Serum Markers of Low-Turnover Bone Disease in Mexican Children with Chronic Kidney Disease Undergoing Dialysis

Abstract

Background The frequency of low-turnover bone disease (LTBD) in patients with chronic kidney disease (CKD) has increased in past years. This change is important because LTBD is associated with bone pain, growth delay, and higher risk for bone fractures and extraosseous calcifications. LTBD is a histological diagnosis. However, serum markers such as parathyroid hormone (PTH) and calcium levels offer a noninvasive alternative for diagnosing these patients. Objective To describe the prevalence of LTBD in pediatric patients with renal failure undergoing some form of renal replacement therapy, using serum calcium and intact PTH levels as serum markers. Methods In this cross-sectional study, 41 children with CKD undergoing dialysis treatment (31 on continuous ambulatory peritoneal dialysis and 10 on hemodialysis) were included. There were no inclusion restrictions with respect to gender, cause of CKD, or dialysis modality. The children were studied as outpatients. The demographic data, CKD course, time on dialysis, phosphate-binding agents, and calcitriol prescription were registered, as well as weight, height, Z-score for height, linear growth rate, and Z-score for body mass index. Serum calcium, phosphorus, aluminum, PTH, alkaline phosphatase, osteocalcin, glucose, creatinine, urea, cholesterol, and triglycerides were measured. Results There were 20 (48.8%) children with both PTH <150 pg/mL and corrected total calcium >10 mg/dL who were classified as having LTBD[(+)]; the remaining 21 (51.2%) children were classified as having no LTBD[(–)]. The LTBD(+) patients were younger (11.2 ± 2.7 vs 13.2 ± 2.4 years, p < 0.01) but they had no differences regarding Z-scores for height. Linear growth in 6 months was less than expected in both groups (-0.15 ± 0.23 cm/month), but the difference between expected and observed growth was higher in the LTBD(+) group (-0.24 ± 0.14 vs –0.07 ± 0.28 cm/mo, p < 0.03). LTBD(+) patients also had lower serum creatinine (8.69± 2.75 vs 11.19 ± 3.17 mg/dL, p < 0.01), higher serum aluminum levels [median (range) 38.4 (9 – 106) vs 28.1 (9 – 62) μg/L, p < 0.05], and lower systolic blood pressure (112.0 ± 10.3 vs 125.0 ±12.9 mmHg, p < 0.015) and diastolic blood pressure (76.0 ± 9.7 vs 84.5 ± 8.2 mmHg, p < 0.017). A significant correlation was found between PTH and alkaline phosphatase ( r = 0.68, p < 0.001), but not between PTH and aluminum. Conclusion The LTBD(+) biochemical profile was found in 48.8% of the children and was associated with impaired linear growth. Aluminum contamination, evidenced by higher serum aluminum levels, may have had a pathogenic role in these disorders. Higher systolic and diastolic blood pressure levels may be related to higher serum PTH levels.

Chronic Kidney Disease and Dialysis in Mexico

“…In a small case series of Mexican children on dialysis, a surprisingly high rate of patients with low-turnover bone disease was found. Since in these children the prevalence of diabetes is low, the cause may be related to the high calcium content of the dialysis solutions, the use of calcium carbonate as phosphate-chelating agent, and aluminum toxicity (23,24).…”

Growth of prepubertal children on dialysis

“…In adult dialysis patients, total alkaline phosphatase, as well as bone alkaline phosphates, predicted normal bone formation rate and adynamic bone disease taken as a group together versus high-turnover bone disease, with a sensitivity of 76% and specificity of 60% [77]. Bayazit and co-workers [79], as well as the group of Avila-Diaz [80], reported a correlation of PTH and alkaline phosphatase in children on dialysis. In the latter group, patients with PTH of less than 150 pg/ml were classified as low bone turnover patients.…”

Adynamic Bone Revisited: Is there Progress?

“…In addition, diminutive amounts of aluminum can still be found in drugs used to treat gastric hyperacidity, in total parenteral nutrition, and water contamination during hemodialysis. As reported in the study by Ávila–Díaz and colleagues in this issue of Peritoneal Dialysis International , the presence of aluminum should still be investigated if low-turnover bone is present, especially in hemodialysis patients, who may develop the skeletal lesion by exposure to contaminated water source (20).…”