A proposal for standardizing urine collections for bone resorption markers measurement

Area of Science:

• Endocrinology and Metabolism
• Bone Biology and Osteoporosis Research

Background:

• Bone resorption markers exhibit diurnal variations, impacting the accuracy of bone dynamics assessment.
• Standardized urine collection is crucial for reliable measurement of bone resorption rates in postmenopausal women.

Purpose of the Study:

• To evaluate diurnal variations in bone resorption marker excretion.
• To identify optimal urine collection times for assessing bone resorption rate and bone dynamics in postmenopausal women.

Main Methods:

• Sixty postmenopausal women (ages 43-67) were divided into two groups based on femoral bone mineral density T-score.
• Urine samples were collected over three diurnal periods (7 am-3 pm, 3 pm-11 pm, 11 pm-7 am), as well as 24-hour collections and first morning voids.
• Bone formation markers (bone alkaline phosphatase, osteocalcin) and bone resorption markers (urinary hydroxyproline, pyridinoline, deoxypiridinoline, N-telopeptide, galactosyl hydroxylysine, CrossLaps) were measured.

Main Results:

• Nocturnal urine collections (11 pm-7 am) and first morning void samples yielded the most reliable data on bone resorption rates.
• These sample types may detect bone loss in osteopenic patients and women with low T-scores.
• Standardization of nocturnal or first morning void sample collection enhances accuracy and inter-study comparability.

Conclusions:

• Nocturnal and first morning void urine samples are recommended for standardized assessment of bone resorption markers.
• This approach improves the reliability of bone dynamics evaluation in postmenopausal women, including those with low bone density.
• Standardized collection facilitates more accurate comparisons across different research studies.