Post transplant erythrocytosis in hypercalcemic renal transplant recipients

Risk Factors for Posttransplant Erythrocytosis: Parathyroid Hormone Paradox?

OBJECTIVES

Posttransplant erythrocytosis affects 8% to 26% of kidney transplant recipients. In this study, our aim was to define associations among hypercalcemia, persistent hyperparathyroidism, and posttransplant erythrocytosis. We also investigated the effects of biologic sex, age, and dialysis modality before transplant on posttransplant erythrocytosis development.

MATERIALS AND METHODS

We enrolled 247 patients [159 (64%) male and 88 (36%) female] who underwent kidney transplant between 2009 and 2018. All demographic and laboratory parameters were retrospectively analyzed as possible factors associated with posttransplant erythrocytosis.

RESULTS

Fifty-nine (24%) of total patients had posttransplant erythrocytosis. The median time to posttransplant erythrocytosis development was 16 months (range, 8-34 mo). Male sex, the use of peritoneal dialysis as maintenance renal replacement therapy before kidney transplant, and persistent hyperparathyroidism were defined as independent risk factors for posttransplant erythrocytosis development in our multivariate logistic regression analyses (odds ratio = 5.228, 3.963, and 4.109, respectively). In addition, high serum creatinine levels were associated with a lower incidence of posttransplant erythrocytosis (odds ratio = 0.253). Although significance did not remain after multivariate analysis, hypercalcemia was found to be significantly associated with posttransplant erythrocytosis in univariate analyses (odds ratio = 1.768). In subgroup analyses, where only male patients were evaluated, persistent hyperparathyroidism and peritoneal dialysis were found to be independent risk factors for posttransplant erythrocytosis development (odds ratio = 4.176 and 5.003).

CONCLUSIONS

Persistent hyperparathyroidism and hypercalcemia could precipitate development of posttransplant erythrocytosis. The preserved residue renal function may be associated with increased endogenous erythropoietin, which could lead to posttransplant erythrocytosis development.

Risk factors and outcomes of post-transplant erythrocytosis among adult kidney transplant recipients: a systematic review and meta-analysis

Post-transplant erythrocytosis (PTE) can occur in up to 10-16% after kidney transplant (KT). However, the post-transplant outcomes of recipients with PTE in the literature were conflicting. We performed systematic review and meta-analysis of published studies to evaluate risk factors of PTE as well as outcomes of recipients who developed PTE compared with controls. A literature search was conducted evaluating all literature from existence through February 2, 2021, using MEDLINE and EMBASE. Data from each study were combined using the random-effects model. (PROSPERO: CRD42021230377). Thirty-nine studies from July 1982 to January 2021 were included (7,099 KT recipients). The following factors were associated with PTE development: male gender (pooled RR = 1.62 [1.38, 1.91], I²  = 39%), deceased-donor KT (pooled RR = 1.18 [1.03, 1.35], I²  = 32%), history of smoking (pooled RR = 1.36 [1.11, 1.67], I²  = 13%), underlying polycystic kidney disease (PKD) (pooled RR=1.56 [1.21, 2.01], I² =44%), and pretransplant dialysis (pooled RR=1.6 [1.02, 2.51], I² =46%). However, PTE was not associated with outcomes of interest, including overall mortality, death-censored graft failure, and thromboembolism. Our meta-analysis demonstrates that male gender, deceased-donor KT, history of smoking, underlying PKD, and pretransplant dialysis were significantly associated with developing PTE. However, with proper management, PTE has no impact on prognosis of KT patients.

FGF23 is associated with early post-transplant hypophosphataemia and normalizes faster than iPTH in living donor renal transplant recipients: a longitudinal follow-up study

Background

We aimed to longitudinally analyse changes in the levels of serum fibroblast growth factor 23 (FGF23), intact parathyroid hormone (iPTH) and associated minerals in patients undergoing renal transplantation.

Methods

Sixty-three patients with end-stage renal disease (ESRD) who underwent living donor transplantation were recruited. Serum FGF23, iPTH, uric acid, inorganic phosphorous (iP), blood urea nitrogen and serum creatinine were measured pre-transplant and at 1 (M1), 3 (M3) and 12 months (M12) post-transplantation.

Results

FGF23 levels were decreased at M1, M3 and M12 by 93.81, 96.74 and 97.53%, respectively. iPTH levels were decreased by 67.95, 74.95 and 84.9%, respectively. The prevalence of hyperparathyroidism at M1, M3 and M12 post-transplantation was 63.5, 42.9 and 11.1%, respectively. FGF23 and iP levels remained above the normal range in 23 (36.5%) and 17 (27%) patients at M1, 10 (15.9%) and 5 (8%) at M3 and in none at M12 post-transplantation, respectively. A multivariate regression model revealed that, pre-transplant, iP was positively associated with iPTH (P = 0.016) but not with FGF 23; however, post-transplant, iP level was negatively associated with FGF23 (P < 0.001) but not with iPTH.

Conclusions

Post-transplant FGF23 levels settle faster than those of iPTH. However, 11% of patients continued to have hyperparathyroidism even after 12 months.

Clinical impact of hypercalcemia in kidney transplant

Hypercalcemia (HC) has been variably reported in kidney transplanted (KTx) recipients (5–15%). Calcium levels peak around the 3rd month after KTx and thereafter slightly reduce and stabilize. Though many factors have been claimed to induce HC after KTx, the persistence of posttransplant hyperparathyroidism (PT-HPT) of moderate-severe degree is universally considered the first causal factor. Though not proven, there are experimental and clinical suggestions that HC can adversely affect either the graft (nephrocalcinosis) and other organs or systems (vascular calcifications, erythrocytosis, pancreatitis, etc.). However, there is no conclusive evidence that correction of serum calcium levels might avoid the occurrence of these claimed clinical effects of HC. The best way to reduce the occurrence of HC after KTx is to treat as best we can the secondary hyperparathyroidism (SHP) during the uraemic stages. The indication to Parathyroidectomy (PTX), either before or after KTx, in order to prevent or to treat, respectively, HC after KTx, is still a matter of debate which has been revived by the availability of the calcimimetic cinacalcet for the treatment of PT-HPT. However, we still need to better clarify many points as regards the potential adverse effects related to either PTX or cinacalcet use in this clinical set, and we are waiting for the results of future randomized controlled trials to achieve some more definite conclusions on this topic.

KDIGO clinical practice guideline for the care of kidney transplant recipients

The 2009 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline on the monitoring, management, and treatment of kidney transplant recipients is intended to assist the practitioner caring for adults and children after kidney transplantation. The guideline development process followed an evidence-based approach, and management recommendations are based on systematic reviews of relevant treatment trials. Critical appraisal of the quality of the evidence and the strength of recommendations followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. The guideline makes recommendations for immunosuppression, graft monitoring, as well as prevention and treatment of infection, cardiovascular disease, malignancy, and other complications that are common in kidney transplant recipients, including hematological and bone disorders. Limitations of the evidence, especially on the lack of definitive clinical outcome trials, are discussed and suggestions are provided for future research.

Cinacalcet chloride is efficient and safe in renal transplant recipients with posttransplant hyperparathyroidism

BACKGROUND

Persistent hyperparathyroidism (HPT) is observed in approximately 50% of kidney transplant recipients one year after transplantation. It may result in hypercalcemia, hypophosphatemia, bone demineralization, vascular calcification, lithiasis, and participate in chronic allograft nephropathy. We evaluated the use of the calcimimetic cinacalcet chloride to correct chronic hypercalcemia in posttransplant HPT, in a prospective single-center study.

METHODS

Nine patients with persistent hypercalcemia (>2.6 mmol/L) and stable graft function were treated with cinacalcet (30 mg/day, thereafter adapted to obtain normal serum Ca levels) for six months. Their immunosuppressive schedule included mycophenolate mofetil (MMF), steroids, and cyclosporine A (4), tacrolimus (4), or sirolimus (2).

RESULTS

Serum Ca levels significantly decreased from 2.75+/-0.15 to 2.59+/-0.10, 2.42+/-0.29 and 2.44+/-0.25 mmol/L by one, two, and six months, respectively (P<0.02, Wilcoxon test for paired data, for all the data points). Parathyroid hormone (PTH) serum levels decreased from 171+/-102 to 134+/-63 pg/ml by two months (P<0.05) and stabilized thereafter (148+/-99 pg/ml at six months; NS). No changes in glomerular filtration rate (49.8+/-18.6 and 51.3+/-19 ml/min at initiation and six months, respectively) and no variation in serum concentration of the immunosuppressive drugs were observed. Three patients withdrew the treatment because gastrointestinal intolerance.

CONCLUSION

Cinacalcet allows the correction of hypercalcemia with no interference in immunosuppressive treatment or renal function. However, whether the increased intolerance observed was due to the association of cinacalcet chloride with other drugs required in renal transplantation (e.g., MMF) needs to be assessed.

Hormonal adjuvants for the treatment of renal anaemia

Hormonal adjuvants, besides being erythropoietic agents, broaden the spectrum of therapeutic options for the treatment of the anaemia of chronic kidney disease (CKD). Lowering elevated parathyroid hormone levels by oral calcium supplementation and phosphate restriction, by varying dialysate calcium concentrations, by administration of vitamin D3 derivatives and, in the near future, by treatment with calcimimetics may prove efficient in some patients to fight extensive requirements of erythropoietic agents. Clinical evidence for a principal role of secondary hyperparathyroidism in resistance to erythropoietin, however, is lacking. Active vitamin D3 derivatives, in addition to their beneficial effects on secondary hyperparathyroidism, appear to exert a direct, stimulatory action on erythroid precursor cells and possibly also an inhibitory action on collagen synthesis by bone marrow stromal cells. Growth hormone (GH) induces insulin-like growth factor (IGF)-1, which in turn counteracts apoptosis similarly to erythropoietin, and fosters proliferation of burst- and colony-forming units-erythroid (BFU-E, CFU-E). If erythropoietic agents improve survival of CKD patients, a similar benefit should apply for strategies that increase synthesis and bioavailabilty of IGF-1. The latter appears to be reduced in CKD patients, and zinc supplementation potentially enhances it via an increase in free IGF-1. Finally, androgens also exert anti-anaemic effects. Nandrolone decanoate constitutes the only androgen currently applicable for selected male dialysis patients over the age of 50 years. It should not be given to women, however, because of serious side effects. Collectively, hormonal interventions offer the potential to reduce requirements of erythropoietic agents, and some may also improve physical performance.

Relationship of Posttransplantation Erythrocytosis to Hypercalcemia in Renal Transplant Recipients

Experimental studies have demonstrated that calcium is an essential molecule in modulation of erythropoiesis. The aim of this study was to investigate the role of serum calcium levels on the development of posttransplantation erythrocytosis (PTE) among renal transplant recipients. We enrolled 155 patients (36 females/119 males; mean age, 34.9 +/- 9.7 years) with normal graft function who underwent renal transplantation between 1999 and 2002. All of the demographic features and various laboratory parameters were retrospectively analyzed as possible factors associated with erythrocytosis. PTE appeared in 43 (27.7%) patients during the follow-up period. Sixty-three (40.6%) patients developed hypercalcemia (corrected serum calcium level > or =10.2 mg/dL). Serum calcium levels tended to increase in patients with PTE, but significantly decreased in patients without PTE (10.6 +/- 0.6 vs 9.8 +/- 0.5 mg/dL; P < .0001). Similarly, hypercalcemia was more common among patients with PTE compared with patients without PTE (74.4% vs 27.7%; P < .0001). Hypercalcemic patients had a significantly higher frequency of PTE than normocalcemic patients (50.7% vs 11.9%; P < .0001). There were no differences in other laboratory and demographic data between the patients with and without PTE (P > .05). These findings suggest that hypercalcemia may lead to increased PTE in renal transplant recipients.