Adynamic bone disease may be the most common manifestation of chronic kidney disease mineral bone disorder (CKD-MBD) in pre-dialysis patients with type 2 diabetes, new research shows.

Sayantan Ray, MBBS, MD, of the Institute of Post Graduate Medical Education & Research and SSKM Hospital in India, and colleagues investigated the profile of CKD-MBD in 72 patients with type 2 diabetes with newly-diagnosed stage 4–5 CKD not on dialysis (mean age 54.2; 39% female). None of the patients had received treatment with calcium supplements, phosphate binders, vitamin D analogues, glucocorticoids, anticonvulsants, non-steroidal anti-inflammatory drugs, or bisphosphonates. The investigators defined adynamic bone disease as intact pararthyroid hormone (iPTH) levels below 70 pg/mL in stage 4 CKD and below 100 pg/mL in stage 5 CKD.

The study revealed hyperparathyroidism in 43% of patients with stage 4 CKD (iPTH above 110 pg/mL) and 32% of patients with stage 5 CKD (iPTH above 300 pg/mL), suggesting that high bone turnover disease was not predominant in this population.

“Nearly 40% of patients in each group (CKD stage 4 and 5) showed biochemical parameters consistent with low turnover bone disease, highlighting that adynamic bone disease is prevalent even in [the] pre-dialysis CKD population,” Dr Ray and his team concluded in a paper published online ahead of print in Diabetes & Metabolic Syndrome: Clinical Research & Reviews. They also noted that the relatively low prevalence of hyperparathyroidism in their cohort “could mean that high bone turnover disease may not be the most prevalent type in diabetic CKD.”

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Laboratory results showed that roughly a third of patients had hypocalcemia (38.5%) and hyperphosphatemia (31.43%). Patients with stage 5 CKD had lower corrected serum calcium and significantly higher inorganic phosphorus, total alkaline phosphatase (ALP), and iPTH. Overall, 24.2% of patients had vitamin D deficiency (less than 10 ng/mL) and 41.4% had vitamin D insufficiency (10–20 ng/mL). Higher ALP correlated with lower 25-hydroxyvitamin D.

In addition, the investigators found that patients with osteoporosis had higher iPTH levels than those with osteopenia or normal bone density (220.1 vs 119 pg/mL). In an adjusted multivariable regression model, iPTH predicted bone mineral density. These findings suggest “a contribution of high turnover in the genesis of osteoporosis,” even while it may not occur as frequently.

Higher urine albumin-to-creatinine ratio correlated with 25-hydroxyvitamin D levels, suggesting that proteinuria in type 2 diabetes patients may be linked with low vitamin D, the study found.

According to the investigators, iPTH and total ALP showed a clear, continuous linear relationship, supporting ALP’s utility as a marker of bone turnover. The researchers acknowledged that iPTH levels alone may not discriminate adynamic bone disease, which is a study limitation.

Reference

Raya S, Beatrice AM, Ghosh A, et al. Profile of chronic kidney disease related-mineral bone disorders in newly diagnosed advanced predialysis diabetic kidney disease patients: A hospital-based cross-sectional study. Diab Met Syndr: Clin Res Rev. doi: 10.1016/j.dsx.2017.07.019 [Epub ahead of print]