Mineral metabolism disrupted in CKD patients with diabetes
MedWire News: Disordered mineral metabolism is more severe and develops earlier in the course of chronic kidney disease (CKD) in patients with diabetes than it does in those without diabetes, report US researchers.
"These findings extend the previously reported differences in mineral metabolism found in small studies of predialysis CKD, and emphasize the potential need for greater surveillance of mineral metabolism in diabetic patients with early CKD," they say.
Led by Tamara Isakova (University of Miami Miller School of Medicine, Florida), the team measured mineral metabolites in baseline samples from 3756 participants from the Chronic Renal Insufficiency Cohort Study. All individuals had mild-to-moderate CKD, defined as an estimated glomerular filtration rate (eGFR) of 20-70 mL/min per 1.73 m2.
The team hypothesized that individuals with diabetes would have more severe abnormalities of mineral metabolism at comparable levels of renal dysfunction than patients without diabetes.
As reported in Diabetes Care, 48% of the participants had diabetes. Compared with nondiabetic individuals, those with the condition had a significantly lower mean eGFR, at 40.7 versus 44.7 versus mL/min per 1.73 m2 and a significantly higher mean urinary protein excretion rate, at 0.38 versus 0.311 g/day.
Mean levels of three mineral metabolism markers - serum phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23) - were significantly higher in diabetic compared with nondiabetic individuals, at 3.9 versus 3.5 mg/dL, 60.3 versus 49.5 pg/mL, and 172.4 versus 121.9 RU/mL, respectively, while the mean serum calcium level was significantly lower, at 9.1 versus 9.2 mg/dL.
The team also found that the eGFR cutpoint at which 50% of the participants met criteria for secondary hyperparathyroidism (PTH ≥65 pg/mL) was significantly higher in patients with diabetes than it was in those without the condition, at 30-39 versus 20-29 mL/min per 1.73 m2. Likewise, the cutpoint at which half of the participants had an excess FGF23 level (≥100 RU/mL) was significantly higher in those with diabetes compared to those without, at 50-59 versus 40-49 mL/min per 1.73 m2.
In addition, hyperphosphatemia was significantly more prevalent among those with diabetes in every 10-point range of eGFR than it was in those without diabetes.
"Although long term trials targeting mineral metabolism in diabetic patients with CKD are needed, in the interim our data support closer surveillance of mineral metabolism markers in this population," conclude the authors.
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By Sally Robertson