Their laboratory parameters were compared with 20 age-, gender- and race-matched children in a control group, including: serum calcium, phosphorus, intact parathyroid hormone (iPTH), 25-hydroxyvitamin D levels, and kidney function.

RESULTS

Children with PUVs had significantly lower estimated kidney function (P = 0.006) and vitamin D levels (P < 0.001) and higher iPTH levels (P = 0.042). There were no significant between-group differences in serum calcium, phosphorus, alkaline phosphatase, sodium, potassium, and bicarbonate levels. There was a strong correlation between the degree of vitamin D deficiency and hyperparathyroidism and the degree of kidney dysfunction (r = 0.52 and -0.52, respectively) in the PUV group. On a multivariate analysis, the kidney dysfunction was the only independent predictor of vitamin D deficiency (ρ = 0.271, P < 0.001), while kidney dysfunction, serum calcium and alkaline phosphatase were independent predictors for hyperparathyroidism (ρ = 0.925, P<0.001, ρ = 0.933, P<0.001 and ρ = 0.913, P < 0.001, respectively).

DISCUSSION

The prevalence of CKD in children with PUVs ranges from 30 to 60%. Patients with CKD are more likely to have vitamin D deficiency and display more-prominent hyperparathyroidism. Compared with a control group with normal kidney function, the present cohort had lower 25-hydroxyvitamin D and higher iPTH serum levels. Abnormal kidney function was a major predictor for both serum levels. In this cohort, there were no significant differences in serum calcium and phosphorus between children with PUVs and the control group, and also between those with and without CKD. On the contrary, vitamin D level decreased early in the disease and progressively declined thereafter, while iPTH was the opposite. These findings were comparable to previous studies. This study had some limitations because it was a single center cross-sectional non-randomized study. However, the findings in this study can be extrapolated to children with PUVs and CKD from other origins because the unit is considered as a referral center in the Middle East region.

CONCLUSION

Abnormal kidney function, vitamin D deficiency, and secondary hyperparathyroidism are prevalent in children with PUVs. Kidney function is the main determinant of vitamin D and parathyroid hormone levels. Efforts should be directed toward managing CKD, and controlling vitamin D deficiency and hyperparathyroidism in children after ablation of PUV.

The neuroligin and neurexin families: from structure to function at the synapse

Proper brain connectivity and neuronal transmission rely on the accurate assembly of neurotransmitter receptors, cell adhesion molecules and several other scaffolding and signaling proteins at synapses. Several new exciting findings point to an important role for the neuroligin family of adhesion molecules in synapse development and function. In this review, we summarize current knowledge of the structure of neuroligins and neurexins, their potential binding partners at the synapse. We also discuss their potential involvement in several aspects of synapse development, including induction, specificity and stabilization. The implication of neuroligins in cognitive disorders such as autism and mental retardation is also discussed.

Renal transplantation in children with abnormal lower urinary tract

OBJECTIVE

This retrospective study reports the outcomes as well as pre- and posttransplant urologic treatments of renal transplantation for children with an abnormal lower urinary tract (LUT).

METHODS

Between March 1981 and December 2001, 195 children (< or =18 years of age) received live-donor kidney transplants. The 15 recipients (14 boys and 1 girl, mean age 13.5 +/- 3 years) who had lower urinary tract disorders included posterior urethral valves (PUV) with valve bladder (n=12) and neuropathic bladders secondary to meningomyelocele (n=3). These children were evaluated by voiding cystourethrogram, cystourethroscopy, and cystometry. The children with PUV were maintained on clean intermittent catheterization (CIC) and a detrusor relaxant at least 3 months before transplantation. Augmentation ileocystoplasty or continent cutaneous diversion were used in three patients. The graft and patient survivals as well as complications in this cohort was compared with a group of children with normal LUT, who underwent renal transplantation during the same period.

RESULTS

One child died in the early posttransplant period due to rupture of the external iliac artery. Follow-up ranged from 6 months to 16 years (mean=4.5 years). During the same period the graft and patient survival rates were comparable between the group of children with versus without abnormal LUT. Furthermore, mean serum creatinine and creatinine clearance values were also comparable. The group with an abnormal LUT showed a higher incidence of urinary fistula (3/14) and recurrent UTI and/or bacteremia (4/14).

CONCLUSIONS

Renal transplantation is feasible with good results for children with abnormal LUT. Pre- and posttransplant urologic management is critical for a successful outcome. However these children display a high incidence of urologic and infectious complications.