Magnesemia in Renal Transplant Recipients: Relation With Immunosuppression and Posttransplant Diabetes

Pancreatic steatosis is an independent risk factor for post-transplant diabetes mellitus in kidney transplant patients

BACKGROUND AND AIM

Post-transplant diabetes mellitus (PTDM) is associated with an increased risk of post-transplant cardiovascular diseases, and several risk factors of PTDM have been shown in the literature. Yet, the relationship between hepatic and pancreatic steatosis with post-transplant diabetes mellitus remains vague. We aimed to evaluate pancreatic steatosis, a novel component of metabolic syndrome, and hepatic steatosis association with post-transplant diabetes mellitus in a single-center retrospective cohort study conducted on kidney transplant recipients.

METHOD

We have performed a single-center retrospective cohort study involving all kidney transplant recipients. We have utilized pretransplant Fibrosis-4, nonalcoholic fatty liver disease fibrosis score, and abdominal computed tomography for the assessment of visceral steatosis status.

RESULTS

We have included 373 kidney transplant recipients with a mean follow-up period of 32 months in our final analysis. Post-transplant diabetes mellitus risk is associated with older age (p < .001), higher body-mass index (p < .001), nonalcoholic fatty liver disease-fibrosis score (p = .002), hepatic (p < .001) or pancreatic (p < .001) steatosis on imaging and higher pre-transplant serum triglyceride (p = .003) and glucose levels (p = .001) after multivariate analysis.

CONCLUSION

Our study illustrates that recipients' pancreatic steatosis is an independent predictive factor for post-transplant diabetes mellitus including in kidney transplant patients.

Is Serum Magnesium Level Associated With Serum Lipid Levels in Kidney Transplant Recipients?

BACKGROUND

Magnesium (Mg) is key in diabetes mellitus, hyperlipidemia, and cardiovascular disease.

METHODS

This is a retrospective cross-sectional study including 103 kidney transplant recipients. Patients aged under 18 years, patients treated with Mg supplementation, antihyperlipidemic agents, or diuretics, and patients with active infection or malignancy were not enrolled. Patients were divided into 2 groups according to median serum Mg level. The atherogenic index of plasma was calculated by a logarithmic transformation of the number acquired by dividing the molar concentrations of serum triglyceride by high-density lipoprotein value.

RESULTS

The mean serum Mg level was 1.91 ± 0.28 mg/dL. Six patients (5.8%) had hypomagnesemia (Mg <1.5 mg/dL), and 2 (1.9%) had hypermagnesemia (Mg >2.6 mg/dL). Serum Mg level was negatively correlated with body mass index, estimated glomerular filtration rate (eGFR), and tacrolimus trough level and positively correlated with levels of phosphorus, total cholesterol, and low-density lipoprotein (LDL-C). There was no correlation between serum Mg and triglyceride, high-density lipoprotein, atherogenic index of plasma, and cyclosporin A trough level. Patients with Mg >1.87 mg/dL had lower eGFR, tacrolimus, and cyclosporin A trough level and higher total cholesterol and LDL-C compared to those with Mg ≤1.87 mg/dL. In adjusted ordinal analysis, eGFR (hazard ratio (HR): 0.981, 95% CI 0.964-0.999, P = .036) and total cholesterol (HR: 1.015, 95% CI 1.004-1.027, P = .008) were independently associated with serum Mg. In multivariate linear regression analysis, serum Mg level was independently associated with LDL-C (β = .296, t = 3.079, P = .003) and total cholesterol (β = .295, t = 3.075, P = .003).

CONCLUSION

Serum Mg level may have an important impact on dyslipidemia in kidney transplant recipients.

Acquired Disorders of Hypomagnesemia

Magnesium disorders are common in clinical practice and when present can manifest clinically as cardiovascular, neuromuscular, or other organ dysfunction. Hypomagnesemia is far more common than hypermagnesemia, which is largely seen in patients with reduced glomerular filtration rates receiving magnesium-containing medications. In addition to inherited disorders of magnesium handling, hypomagnesemia is also seen with excessive gastrointestinal or renal losses and due to medications such as amphotericin B, aminoglycosides, and cisplatin. Laboratory assessment of body magnesium stores largely relies on the measurement of serum magnesium levels that are a poor proxy for total body stores but does correlate with the development of symptoms. Replacement of magnesium can be challenging, with oral replacement strategies being generally more effective at slowly replacing body stores but intravenous replacement being more effective at treating the more life-threatening and severe cases of hypomagnesemia. We conducted a thorough review of the literature using PubMed (1970-2022) and the search terms magnesium, hypomagnesemia, drugs, medications, treatment, and therapy. In the absence of clear data on optimal management of hypomagnesemia, we have made recommendations on magnesium replacement based on our clinical experience.

Impact of Post-Transplantation Hypomagnesemia on Long-Term Graft and Patient Survival after Transplantation

BACKGROUND

Post-transplant hypomagnesemia is commonly observed among patients prescribed calcineurin inhibitor (CNIs).

METHODS

We conducted a retrospective single-center analysis (2000-2013, N = 726) to examine the association of hypomagnesemia with long-term patient and allograft outcomes in kidney transplant recipients. A median serum magnesium (Mg) level of all measured Mg levels from 1 month to 1 year posttransplant was calculated.

RESULTS

For every increase in Mg of 0.1 mg/dL, the risk for either graft loss or death, overall mortality, and death with a functioning graft increased by 11%, 14%, and 12%, respectively (p < 0.01). In a multivariate model, patients with median Mg level ≥1.7 mg/dL had a reduced overall survival rate (HR 1.57, 95% CI: 1.04-2.38, p = 0.033) compared to those with median Mg level <1.7 mg/dL. This association was observed in subgroups of patients above 60 years old, in those who had a slow graft function (SGF) and in females.

CONCLUSIONS

Posttransplant hypomagnesemia is associated with better patient and allograft survival up to 10 years posttransplant. This relationship remained significant after accounting for baseline allograft function, presence of SGF and CNI trough levels.

Risk Factors of the Development of Diabetes Mellitus After Kidney Transplantation

BACKGROUND

The occurrence of diabetes mellitus is common after kidney transplantation (posttransplant diabetes mellitus [PTDM]) and enhances the cardiovascular risk and risk for kidney graft loss. The incidence of PTDM is about 5% to 40%. This study aimed to examine the potential risk factors that determine the occurrence of PTDM.

METHODS

This study retrospectively included 298 patients from transplantation unit of Evangelismos who underwent kidney transplantation during a 10-year period (January 1, 2009, to January 1, 2019). Kidney transplant recipients with diabetes mellitus prior to transplantation or those with follow-up of <6 months were rejected from the study. In total, the study included 274 recipients with a mean age of 50 ± 18 years. The mean time of monitoring was 63 ± 18 months. The PTDM diagnosis was based on the 2018 criteria of the American Diabetes Association.

RESULTS

Of 274 kidney transplant recipients, PTDM developed in 38 (13.8%) patients over a period of 11 ± 9 months after transplantation. Given that immunosuppressive therapy was identical in most patients, statistical analysis did not correlate the incidence of diabetes with treatment. However, there was a correlation for the occurrence of PTDM between the presence of hypomagnesemia and increased uric acid levels. Finally, there was a negative correlation between the age of the recipient and the time of PTDM onset.

CONCLUSION

Hypomagnesemia and hyperuricemia increased the risk of PTDM in these patients. Given the association between hypomagnesemia and the development of diabetes mellitus after kidney transplantation, prospective studies are needed to identify the causes of PTDM and to develop prevention strategies.

Longitudinal Assessment of Electrolyte Disorders in a Cohort of Chronic Stable Kidney Transplant Recipients

BACKGROUND

Kidney transplantation is complicated by various electrolyte disturbances with variable reported prevalence and incidence and of multifactorial pathogenesis. The aim of our study was the retrospective longitudinal assessment of the serum electrolytes in a cohort of stable kidney transplant recipients (KTRs) and the possible associated parameters, including graft function and medications.

METHODS

We included 93 stable KTRs under follow-up in our hospital's kidney transplant unit. Serum magnesium, calcium, phosphorus, potassium, sodium, and urine sodium levels were recorded retrospectively during 3 consecutive years. In addition, comorbidities, biochemical parameters, medications, and graft function (estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration equation and 24-hour urinary protein [uTpr]) were recorded.

RESULTS

Mean age at baseline was 51 ± 11 years; 64 KTRs were men (68.8%), 17 (18.3%) had diabetes, 79 (85%) had hypertension, and 11 (11.8%) had cardiovascular disease. Mean eGFR and uTpr (mg/24 h) at study initiation were 47.1 ± 13.5 mL/min/1.73 m² and 369.4 ± 404.2 mg/24 h, respectively. Hypomagnesemia was the most common disturbance observed in 21.7% of KTRs. Patients with hypomagnesemia displayed higher parathyroid hormone levels and more frequently had diabetes. Hypophosphatemia was recorded in 9.7% of KTRs during the first year. Hyperkalemia, hypokalemia, and hypercalcemia were rare (<5%). Mean serum and urine sodium concentration remained stable during the study, whereas urinary sodium levels showed a positive correlation with uTpr (P < .05).

CONCLUSIONS

In our cohort of KTRs, there were no significant electrolyte disorders, either in terms of frequency or severity, with hypomagnesemia being the most prevalent disturbance. The identification of potential associated risk factors and clinical data correlations are pivotal for the development of individualized and evidence-based therapeutic approach and decisions.

An overview of diagnosis and management of drug-induced hypomagnesemia

Magnesium (Mg) is commonly addressed as the "forgotten ion" in medicine. Nonetheless, hypomagnesemia should be suspected in clinical practice in patients with relevant symptomatology and also be considered a predisposing factor for the development of other electrolyte disturbances. Furthermore, chronic hypomagnesemia has been associated with diabetes mellitus and cardiovascular disease. Hypomagnesemia as a consequence of drug therapy is relatively common, with the list of drugs inducing low serum Mg levels expanding. Culprit medications linked to hypomagnesemia include antibiotics (e.g. aminoglycosides, amphotericin B), diuretics, antineoplastic drugs (cisplatin and cetuximab), calcineurin inhibitors, and proton pump inhibitors. In recent years, the mechanisms of drug-induced hypomagnesemia have been unraveled through the discovery of key Mg transporters in the gut and kidney. This narrative review of available literature focuses on the pathogenetic mechanisms underlying drug-induced hypomagnesemia in order to increase the insight of clinicians toward early diagnosis and effective management.

The Association Between Exposure to Low Magnesium Blood Levels After Renal Transplantation and Cardiovascular Morbidity and Mortality

Background: Serum magnesium levels are associated with cardiovascular disease and all-cause mortality in the general population and chronic kidney disease patients, but the association between serum magnesium levels and cardiovascular risk after kidney transplantation is not established. We sought to evaluate whether exposure to low serum magnesium levels after renal transplantation is related to cardiovascular morbidity and mortality.

Methods: We conducted a single center retrospective study that included all transplanted patients who had a functioning graft for at least 6 months after transplantation between January 2001 and December 2013. We calculated exposure to magnesium using time weighted average for serum magnesium levels, using all values available during the follow-up. Several statistical methods were used, including liner regression analysis, χ² test, and multivariate Cox proportional hazard model.

Results: Four hundred ninety-eight patients were included. Median follow-up was 5.26 years. High time weighted average of serum magnesium was associated with a hazard ratio of 1.94 for all-cause mortality and major cardiovascular outcome compared to low levels (95% CI 1.18–3.19, p = 0.009). The high quartile of time weighted average of serum magnesium was associated with death censored major cardiovascular outcome (hazard ratio 2.13, 95% CI 1.17–3.86, p = 0.013) in multivariate analysis.

Conclusions: Exposure to low serum magnesium levels in renal transplant recipients was associated with a lower risk for all-cause mortality and major cardiovascular outcome. These findings contrast the higher risk found in the general population.

Serum magnesium, hepatocyte nuclear factor 1β genotype and post-transplant diabetes mellitus: a prospective study

BACKGROUND

Retrospective studies suggest that tacrolimus-induced hypomagnesaemia is a risk factor for post-transplant diabetes mellitus (PTDM), but prospective studies are lacking.

METHODS

This was a prospective study with measurements of serum magnesium and tacrolimus at pre-specified time points in the first year after living donor kidney transplantation (KT). The role of single nucleotide polymorphisms (SNPs) in hepatocyte nuclear factor 1β (HNF1β) was also explored because HNF1β regulates insulin secretion and renal magnesium handling. Repeated measurement and regression analyses were used to analyse associations with PTDM.

RESULTS

In our cohort, 29 out of 167 kidney transplant recipients developed PTDM after 1 year (17%). Higher tacrolimus concentrations were significantly associated with lower serum magnesium and increased risk of hypomagnesaemia. Patients who developed PTDM had a significantly lower serum magnesium trajectory than patients who did not develop PTDM. In multivariate analysis, lower serum magnesium, age and body mass index were independent risk factors for PTDM. In recipients, the HNF1β SNP rs752010 G > A significantly increased the risk of PTDM [odds ratio (OR) = 2.56, 95% confidence interval (CI) 1.05-6.23] but not of hypomagnesaemia. This association lost significance after correction for age and sex (OR = 2.24, 95% CI 0.90-5.57). No association between HNF1β SNPs and PTDM was found in corresponding donors.

CONCLUSIONS

A lower serum magnesium in the first year after KT is an independent risk factor for PTDM. The HNF1β SNP rs752010 G > A may add to this risk through an effect on insulin secretion rather than hypomagnesaemia, but its role requires further confirmation.

Association Between Pre-Transplant Magnesemia and Post-Transplant Dysglycemia in Kidney Transplant Recipients

BACKGROUND

Serum magnesium (Mg) status in kidney transplant recipients has been a center of attention in the past few years. Current evidence suggests an association between pre-transplant hypomagnesemia and post-transplant hyperglycemia.

OBJECTIVE

The purpose of this study was to assess the associations of pre-transplant magnesemia with blood glucose disturbances within 6 months post-kidney transplantation.

METHODS

In this retrospective cohort, 89 first-time kidney transplant recipients with 6 months of follow-up were included. None of the participants had a positive history of rejection, pre-transplant history of diabetes mellitus or fasting plasma glucose ≥ 100 mg/dL.

RESULTS

Post-transplant diabetes mellitus (PTDM) and impaired fasting glucose (IFG) 6 months post-transplant was found in 7.9% and 41.6% of the study group, respectively. The mean pre-transplant serum Mg level was 1.92 ± 0.30 mg/dL in the study population (n = 89), and it was significantly lower in IFG (n = 37) and IFG/PTDM (n = 44) groups compared to normoglycemic (n = 45) recipients (1.83 ± 0.31 mg/dL vs. 2.00 ± 0.27 mg/dL, P = 0.008, and 1.84 ± 0.31 mg/dL vs. 2.00 ± 0.27 mg/dL, P = 0.012, respectively). Patients with serum Mg less than 1.9 mg/dL were nearly 2.6 times more likely to develop IFG or IFG/PTDM within 6 months post-transplant (P = 0.044 and P = 0.040, respectively).

CONCLUSIONS

Pre-transplant hypomagnesemia may be considered a risk factor for developing post-transplant glycemic disturbances, and patients with lower pre-transplant Mg concentration could be at a higher risk for developing IFG.

Pathogenesis and treatment of electrolyte problems post transplant

PURPOSE OF REVIEW

Electrolyte abnormalities posttransplant are common occurrences that can have significant short-term and long-term effects on graft outcome and patient quality of life. Understanding the pathophysiology of these electrolyte derangements can help guide management to optimize bone health and minimize cardiovascular disease. This review explores the pathogenesis of the most common postrenal transplant electrolytes abnormalities as well as current treatment options.

RECENT FINDINGS

Clarifications of the role of FGF-23 has improved our understanding of posttransplant bone disease in addition to the known roles of hyperparathyroidism and vitamin D. The mechanisms of renal electrolyte wasting by immunosuppressive agents give insight into potential treatment options for hyperkalemia and hypomagnesemia.

SUMMARY

Understanding the pathogenesis of the common electrolyte abnormalities found post renal transplant may lead to targeted treatment options that in turn may improve transplant complications. Further studies are required to evaluate the effects on long-term outcomes of renal allografts.

Prevention of complications from use of conventional immunosuppressants: a critical review

Synthetic immunosuppressive drugs are largely used in immune-related renal diseases and in kidney transplantation. Most of these drugs have a low therapeutic index (the ratio that compares the blood concentration at which a drug becomes toxic and the concentration at which the drug is effective), which means that the drug should be dosed carefully and the patient monitored frequently. In this review, we consider the categories of synthetic immunosuppressive agents more frequently and conventionally used in clinical nephrology: glucocorticoids, Aalkylating agents (cyclophosphamide, chlorambucil), purine synthesis inhibitors (azathioprine, mycophenolate salts) and calcineurin inhibitors (cyclosporine, tacrolimus). For each category the possible side effects will be reviewed, the general and specific measures to prevent or treat the adverse events will be suggested, and the more common mistakes that may increase the risk of toxicity will be described. However, the efficacy and safety of immunosuppressive agents depend not only on the pharmacologic characteristics of single drugs but can be influenced also by the clinical condition and genetic characteristics of the patient, by the typology and severity of the underlying disease and by the interaction with other concomitantly used drugs.

Electrolyte and Acid-Base Disorders in the Renal Transplant Recipient

Kidney transplantation is the current treatment of choice for patients with end-stage renal disease. Innovations in transplantation and immunosuppression regimens have greatly improved the renal allograft survival. Based on recently published data from the Scientific Registry of Transplant recipients, prevalence of kidney transplants is steadily rising in the United States. Over 210,000 kidney transplant recipients were alive with a functioning graft in mid-2016, which is nearly twice as many as in 2005. While successful renal transplantation corrects most of the electrolyte and mineral abnormalities seen in advanced renal failure, the abnormalities seen in the post-transplant period are surprisingly different from those seen in chronic kidney disease. Multiple factors contribute to the high prevalence of these abnormalities that include level of allograft function, use of immunosuppressive medications and metabolic changes in the post-transplant period. Electrolyte disturbances are common in patients after renal transplantation, and several studies have tried to determine the clinical significance of these disturbances. In this manuscript we review the key aspects of the most commonly found post-transplant electrolyte abnormalities. We focus on their epidemiology, pathophysiology, clinical manifestations, and available treatment approaches.

Serum Magnesium after Kidney Transplantation: A Systematic Review

Magnesium (Mg) status has recently drawn close attention in chronic kidney disease and in kidney transplant recipients. This review aims to evaluate the body of evidence linking hypomagnesemia to clinical consequences in these specific populations. After a brief summary of the main mechanisms involved in Mg regulation and of Mg status in end-stage renal disease, the review focuses on the relationship between hypomagnesemia and cardiovascular risk in kidney transplant recipients. A body of evidence in recent studies points to a negative impact of hypomagnesemia on post-transplant diabetes mellitus (PTDM) and cardiovascular risk, which currently represent the main threat for morbidity and mortality in kidney transplantation. Deleterious biological mechanisms induced by hypomagnesemia are also discussed. While data analysis enables us to conclude that hypomagnesemia is linked to the development of PTDM, studies prospectively evaluating the impact of hypomagnesemia correction after kidney transplantation are still lacking and needed.

Incidence of hyperglycemia and diabetes and association with electrolyte abnormalities in pediatric solid organ transplant recipients

Background

Posttransplant hyperglycemia is an important predictor of new-onset diabetes after transplantation, and both are associated with significant morbidity and mortality. Precise estimates of posttransplant hyperglycemia and diabetes in children are unknown. Low magnesium and potassium levels may also lead to diabetes after transplantation, with limited evidence in children.

Methods

We conducted a cohort study of 451 pediatric solid organ transplant recipients to determine the incidence of hyperglycemia and diabetes, and the association of cations with both endpoints. Hyperglycemia was defined as random blood glucose levels ≥11.1 mmol/L on two occasions after 14 days of transplant not requiring further treatment. Diabetes was defined using the American Diabetes Association Criteria. For magnesium and potassium, time-fixed, time-varying and rolling average Cox proportional hazards models were fitted to evaluate the association with hyperglycemia and diabetes.

Results

Among 451 children, 67 (14.8%) developed hyperglycemia and 27 (6%) progressed to diabetes at a median of 52 days (interquartile range 22-422) from transplant. Multi-organ recipients had a 9-fold [hazard ratio (HR) 8.9; 95% confidence interval (CI) 3.2-25.2] and lung recipients had a 4.5-fold (HR 4.5; 95% CI 1.8-11.1) higher risk for hyperglycemia and diabetes, respectively, compared with kidney transplant recipients. Both magnesium and potassium had modest or no association with the development of hyperglycemia and diabetes.

Conclusions

Hyperglycemia and diabetes occur in 15 and 6% children, respectively, and develop early posttransplant with lung or multi-organ transplant recipients at the highest risk. Hypomagnesemia and hypokalemia do not confer significantly greater risk for hyperglycemia or diabetes in children.

Longitudinal Study of the Role of Epidermal Growth Factor on the Fractional Excretion of Magnesium in Children: Effect of Calcineurin Inhibitors

BACKGROUND

It was shown in animal models and adults that the epidermal growth factor (EGF) is involved in the pathophysiology of calcineurin inhibitor (CNI) induced renal magnesium loss. In children, however, the exact mechanism remains unclear, which was set as the purpose of the present study.

METHODS

Children with nephrotic syndrome and renal transplant children treated with CNI (n = 50) and non-CNI treated children (n = 46) were included in this study. Urine and serum samples were collected at three time points to determine magnesium, creatinine, and EGF. The magnesium intake was calculated from a food frequency questionnaire.

RESULTS

Serum Mg²⁺ and urinary EGF/creatinine were significantly lower in the CNI treated children, with significantly more CNI-treated children developing hypomagnesaemia. In the latter patients, the fractional excretion of magnesium (FE Mg²⁺) was significantly higher. Urinary EGF, age, renal function, and serum magnesium were independent predictors of the FE Mg²⁺. Only 29% of the children reached the recommended daily intake of magnesium. The magnesium intake did not differ between hypomagnesemic and normomagnesemic patients and was not a predictor of the FE Mg²⁺.

CONCLUSIONS

In CNI-treated children who developed hypomagnesemia, the FE Mg²⁺ was increased. The urinary EGF concentration, age, and renal function are independent predictors of the FE Mg²⁺.

New-Onset Diabetes After Kidney Transplantation and Pretransplant Hypomagnesemia

AIM

Hypomagnesemia is a frequent finding in kidney transplant patients and plays a causal role in insulin resistance and diabetes. The aim of this study was to investigate whether the pretransplant magnesium (Mg) level is a risk factor for the development of new-onset diabetes after kidney transplantation (NODAT) and the presence of relationship between pretransplant hypomagnesemia and the development period of NODAT.

METHODS

Four hundred and nineteen nondiabetic renal transplant recipients were evaluated retrospectively. The patients were divided into NODAT and non-NODAT groups. The time of diagnosis of patients with NODAT was divided into 0 to 3, 3 to 6, 6 to 12 months, and after 12 months. Patients' characteristics and pretransplant Mg levels in NODAT were compared with non-NODAT, and it was investigated whether pretransplant hypomagnesemia was a risk factor for the development of NODAT.

RESULTS

Totally 70 (16.6%) patients (36 female [F], mean age 51.7 ± 8.2 years) were diagnosed with NODAT. Three hundred and forty-nine patients (115 F, mean age 43.2 ± 12.5 years) did not have NODAT. Pretransplant mean Mg level was 1.97 ± 0.40 mg/dL in patients with NODAT, while it was 2.5 ± 0.45 mg/dL in non-NODAT patients (P < .001). Serum Mg level was found to be similar in subgroups according to the development period of NODAT (P = .07). When patients were stratified according to quartiles of Mg level, the frequency of NODAT was significantly higher in patients in the lower quartile (Mg < 2.1 mg/dL; P < .001). Older age, high body mass index, and low pretransplant serum Mg levels were established as risk factors for developing NODAT. According to the quartile of Mg level, the risk of developing NODAT was highest in the lowest quartile.

CONCLUSION

Pretransplant hypomagnesemia is an independent risk factor of NODAT. Therefore, it is necessary to closely monitor the Mg levels in the posttransplant period.

Risk factors for new-onset diabetes mellitus after living donor kidney transplantation in Korea - a retrospective single center study

BACKGROUND

New-onset diabetes mellitus after transplantation (NODAT) is a serious complication following renal transplantation. The aim of this study was to identify the risk factors for the development of NODAT in Korean transplant patients.

METHODS

Recipients who underwent living donor kidney transplantation between January 2009 and April 2012 at Asan Medical Center were reviewed. Diagnosis of NODAT was defined according to the American Diabetes Association criteria.

RESULTS

A total of 418 patients were enrolled. NODAT was diagnosed in 85 (20.4 %) patients within 1 year. By multivariate analysis, old age (odds ratio [OR], 1.05; 95 % Confidence interval [CI]: 1.01-1.08), family history of diabetes mellitus (OR, 2.48; 95 % CI: 1.04-5.94), pre-transplant high serum glucose level (OR, 1.04; 95 % CI: 1.01-1.08), and obesity (OR, 3.46; 95 % CI: 1.55-7.73) were independent risk factors for NODAT.

CONCLUSION

Old age, family history of diabetes, pre-transplant high plasma glucose level, and obesity are independent factors associated with the development of diabetes after renal transplantation. In contrast, serum magnesium levels and the use of tacrolimus are not associated with the development of NODAT.

Hypomagnesemia and the Risk of New-Onset Diabetes Mellitus after Kidney Transplantation

Several studies suggest a link between post-transplant hypomagnesemia and new-onset diabetes after transplantation (NODAT), but this relationship remains controversial. We conducted a retrospective cohort study of 948 nondiabetic kidney transplant recipients from January 1, 2000, to December 31, 2011, to examine the association between serum magnesium level and NODAT. Multivariable Cox proportional hazards models were fitted to evaluate the risk of NODAT as a function of baseline (at 1 month), time-varying (every 3 months), and rolling-average (i.e., mean for 3 months moving at 3-month intervals) serum magnesium levels while adjusting for potential confounders. A total of 182 NODAT events were observed over 2951.2 person-years of follow-up. Multivariable models showed an inverse relationship between baseline serum magnesium level and NODAT (hazard ratio [HR], 1.24 per 0.1 mmol/L decrease; 95% confidence interval [95% CI], 1.05 to 1.46; P=0.01). The association with the risk of NODAT persisted in conventional time-varying (HR, 1.32; 95% CI, 1.14 to 1.52; P<0.001) and rolling-average models (HR, 1.34; 95% CI, 1.13 to 1.57; P=0.001). Hypomagnesemia (serum magnesium <0.74 mmol/L) also significantly associated with increased risk of NODAT in baseline (HR, 1.58; 95% CI, 1.07 to 2.34; P=0.02), time-varying (HR, 1.78; 95% CI, 1.29 to 2.45; P<0.001), and rolling-average models (HR, 1.83; 95% CI, 1.30 to 2.57; P=0.001). Our results suggest that lower post-transplant serum magnesium level is an independent risk factor for NODAT in kidney transplant recipients. Interventions targeting serum magnesium to reduce the risk of NODAT should be evaluated.

Hypomagnesaemia in kidney transplantation

In the era of calcineurin inhibitors, hypomagnesaemia is a very common finding in kidney transplant recipients. Especially the first weeks after transplantation it is the rule rather than the exception. Hypomagnesaemia or low magnesium intake have been associated with a higher mortality or more cardiovascular events in the general population, but this association has never been explored in kidney transplant recipients, despite their increased cardiovascular risk. Kidney transplant recipients with pre- or post-transplant hypomagnesaemia seem to have an aberrant glucose metabolism and develop diabetes mellitus more frequently. Moreover, observations from alternate study populations, animal experiments or in vitro studies suggest a possible role of magnesium deficiency in graft dysfunction, bone metabolism and transplant immunology. Future observational and especially interventional studies should further define whether and to what extent we should make effort to correct this electrolyte disturbance in transplant recipients. Considering the mechanism of renal magnesium wasting, normalizing the serum magnesium concentration by oral supplementation alone might turn out to be cumbersome in kidney transplant recipients.

Relation between pretransplant magnesemia and the risk of new onset diabetes after transplantation within the first year of kidney transplantation

BACKGROUND

New-onset diabetes after transplantation (NODAT) is a frequent condition associated with a poor outcome. In kidney transplantation, hypomagnesemia is a frequent posttransplant complication and has been associated with calcineurin inhibitors use. Previous studies have analyzed the relationship between posttransplant hypomagnesemia and the risk of NODAT and provided conflicting conclusions. We conducted an observational study to analyze the relationship between pretransplant magnesemia (Mg) and the risk of NODAT within the first year of kidney transplantation.

METHODS

A cohort study was conducted to determine the risk conferred by pretransplant magnesium level on development of NODAT within 1 year posttransplant. First time kidney transplant recipients between January 2005 and December 2010 with more than 6 months of follow-up were included. Mg was measured within the 24 hours preceding kidney transplantation. NODAT was defined according to the American Diabetes Association criteria.

RESULTS

Among the 154 patients analyzed, 28 (18.2%) developed NODAT at year 1. NODAT patients had lower levels of pretransplant Mg as compared with non-NODAT patients (P<0.02). When patients were divided into tertiles of Mg level, NODAT developed more frequently in patients in the lower tertile (Mg <2 mg/dL) as compared with patients in the higher tertile (Mg >2.3 mg/dL) (log rank, P<0.05). A multivariate analysis after adjustment to several variables demonstrated pretransplant Mg to be an independent risk factor of NODAT.

CONCLUSION

This study supports that a low pretransplant Mg level is an independent risk factor of NODAT in kidney transplant recipients.

Magnesium excretion and hypomagnesemia in pediatric renal transplant recipients

BACKGROUND

We investigated magnesium excretion and rate of hypomagnesemia in pediatric renal transplant recipients.

METHOD

The medical records of 114 pediatric renal transplant recipients were retrospectively evaluated. After exclusion of 23 patients, 91 patients were included in the study. We recorded serum magnesium levels at the time of measurement of urine magnesium wasting.

RESULTS

Mean serum magnesium levels were 1.73 ± 0.22 mg/dL and 38 of the patients (41%) had hypomagnesemia. There was a negative correlation between serum magnesium levels and estimated glomerular filtration rate and serum tacrolimus trough level (r=-0.215, p=0.040 and r=-0.409, p=0.000, respectively). Also, there was a statistically significant positive correlation between serum magnesium levels and transplantation duration (r=0.249, p=0.017). Mean fractional magnesium excretion was 5.9 ± 3.7% and 59 patients (65%) had high magnesium excretion. There was a significant negative correlation between fractional magnesium excretion and estimated glomerular filtration rate (r=-0.432, p=0.001). There was a significant positive correlation between fractional magnesium excretion and serum creatinine (r=0.379 p=0.003).

CONCLUSION

Patients with higher tacrolimus trough blood levels, lower glomerular filtration rate and at early posttransplant period had risk of hypomagnesemia.

Lower magnesium level associated with new-onset diabetes and pre-diabetes after kidney transplantation

BACKGROUND

Hypomagnesemia is associated with increased peripheral insulin resistance in the general population. It is frequently seen after renal transplantation. We examined its role as a risk factor for new-onset diabetes after transplantation (NODAT) and new-onset pre-diabetes after transplantation (NOPDAT).

METHODS

A retrospective analysis of 138 previously non-diabetic renal transplant recipients was conducted. Cox and logistic regression analyses were performed to examine the associations between 1-month post-transplant serum magnesium level and subsequent diagnoses of NODAT/NOPDAT.

RESULTS

NODAT was diagnosed in 34 (24.6 %) and NOPDAT in 12 (8.7 %) patients. Median time to diagnosis of NODAT/NOPDAT was 20.4 months (interquartile range [IQR] 6.8-34.8). Median follow up for the entire group was 3.5 years (IQR 2.3-5.6). Mean magnesium level at 1 month after transplantation was significantly lower in patients subsequently diagnosed with NODAT/NOPDAT (1.60 ± 0.27 vs. 1.76 ± 0.29 mg/dl, p = 0.002). Cox regression analysis identified a trend towards developing NODAT/NOPDAT with lower baseline magnesium levels (hazard ratio 0.89 per 0.1 mg/dl increment in magnesium level, 95 % confidence interval [CI] = 0.78-1.01, p = 0.07); a stronger relationship between the two variables was seen at logistic regression analysis (odds ratio 0.81 per 0.1 mg/dl increment in serum magnesium (95 % CI 0.67-0.98, p = 0.03).

CONCLUSIONS

A lower magnesium level at 1 month after transplantation may be predictive of a subsequent diagnosis of glucose intolerance or diabetes in renal transplant recipients. Whether replenishing magnesium stores can prevent development of these disorders requires further investigation.

New-onset diabetes after kidney transplantation: prevalence, risk factors, and management

New-Onset Diabetes After Transplantation (NODAT) is an increasingly recognized severe metabolic complication of kidney transplantation causing lower graft function and survival and reduced long-term patient survival mainly due to cardiovascular events. The real incidence of NODAT after kidney transplantation is difficult to establish, because different classification systems and definitions have been employed over the years. Several risk factors, already present before or arising after transplantation, in particular the employed immunosuppressive regimens, have been related to the development of NODAT. However the responsible pathogenic mechanisms are still far to be perfectly known. Awareness of NODAT and of the NODAT-related factors is of paramount importance for the clinicians in order to individuate higher risk patients and arrange screening strategies. The risk of NODAT can be reduced by planning preventive measures and by tailoring immunosuppressive regimens according to the patient characteristics. Once NODAT has been diagnosed, the administration of specific anti-hyperglycemic therapy is mandatory to reach a tight glycemic control, which contributes to significantly reduce posttransplant mortality and morbidity.