Urinary calcium and renal function in the Japanese female population

Area of Science:

• Nephrology
• Nutritional Science
• Endocrinology

Background:

• Japanese population exhibits inadequate calcium (Ca) intake, falling below the recommended daily allowance (RDA) of 600 mg/day.
• Calcium deficiency is a significant public health concern, potentially impacting bone health and overall well-being.

Purpose of the Study:

• To investigate factors influencing urinary calcium (U-Ca) levels in calcium-deficient Japanese females.
• To explore the relationship between renal function markers and urinary calcium excretion in this demographic.

Main Methods:

• Cross-sectional study involving 210 Japanese females aged 24-76 years.
• Survey of dietary calcium intake, age, body mass index (BMI), and lifestyle factors (drinking, smoking).
• Analysis of urinary calcium (U-Ca), urinary albumin (U-Alb), and urinary retinol binding protein (U-RBP) as indicators of renal function.

Main Results:

• Mean calcium intake was 542.8 mg/day, confirming calcium deficiency among participants.
• A significant positive correlation was observed between urinary retinol binding protein (U-RBP) and urinary calcium (U-Ca).
• No significant associations were found between U-Ca and age, BMI, drinking habits, smoking habits, calcium intake, or urinary albumin (U-Alb).

Conclusions:

• In calcium-deficient Japanese females, proximal tubular dysfunction, indicated by elevated U-RBP, may be a key factor contributing to increased urinary calcium loss.
• This elevated urinary calcium loss could represent a potential risk factor for osteoporosis in this population.
• Further research is warranted to elucidate the mechanisms linking tubular dysfunction and calcium excretion in the context of dietary calcium inadequacy.