What parathyroid hormone levels should we aim for in children with stage 5 chronic kidney disease; what is the evidence?

The bone disease that occurs as a result of chronic kidney disease (CKD) is not only debilitating but also linked to poor growth and cardiovascular disease. It is suspected that abnormal bone turnover is the main culprit for these poor outcomes. Plasma parathyroid hormone (PTH) levels are used as a surrogate marker of bone turnover, and there is a small number of studies in children that have attempted to identify the range of PTH levels that correlates with normal bone histology. It is clear that high PTH levels are associated with high bone turnover, although the range is wide. However, the ability of PTH levels to distinguish between low and normal bone turnover is less clear. This is an important issue, because current guidelines for calcium and phosphate management are based upon there being an “optimum” range for PTH. This editorial takes a critical look at the evidence upon which these recommendations are based

1,25(OH)2D3 Alters Growth Plate Maturation and Bone Architecture in Young Rats with Normal Renal Function

Whereas detrimental effects of vitamin D deficiency are known over century, the effects of vitamin D receptor activation by 1,25(OH)2D3, the principal hormonal form of vitamin D, on the growing bone and its growth plate are less clear. Currently, 1,25(OH)2D3 is used in pediatric patients with chronic kidney disease and mineral and bone disorder (CKD-MBD) and is strongly associated with growth retardation. Here, we investigate the effect of 1,25(OH)2D3 treatment on bone development in normal young rats, unrelated to renal insufficiency. Young rats received daily i.p. injections of 1 µg/kg 1,25(OH)2D3 for one week, or intermittent 3 µg/kg 1,25(OH)2D3 for one month. Histological analysis revealed narrower tibial growth plates, predominantly in the hypertrophic zone of 1,25(OH)2D3-treated animals in both experimental protocols. This phenotype was supported by narrower distribution of aggrecan, collagens II and X mRNA, shown by in situ hybridization. Concomitant with altered chondrocyte maturation, 1,25(OH)2D3 increased chondrocyte proliferation and apoptosis in terminal hypertrophic cells. In vitro treatment of the chondrocytic cell line ATDC5 with 1,25(OH)2D3 lowered differentiation and increased proliferation dose and time-dependently. Micro-CT analysis of femurs from 1-week 1,25(OH)2D3-treated group revealed reduced cortical thickness, elevated cortical porosity, and higher trabecular number and thickness. 1-month administration resulted in a similar cortical phenotype but without effect on trabecular bone. Evaluation of fluorochrome binding with confocal microscopy revealed inhibiting effects of 1,25(OH)2D3 on intracortical bone formation. This study shows negative effects of 1,25(OH)2D3 on growth plate and bone which may contribute to the exacerbation of MBD in the CKD pediatric patients

Efficacy and safety of paricalcitol in children with stages 3 to 5 chronic kidney disease

BACKGROUND: Elevated intact parathyroid hormone (iPTH) levels can contribute to morbidity and mortality in children with chronic kidney disease (CKD). We evaluated the pharmacokinetics, efficacy, and safety of oral paricalcitol in reducing iPTH levels in children with stages 3-5 CKD.METHODS: Children aged 10-16 years with stages 3-5 CKD were enrolled in two phase 3 studies. The stage 3/4 CKD study characterized paricalcitol pharmacokinetics and compared the efficacy and safety of paricalcitol with placebo followed by an open-label period. The stage 5 CKD study evaluated the efficacy and safety of paricalcitol (no comparator) in children with stage 5 CKD undergoing dialysis.RESULTS: In the stage 3/4 CKD study, mean peak plasma concentration and area under the time curve from zero to infinity were 0.13 ng/mL and 2.87 ng•h/((or ng×h/))mL, respectively, for 12 children who received 3 μg paricalcitol. Thirty-six children were randomized to paricalcitol or placebo; 27.8% of the paricalcitol group achieved two consecutive iPTH reductions of ≥30% from baseline versus none of the placebo group (P = 0.045). Adverse events were higher in children who received placebo than in those administered paricalcitol during the double-blind treatment (88.9 vs. 38.9%; P = 0.005). In the stage 5 CKD study, eight children (61.5%) had two consecutive iPTH reductions of ≥30% from baseline, and five (38.5%) had two consecutive iPTH values of between 150 and 300 pg/mL. Clinically meaningful hypercalcemia occurred in 21% of children.CONCLUSIONS: Oral paricalcitol in children aged 10-16 years with stages 3-5 CKD reduced iPTH levels and the treatment was well tolerated. Results support an initiating dose of 1 μg paricalcitol 3 times weekly in children aged 10-16 years.</p

Nutrition in children with CRF and on dialysis

The objectives of this study are: (1) to understand the importance of nutrition in normal growth; (2) to review the methods of assessing nutritional status; (3) to review the dietary requirements of normal children throughout childhood, including protein, energy, vitamins and minerals; (4) to review recommendations for the nutritional requirements of children with chronic renal failure (CRF) and on dialysis; (5) to review reports of spontaneous nutritional intake in children with CRF and on dialysis; (6) to review the epidemiology of nutritional disturbances in renal disease, including height, weight and body composition; (7) to review the pathological mechanisms underlying poor appetite, abnormal metabolic rate and endocrine disturbances in renal disease; (8) to review the evidence for the benefit of dietetic input, dietary supplementation, nasogastric and gastrostomy feeds and intradialytic nutrition; (9) to review the effect of dialysis adequacy on nutrition; (10) to review the effect of nutrition on outcome