Update of the recommendations on the management of the SARS-CoV-2 coronavirus pandemic (COVID-19) in kidney transplant patients.

SARS-CoV-2 infection (COVID-19) has had a significant impact on transplant activity in our country. Mortality and the risk of complications associated with COVID-19 in kidney transplant recipients (KT) were expected to be higher due to their immunosuppressed condition and the frequent associated comorbidities. Since the beginning of the pandemic in March 2020 we have rapidly improved our knowledge about the epidemiology, clinical features and management of COVID-19 post-transplant, resulting in a better prognosis for our patients. KT units have been able to adapt their programs to this new reality, normalizing both donation and transplantation activity in our country. This manuscript presents a proposal to update the general recommendations for the prevention and treatment of infection in this highly vulnerable population such as KT.

[Update of the recommendations on the management of the SARS-CoV-2 coronavirus pandemic (COVID-19) in kidney transplant patients.] / Actualización de las recomendaciones en el manejo de la pandemia por coronavirus SARS-CoV-2 (COVID-19) en pacientes con trasplante renal.

SARS-CoV-2 infection (COVID-19) has had a significant impact on transplant activity in our country. Mortality and the risk of complications associated with COVID-19 in kidney transplant recipients (KT) were expected to be higher due to their immunosuppressed condition and the frequent associated comorbidities. Since the beginning of the pandemic in March 2020 we have rapidly improved our knowledge about the epidemiology, clinical features and management of COVID-19 post-transplant, resulting in a better prognosis for our patients. KT units have been able to adapt their programs to this new reality, normalizing both donation and transplantation activity in our country.This manuscript presents a proposal to update the general recommendations for the prevention and treatment of infection in this highly vulnerable population such as KT.

Silver jubilee: 25 years of the first demonstration of the direct effect of phosphate on the parathyroid cell.

Although phosphorus is an essential element for life, it is not found in nature in its native state but rather combined in the form of inorganic phosphates (PO43-), with tightly regulated plasma levels that are associated with deleterious effects and mortality when these are out of bounds. The growing interest in the accumulation of PO43- in human pathophysiology originated in its attributed role in the pathogenesis of secondary hyperparathyroidism (SHPT) in chronic kidney disease. In this article, we review the mechanisms by which this effect was justified and we commemorate the important contribution of a Spanish group led by Dr. M. Rodríguez, just 25 years ago, when they first demonstrated the direct effect of PO43- on the regulation of the synthesis and secretion of parathyroid hormone by maintaining the structural integrity of the parathyroid glands in their original experimental model. In addition to demonstrating the importance of arachidonic acid (AA) and the phospholipase A2-AA pathway as a mediator of parathyroid gland response, these findings were predecessors of the recent description of the important role of PO43- on the activity of the calcium sensor-receptor, and also fueled various lines of research on the importance of PO43- overload not only for the pathophysiology of SHPT but also in its systemic pathogenic role.

Dual corneal involvement by endothelial and epithelial corneal dystrophies in Steinert's disease: A case of triple dystrophy.

INTRODUCTION: A case of dual corneal involvement due to Fuchs endothelial corneal dystrophy and epithelial basement membrane corneal dystrophy in a patient with Steinert's myotonic dystrophy type 1 is described, and a literature review on the triple association is made. CASE DESCRIPTION: A 52-year-old male diagnosed with myotonic dystrophy type 1 presented due to progressive bilateral vision loss during the past year. A full ophthalmological evaluation was made, with biomicroscopy, funduscopy, anterior segment optical coherence tomography, and endothelial cell count using specular microscopy. Exploration revealed bilateral superior palpebral ptosis, visual acuity 0.5 in the right eye and 0.3 in the left eye, and with an intraocular pressure of 11 and 10 mmHg, respectively. Biomicroscopy revealed map-dot-fingerprint lesions characteristic of epithelial basement membrane corneal dystrophy in both eyes, as well as abundant endothelial guttae due to Fuchs endothelial corneal dystrophy (stage II) and bilateral nuclear and posterior subcapsular cataracts. Specular microscopy in turn showed cell loss and a destructured endothelial map. Finally, anterior segment optical coherence tomography revealed the accumulation of epithelial basement membrane and hyperreflective endothelial excrescences corresponding to guttae. CONCLUSION: The association of Fuchs endothelial corneal dystrophy with myotonic dystrophy has been described and explained by a common genetic basis in the expansion of a CTG trinucleotide repeat, though this is the first reported case of the triple association of Fuchs endothelial corneal dystrophy, epithelial basement membrane corneal dystrophy, and myotonic dystrophy type 1. New mutations or still unknown genetic alterations could possibly explain the triple association reported in our case.

[Recommendations on management of the SARS-CoV-2 coronavirus pandemic (Covid-19) in kidney transplant patients]. / Recomendaciones en el manejo de la pandemia por coronavirus SARS-CoV-2 (Covid-19) en pacientes con trasplante renal.

The SARS-CoV-2 (Covid-19) coronavirus pandemic is evolving very quickly and means a special risk for both immunosuppressed and comorbid patients. Knowledge about this growing infection is also increasing although many uncertainties remain, especially in the kidney transplant population. This manuscript presents a proposal for action with general and specific recommendations to protect and prevent infection in this vulnerable population such as kidney transplant recipients.

Impact of vitamin D dose on biochemical parameters in patients with secondary hyperparathyroidism receiving cinacalcet.

BACKGROUND/AIMS: The calcimimetic cinacalcet (Mimpara/Sensipar) simultaneously lowers parathyroid hormone (PTH), phosphorus (P) and calcium (Ca) levels in patients with secondary hyperparathyroidism. The OPTIMA study demonstrated that cinacalcet and adjusted doses of vitamin D maximized control of these parameters. This post-hoc analysis of OPTIMA data assessed the impact of reducing or increasing the dose of concomitant vitamin D on PTH, P and Ca in patients receiving cinacalcet. METHODS: Dialysis patients with mean baseline intact PTH (iPTH) 300-800 pg/ml (31.8-84.8 pM) received doses of cinacalcet titrated to achieve an iPTH of 150-300 pg/ml (15.9-31.8 pM). The dose of vitamin D could then be decreased to further reduce serum P or Ca, or increased/initiated to further decrease PTH levels if iPTH >300 pg/ml or to increase Ca if Ca <8.0 mg/dl (2.0 mM). RESULTS: Vitamin D dose was assessed for 345 patients during a 23-week period. A total of 91 and 129 patients had an increase or decrease in vitamin D dose, respectively. By study end, mean iPTH, P, and Ca were similar in both vitamin D groups, although there were differences in biochemical parameters between groups at the start of the study. There were statistically significant reductions from baseline to study end in iPTH and Ca in both groups (p < 0.001). Although P was significantly reduced by week 23 in the group in which vitamin D dose was decreased (p = 0.007), the reduction in P was less and did not achieve significance in the group in which vitamin D dose was increased (p = 0.71). CONCLUSIONS: After initiating cinacalcet, the dose of vitamin D can be adjusted to maximize reductions in PTH, P and Ca; however, vitamin D-induced decreases in PTH need to be balanced with the diminished response in P and Ca.

Consequences of the implementation of K/DOQI Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease in a population of patients on chronic hemodialysis.

BACKGROUND: After application of K/DOQI recommendations, a large proportion of our patients failed to reach the proposed targets. This study examined the causes of these findings. METHODS: Patients (n=163) were compared in 2 periods (8 months before and after application of K/DOQI guidelines). Serum calcium (Ca), phosphorus (P), parathyroid hormone (PTH) and calcium x phosphate product (Ca x P); mean dialysate Ca content; mean doses of vitamin D; and average prescription of Ca-based phosphate binders and sevelamer in both periods were analyzed. RESULTS: Prescription of Ca salts as phosphate-binding agents decreased and prescription of sevelamer increased in an attempt to maintain serum Ca levels between 8.4 and 9.5 mg/dL post-K/DOQI. Increased serum PTH levels were associated with decreased serum Ca levels (relative risk [RR] = 41.1, p<0.001) and increased serum P levels (RR=6.81, p<0.01). Use of dialysis fluids with Ca content of 2.5 mEq/L was associated with an increased risk of having PTH levels >300 pg/mL (RR=11.4, p<0.003). Vitamin D metabolites had to be discontinued in 26 patients (37.1% of those receiving them from study start) due to hyperphosphoremia or hypercalcemia post-K/DOQI; and serum PTH significantly increased (445.8 +/- 238.2 pg/mL vs. 715.2 +/- 549.5 pg/mL; p<0.001). Ninety-three patients (57%) did not receive vitamin D at study start; in 20 of those (21.5%), vitamin D had to be started post-K/DOQI. CONCLUSIONS: Clinical guidelines do not appear to be sufficient to overcome all difficulties arising in daily management of these patients.

C.E.R.A. administered once monthly corrects and maintains stable hemoglobin levels in chronic kidney disease patients not on dialysis: the observational study MICENAS II.

BACKGROUND AND OBJECTIVE: C.E.R.A. (continuous erythropoietin receptor activator, pegilated-rHuEPO ß) corrects and maintains stable hemoglobin levels in once-monthly administration in chronic kidney disease (CKD) patients. The aim of this study was to evaluate the management of anemia with C.E.R.A. in CKD patients not on dialysis in the clinical setting. METHODS: Two hundred seventy two anemic CKD patients not on dialysis treated with C.E.R.A. were included in this retrospective, observational, multicentric study during 2010. Demographical characteristics, analytical parameters concerning anemia, treatment data and iron status were recorded. RESULTS: C.E.R.A. achieved a good control of anemia in both naïve patients (mean Hemoglobin 11.6g/dL) and patients converted from a previous ESA (mean Hemoglobin 11.7g/dL). Most naïve patients received C.E.R.A. once monthly during the correction phase and required a low monthly dose (median dose 75 µg/month). The same median dose was required in patients converted from a previous ESA, and it was lower than recommended in the Summary of Product Characteristics (SPC). Iron status was adequate in 75% of anemic CKD patients, but only 50% of anemic patients with iron deficiency received iron supplementation. CONCLUSIONS: C.E.R.A. corrects and maintains stable hemoglobin levels in anemic CKD patients not on dialysis, requiring conversion doses lower than those recommended by the SPC, and achieving target hemoglobin levels with once-monthly dosing frequency both in naïve and converted patients.

Response of parathyroid glands to calcitriol in culture: Is this response mediated by the genetic polymorphisms in vitamin D receptor?

BACKGROUND: Recently, we have developed a model of parathyroid tissue culture that allows the study of the response of the parathyroid glands to long-term effectors, such as calcitriol, and that is also useful to study the likely effect of the genetic polymorphisms in the functionality of the glands. The aim of this study was to evaluate the response to calcitriol of cultured parathyroid tissue from patients with secondary hyperparathyroidism (HPT) and the possible effect of vitamin D receptor (VDR) gene polymorphisms on this response. METHODS: Parathyroid glands (N = 37) from 34 parathyroidectomized patients (17 men, 17 women) were used. Several gland fragments were cultured for 60 hours in the presence of calcitriol 10(-9) mol/L or 10(-8) mol/L. DNA from each fragment was extracted to normalize the hormone secretion levels and to genotype the restriction sites ApaI, BsmI, TaqI, and FokI in the VDR gene. RESULTS: The percentages of secretion observed in the response to calcitriol were: 69%+/- 28% (range, 3-100) and 46%+/- 19% (range, 8-78) for calcitriol 10(-9) mol/L and 10(-8) mol/L, respectively (P = 0.004). None of the polymorphisms showed statistical differences in response to calcitriol with any of the concentrations used. CONCLUSION: Parathyroid glands cultured in vitro from patients with secondary HPT are able to respond to calcitriol decreasing PTH synthesis. These results, however, do not support the current hypothesis that VDR polymorphisms are involved in the modulation of the parathyroid gland response.

A lower proportion of circulating active parathyroid hormone in peritoneal dialysis does not allow the pth inter-method adjustment proposed for haemodialysis.

INTRODUCTION: Parathyroid hormone (PTH) shows a strong correlation with histomorphometric and biochemical parameters of bone turnover, however its measurement presents limitations due to inter-method variability. Circulating PTH is a mixture of peptides, but only on its whole form (1-84 PTH) is responsible of PTH biological activity. Carboxyl-terminal fragments exhibit antagonist actions and their proportion differs at each stage of chronic kidney disease, as consequence of differences on their renal clearance. The aim of this study is to evaluate possible differences in the proportion of these fragments according to dialysis type: haemodialysis (HD) or peritoneal dialysis (PD). MATERIAL AND METHODS: Serum total (Ca) and ionized calcium (iCa), phosphate (P), carboxyl-terminal telopeptides of collagen type I (BCTx) were measured in 73 patients on PD (46 men and 27 women with an age between 22 and 82 years). PTH was quantified by six second generation assays (one isotopic and five chemiluminescence assays) and by one third generation PTH method. RESULTS: Mean serum levels of Ca, iCa, P and BCTx were 9.03, 4.76, 4.73 mg/dl and 1181 pmol/l, respectively. Significant differences were observed in PTH values according to the method used. Adjustment of PTH results to PTH Allegro (Nichols) range of 150-300 nmol/l in PD patients showed higher values than those assessed previously for HD population. The percentage of biologically active 1-84 PTH as the 1-84 PTH/ 7-84 PTH ratio in PD were significantly lower than in HD patients, reflecting the higher proportion of 7-84 PTH circulating fragments for a given intact PTH result in PD. CONCLUSIONS: PD patients have a higher proportion of 7-84 PTH circulating fragments. Consequently, the inter-method adjustment algorithms proposed for HD patients are not useful for PD patients. This study proposes alternative algorithms for PTH inter-method adjustment to be applied in PD.

The OPTIMA study: assessing a new cinacalcet (Sensipar/Mimpara) treatment algorithm for secondary hyperparathyroidism.

BACKGROUND AND OBJECTIVES: Cinacalcet, a novel calcimimetic, targets the calcium-sensing receptor to lower parathyroid hormone (PTH), calcium, and phosphorus levels in dialysis patients with secondary hyperparathyroidism (SHPT). This study compared the efficacy of a cinacalcet-based regimen with unrestricted conventional care (vitamin D and phosphate binders) for achieving the stringent National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI) targets for dialysis patients. STUDY DESIGN: In this multicenter, open-label study, hemodialysis patients with poorly controlled SHPT were randomized to receive conventional care (n = 184) or a cinacalcet-based regimen (n = 368). Doses of cinacalcet, vitamin D sterols, and phosphate binders were adjusted during a 16-wk dose-optimization phase with the use of algorithms that allowed cinacalcet to be used with adjusted doses of vitamin D. The primary end point was the proportion of patients with mean intact PTH < or =300 pg/ml during a 7-wk efficacy assessment phase. RESULTS: A higher proportion of patients receiving the cinacalcet-based regimen versus conventional care achieved the targets for PTH (71% versus 22%, respectively; P < 0.001), Ca x P (77% versus 58%, respectively; P < 0.001), calcium (76% versus 33%, respectively; P < 0.001), phosphorus (63% versus 50%, respectively; P = 0.002), and PTH and Ca x P (59% versus 16%, respectively, P < 0.001), and allowed a 22% reduction in vitamin D dosage in patients receiving vitamin D at baseline. Achievement of targets was greatest in patients with less severe disease (intact PTH range, 300 to 500 pg/ml) and the cinacalcet dose required was lower in these patients (median = 30 mg/d). CONCLUSIONS: Compared with conventional therapy, a cinacalcet-based treatment algorithm increased achievement of KDOQI treatment targets in dialysis patients in whom conventional therapy was no longer effective in controlling this disease.

The in vitro effect of calcitriol on parathyroid cell proliferation and apoptosis.

Calcitriol treatment is used to reduce parathyroid hormone levels in azotemic patients with secondary hyperparathyroidism (HPT). Whether long-term calcitriol administration reduces parathyroid gland size in patients with severe secondary hyperparathyroidism is not clear. The aim of the study was to evaluate in vitro the effect of calcitriol on parathyroid cell proliferation and apoptosis in normal parathyroid glands and in adenomatous and hyperplastic human parathyroid glands. Freshly harvested parathyroid glands from normal dogs and hyperplastic and adenomatous glands from patients with secondary (2 degrees) and primary (1 degree) HPT undergoing parathyroidectomy were studied. Flow cytometry was used to quantify the cell cycle and apoptosis of parathyroid cells. Apoptosis was also evaluated by DNA electrophoresis and light and electron microscopy. In normal dog parathyroid glands, culture with calcitriol (10(-10) to 10(-7) M) for 24 h produced a dose-dependent inhibitory effect on the progression of cells into the cell cycle and into apoptosis. When glands from patients with 2 degrees HPT were cultured for 24 h, only high calcitriol concentrations (10(-7) M) inhibited the progression through the cell cycle and the induction of apoptosis. In parathyroid adenomas (1 degrees HPT), even a high concentration of calcitriol (10(-7) M) had no significant effect on the cell cycle or apoptosis. The present study shows that in vitro, calcitriol inhibits in a dose-dependent manner in normal parathyroid glands both parathyroid cell proliferation and apoptosis. However, in secondary hyperplasia, only high concentrations of calcitriol inhibited cell proliferation and apoptosis. In 1 degree HPT, even high concentrations of calcitriol had no effect. Because calcitriol simultaneously inhibits both cell proliferation and apoptosis, a reduction in the parathyroid gland mass may not occur as a direct effect of calcitriol treatment.

Proliferation in hyperplastic human and normal rat parathyroid glands: role of phosphate, calcitriol, and gender.

BACKGROUND: Parathyroid gland hyperplasia develops in azotemic patients. A phosphate excess and calcitriol deficiency play critical roles in its development. Our goals were to determine whether differences in serum phosphate values at parathyroidectomy (PTX) in hemodialysis patients with refractory hyperparathyroidism: (1) correlated with parathyroid cell proliferation; and (2) affected the antiproliferative response to in vitro calcitriol. Studies were also performed to determine whether the phosphate concentration in the medium affected the antiproliferative response to calcitriol, and whether a high phosphate diet and calcitriol treatment affected parathyroid cell proliferation and parathyroid hormone (PTH) levels in normal rats. METHODS: Forty-seven parathyroid glands from 19 hemodialysis patients were obtained at PTX. Flow cytometry was used to determine cell proliferation (percent cells in S phase) in excised parathyroid glands. Similarly, cell proliferation was determined in parathyroid tissue incubated for 24 hours in medium with or without 10(-7) mol/L calcitriol and with 1 or 4 mmol/L phosphate. In normal rats, the effect of 3 days of a high phosphate diet (1.2% P) and calcitriol treatment (100 pmol/kg) on PTH values and cell proliferation was evaluated. RESULTS: In cells from freshly removed parathyroid glands obtained at PTX from hemodialysis patients, there were no significant correlations between the percent cells in S phase and age, gender, and serum phosphate, calcium, and PTH. While incubation of parathyroid tissue with 10(-7) mol/L calcitriol did reduce cell proliferation (P < 0.001), both the pre-PTX serum phosphate value (P= 0.003) and female gender (P=0.003) were associated with a decreased response to calcitriol. Incubation of parathyroid tissue in medium containing 4 mmol/L phosphate did not increase cell proliferation. In normal rats, a high phosphate diet for 3 days increased cell proliferation (P < 0.05) and PTH levels (P < 0.05), and calcitriol treatment was without effect. CONCLUSION: Our findings suggest a high phosphate burden, as well as female gender, favor parathyroid cell proliferation and both may reduce the inhibition of parathyroid function by calcitriol.