Urinary Calcium: A Marker of Bone Health in Youth With T1D?

TOPLINE:
Youths with type 1 diabetes (T1D) show lower bone accrual than expected for their age, gender, pubertal stage, lean mass accrual, and growth, with greater urinary calcium excretion being associated with impaired bone health.
METHODOLOGY:
A high level of urinary calcium excretion was once considered a feature of uncontrolled T1D and more recently has been cited as a potential contributor to the impaired bone health of children and adults with T1D, but contemporary data in individuals with intensive glycemic control are lacking.
Researchers conducted a two-part observational study to explore the association between urinary calcium excretion and bone accrual and the influence of glycemic control in youth aged 5-20 years with T1D (median T1D duration, 6 years [range, 1-18 years]).
A longitudinal study of 50 participants (median age, 15; 40% girls; mean A1c, 8.6) assessed bone accrual outcomes with two study visits (baseline and 12 months), and a cross-sectional study of 99 participants (median age, 15.2; 46.5% girls; mean A1c, 8.4) assessed the clinical determinants of 24-hour urinary calcium excretion, with 43 participants enrolled in both cohorts.
Whole body and regional dual-energy x-ray absorptiometry scans were performed to measure bone mineral content and density, and the bone mineral content was compared to a reference dataset of healthy children without T1D; urinary calcium excretion was assessed using 24-hour urine samples and spot urine samples.
The main outcomes were the whole body less head bone mineral content compared to the reference dataset (using an adjusted velocity Z-score specific to sex and pubertal stage) and fractional excretion of urinary calcium.
TAKEAWAY:
The longitudinal cohort had lower bone mineral accrual (Z-score, −0.3 ± 1.0; P = .03) compared to the reference dataset of healthy children without T1D.
Greater urinary calcium excretion was significantly associated with lower bone mineral accrual in the longitudinal cohort compared to the reference dataset (Z-score, −0.47; P = .001).
In the cross-sectional cohort, greater urinary calcium excretion was associated with lower intact parathyroid hormone, higher beta-C-telopeptide (a marker of bone resorption), and higher blood sugar (measured by A1c) and higher urine glucose concentration, according to multivariable regression models.
Both short-term (urine glucose) and long-term (A1c) markers of glycemic control were associated with greater urinary calcium excretion but neither was directly associated with bone accrual.
IN PRACTICE:
“Greater urinary calcium excretion was associated with diminished bone mineral accrual over 1 year in youth with T1D,” the authors wrote. “These findings suggest that studies of the effect of interventions to reduce urinary calcium excretion on bone outcomes should be considered in youth with T1D.”
SOURCE:
This study was led by David R. Weber, MD, MSCE, Department of Pediatrics, Children’s Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, and was published online in The Journal of Clinical Endocrinology & Metabolism.
LIMITATIONS: 
The study lacked a consensus on the optimal means of assessing urinary calcium excretion and the optimal timing of spot urine collection to assess calcium excretion, which may have affected the interpretation of the study findings. Urine collections were not done in duplicate. Experimental studies are needed to clarify the mechanisms.
DISCLOSURES:
One author reported receiving research grant funding from Inozyme Pharma and consulting fees from PTC Therapeutics.
This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.
 
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