Use of Recombinant Human Parathyroid Hormone to Treat Hungry Bone Syndrome in Hemodialysis Patient

We report the case of a 35-year-old female with end-stage renal disease on hemodialysis for nine years. She was diagnosed with secondary hyperparathyroidism complicated with a brown tumor in the mandible. After medical therapy failed, she underwent total parathyroidectomy (PTX), which was complicated by severe and prolonged hypocalcemia (hungry bone syndrome). Post-surgery, she required prolonged and frequent intravenous calcium and a high dose of vitamin D resulting in frequent admission with symptomatic hypocalcemia. Her serum magnesium was noted to be in the normal range. She continued to be hypocalcemic for nearly eight months post-surgery despite the intensive treatment. Recombinant human parathyroid hormone (teriparatide) 20 mg daily resulted in normalization of calcium within two weeks. The use of parathyroid hormone proved to be an effective treatment approach in this case. Proper pre-operative preparation and subtotal PTX with an adequate dose of vitamin D and calcium supplement may have been a rational option for this case.

[Long-term efficacy of parathyroidectomy in secondary and tertiary hyperparathyroidism]

BACKGROUND

Secondary and tertiary hyperparathyroidism (SHPT and THPT), are complications of chronic kidney disease (CKD), characterized by high levels of serum parathormone, hyperphosphatemia or hypercalcemia, respectively. If diet and pharmacological therapies fail, clinical practice guidelines suggest parathyroidectomy (PTX). Some studies have described its effectiveness and safety, but these have not included Mexican population.

OBJECTIVE

To describe long-term effectiveness of PTX in Mexican patients with SHPT or THPT.

MATERIAL AND METHODS

Observational and retrospective study of patients treated with PTX between 1995 and 2014 in a third level hospital in Mexico City. The analyses included the follow-up of medical treatment and biochemical assessment every three months during the first year, and the last evaluation. Permutation and chi square tests were used.

RESULTS

The study included 27 patients (14 women). The follow-up mean was 39 months; 61.5% had SHPT. All biochemical parameters, except magnesium, were reduced in the first year of follow-up. In the long term, SHPT was controlled in 80% using PTH under a 300 pg/mL criterion, and 90% in patients with THPT using calcium criterion. Persistent hypocalcemia was present in 11.5% of cases.

CONCLUSION

Mexican patients with SHPT and THPT could be successfully treated with surgery with low risk of hypocalcemia.

Trimethylamine N-Oxide and Cardiovascular Outcomes in Patients with ESKD Receiving Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Trimethylamine N-oxide (TMAO), a compound derived from byproducts of intestinal bacteria, has been shown to accelerate atherosclerosis in rodents. To date, there are conflicting data regarding the association of serum TMAO with cardiovascular outcomes in patients with ESKD, a population exhibiting both high serum TMAO and excessive atherosclerosis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured baseline serum TMAO concentrations in a subset of participants (n=1243) from the Evaluation of Cinacalcet Hydrochloride Therapy to Lower Cardiovascular Events (EVOLVE) trial and conducted post hoc analyses evaluating the association between baseline serum TMAO and cardiovascular outcomes.

RESULTS

We observed a wide distribution of serum TMAO in our cohort, with approximately 80% of participants exhibiting TMAO concentrations ≥56 µM and a maximum TMAO concentration of 1103.1 µM. We found no association between TMAO and our primary outcome, a composite of cardiovascular mortality, myocardial infarction, peripheral vascular event, stroke, and hospitalization for unstable angina. Moreover, in unadjusted and adjusted analyses, we observed no relation between TMAO and all-cause mortality, the independent components of our composite outcome, or the original EVOLVE primary outcome. Although we did observe higher TMAO concentrations in white participants, further subgroup analyses did not confirm the previously identified interaction between TMAO and race observed in a prior study in patients receiving dialysis.

CONCLUSIONS

We found no evidence linking TMAO to adverse clinical outcomes in patients receiving maintenance hemodialysis with moderate to severe secondary hyperparathyroidism.

Variability in Cinacalcet Prescription across US Hemodialysis Facilities

BACKGROUND AND OBJECTIVES

Calcimimetic drugs used to treat secondary hyperparathyroidism are being considered for inclusion in the Medicare ESRD Prospective Payment System bundle after an evaluation period. Understanding of utilization patterns of calcimimetics across dialysis facilities may help align financial incentives with clinical objectives. Our study's purpose was to describe the distribution of cinacalcet prescription across United States hemodialysis facilities and to explore factors that may influence cinacalcet utilization.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used monthly cross-sectional data from the Dialysis Outcomes and Practice Patterns Study in 2014 to characterize the distribution of cinacalcet prescription across 203 United States hemodialysis facilities (10,521 patients). On the basis of associations with parathyroid hormone levels from patient-level analyses, we used linear mixed-effects regressions to estimate the associations between three facility-level exposures (black race, <65 years old, and having ≥3 years on dialysis [vintage]) and the prevalence of cinacalcet prescription, adjusting for facility- and patient-level potential confounders.

RESULTS

The mean percentage of patients in each facility with cinacalcet prescription was 23% in June 2014 (median, 22%; interquartile range, 13%-30%). Adjusted for facility-level and nonexposure patient-level variables, the difference in prevalence of cinacalcet prescription between facilities with the highest and lowest quartiles of percentage of black patients was 7.8% (95% confidence interval [95% CI], 0.8% to 14.8%; P for trend =0.03). The adjusted prevalence difference was 7.3% for the percentage of patients aged <65 years (95% CI, -0.1% to 14.7%; P for trend =0.06) and 11.9% for the percentage of patients with ≥3 years of dialysis (95% CI, 2.4% to 21.4%; P for trend =0.02). These associations changed appreciably, becoming much weaker or even reversing, after further adjusting for the patient-level exposure variables.

CONCLUSIONS

Facilities treating more patients who are black, under age 65 years, and having dialysis vintage ≥3 years have higher average levels of cinacalcet prescription. However, these differences were strongly attenuated after accounting for the unbalanced distributions of these patient case-mix variables.

The effect of vitamin C on parathyroid hormone in patients on hemodialysis with secondary hyperparathyroidism: a double blind, placebo-controlled study

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a prevalent disorder in patients with chronic kidney disease. It is proffered that there is a contradictory relation between serum level of vitamin C and parathyroid hormone (PTH) in hemodialysis patients with secondary hyperparathyroidism.

OBJECTIVES

The goal of this study was to assess the effects of the supplemental vitamin C on parathyroid hormone among hemodialysis patients with secondary hyperparathyroidism.

PATIENTS AND METHODS

This randomized, placebo-controlled, double-blind and parallel-group trial was conducted on 82 hemodialysis patients with serum levels of PTH more than 200 pg/mL. In intervention group, 250 mg vitamin C was injected three times a week for 8 weeks in a row immediately at the end of each dialysis session via the intravenous route. In the control group, same term of placebo saline was injected.

RESULTS

The mean of serum PTH was 699.81 (± 318.8) and 596.03 (± 410.7) pg/mL in intervention and control groups respectively at baseline (reference range, 6 to 66 pg/mL), and at the end of study it changed to 441.4 and 424.6 in these groups. The values of serum Calcium and Phosphate did not significantly change during the study (8.4 ± 0.6 mg/dL versus 8.1 ± 0.8 mg/dL, P = 0.39; 5.89 ± 1.7 mg/dL versus 5.9 ± 1.9 mg/dL, P = 0.08, respectively).

CONCLUSIONS

This study finding does not warranted therapeutic effect of vitamin C on secondary hyperparathyroidism.