Association Between Secondary Hyperparathyroidism and Body Composition in Pediatric Patients With Moderate and Advanced Chronic Kidney Disease

Abstract

Objective: This single center cross-sectional study aims to investigate the association between secondary hyperparathyroidism and body composition in pediatric patients with moderate (stage 3) and advanced (stage 4–5) chronic kidney disease (CKD).Methods: 61 patients (median age: 13.4 years) were included. Body composition indices, including lean tissue index (LTI) and fat tissue index (FTI), were measured using multi-frequency bio-impedance spectroscopy. Muscle wasting was defined as LTI adjusted to height-age (HA) z-score < −1.65 SD and high adiposity as FTI z-score > 1.65 SD. Serum mineral metabolism parameters, including serum intact parathormone (iPTH), calcium, phosphorus and 25-hydroxyvitamin D, as well as serum leptin were measured in each patient. In advanced CKD patients, the mean values of serum mineral laboratory parameters of the 6 months prior to body composition assessment were recorded, and alfacalcidol index, defined as weekly alfacalcidol dose (mcg/week) per pg/ml of iPTH × 1,000, was calculated.Results: In moderate CKD (31 patients), high iPTH (>90 ng/ml) was observed in 10 (32.3%) patients and was associated with higher FTI z-score (p = 0.022). Moreover, serum iPTH was negatively correlated to LTI HA z-score (rs = −0.486, p = 0.006), and positively correlated to serum leptin levels (rs = 0.369, p = 0.041). The positive correlation between FTI z-score and iPTH (rs = 0.393, p = 0.039) lost significance after adjustment for serum leptin. iPTH was positively associated with high adiposity (12 patients, 38.7%) after adjustment for the other mineral metabolism parameters (OR 1.023, 95% CI 1.002–1.045, p = 0.028). In advanced CKD (30 patients), no significant correlation was observed between iPTH and body composition indices and serum leptin levels. Eleven (36.7%) patients with muscle wasting presented lower alfacalcidol index (p = 0.017). Alfacalcidol index ≤ 24 was strongly associated with muscle wasting after adjustment for CKD stage and other mineral metabolism parameters (OR 7.226, 95% CI 1.150–45.384, p = 0.035).Conclusion: Secondary hyperparathyroidism is associated with high adiposity in moderate but not in advanced CKD, with leptin acting as a potential contributive factor. In advanced CKD, targeting higher alfacalcidol weekly dose per each unit of serum PTH seems beneficial for preventing muscle wasting.

High Prevalence of Hypovitaminosis D in Adolescents Attending a Reference Centre for the Treatment of Obesity in Switzerland

“…The relationship between vitamin D and PTH levels in obesity is complex. Some studies found that the PTH levels are positively associated with the BMI z-score [ 27 , 28 ]. A study conducted in adolescent girls with obesity showed that the ratio of PTH to vitamin D was negatively associated with measures of glucose homeostasis and positively associated with inflammatory markers [ 29 ].…”

Malnutrition Patterns in Children with Chronic Kidney Disease

“…Although a U-curve correlation was observed between BMI z-score and pulse wave velocity in a single center study, no association was observed between malnutrition status and carotid intima media thickness in another study on chronic dialysis children [ 28 , 31 ]. Furthermore, limited adult and pediatric studies suggest that overweight patients with moderate CKD may present secondary hyperparathyroidism earlier in the course of the disease, indicating a link between obesity and mineral bone disorders [ 32 , 33 , 34 ]. In the pediatric population, this condition may be more frequent in kidney transplant recipients, where obesity prevalence is higher, as observed in a recent study [ 35 ].…”

“…Data regarding the prevalence of fat mass loss in CKD pediatric patients are limited. Bioimpedance spectroscopy (BIS)-based body composition assessment revealed that low lean tissue index was observed in 22.6% of patients with moderate CKD and in 36.7% of patients with advanced CKD, while fat tissue index was observed in only 10% of patients with advanced CKD in a cross-sectional study on 61 patients [ 33 ]. Iyengar et al found body fat using Dual-energy X-ray absorptiometry (DXA) and bioimpedance analysis (BIA) was reduced in 18% and 12% of children with CKD 2-5D, respectively [ 73 ].…”