Urinary calcium, sodium, and bone mass of young females

• Published in: The American journal of clinical nutrition Vol. 62; no. 2; pp. 417 - 425
• Main Authors: Matkovic, V, Ilich, JZ, Andon, MB, Hsieh, LC, Tzagournis, MA, Lagger, BJ, Goel, PK
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.08.1995; American Society for Clinical Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: Absorptiometry, Photon; Adolescent; Aging - physiology; Aging - urine; Anthropometry; Biological and medical sciences; Bone Density - physiology; Bones; Calcium; Calcium - analysis; Calcium - metabolism; Calcium - urine; Calcium, Dietary - administration & dosage; Child; Creatinine - urine; Cross-Sectional Studies; Diet; Diet - standards; Female; Fundamental and applied biological sciences. Psychology; Girls; Humans; Metabolisms and neurohumoral controls; Nutrition Assessment; Physical growth; Puberty - metabolism; Puberty - physiology; Regression Analysis; Sodium - administration & dosage; Sodium - metabolism; Sodium - urine; Sodium, Dietary - administration & dosage; Teenagers; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Water and mineral metabolism. Osmoregulation. Acidobasic balance; Human; Excretion; Nutrition; Calcium; Interaction; Ions; Metabolism; Inorganic element; Feeding; Osteoarticular system; Bone mass; Sodium; Adolescent; Female; Nutrient; Skeleton; Bone; Somatic growth
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/62.2.417

Calcium is an important determinant of peak bone mass in young adults because of its influence on skeletal development during growth. Attainment of maximum peak bone mass requires optimal positive balance between calcium intake and obligatory losses of calcium, primarily in urine and feces. Urinary excretion is an important determinant of calcium retention in the body. Accordingly, the purpose of this study was to evaluate the influence of various nutrients on urinary calcium excretion, and to assess their impact on bone mass of young females, aged 8-13 y, during early puberty. The study was conducted in 381 healthy white females in pubertal stage 2. From each participant we collected basic anthropometric measurements, a 3-d food record, blood, a 24-h urine sample, and bone mass measurements of the total body and forearm by dual X-ray absorptiometry. Urinary sodium was found to be one of the most important determinants of urinary calcium excretion: [urinary calcium (mmol/d) = 0.01154 x urinary sodium (mmol/d) + 0.823], whereas calcium intake had relatively little impact: [urinary calcium (mmol/d) = 0.02252 x calcium intake (mmol/d) + 1.5261]. Urinary calcium was much higher at a calcium intake of approximately 37.5 mmol/d (1500 mg/d), supporting the notion that calcium is a threshold nutrient. Calcium intake had a significant positive influence on the bone mineral content and density of the whole body and radius shaft whereas urinary calcium had a negative influence, presumably by reducing calcium accretion into the skeleton.