Masters Theses

Date of Award

6-1973

Degree Type

Thesis

Degree Name

Master of Science

Major

Nutrition

Major Professor

Roy E. Beauchene

Committee Members

Rossie L. Mason, Jane R. Savage, Bernadine Meyer

Abstract

Relationships among bone density, urinary hydroxyproline (HOP), and the metabolic balances of calcium, phosphorus, and nitrogen were investigated in 16 elderly women.

The subjects resided at Eastern State Psychiatric Hospital, Knoxville, Tennessee. They ranged in age from 68 to 82 years with a mean age of 74. The consent of each subject and that of her nearest relative or guardian and of the medical staff of the hospital was obtained before participation in the study was permitted.

Twenty-four-hour urine and fecal samples and food samples, including snacks, were collected over a 7-day period. Weighed food consumptions of each subject were obtained during the same period. Food, urine, and fecal samples were analyzed for calcium, phosphorus, and nitrogen content and urine was also analyzed for HOP and creatinine per 24 hours. In addition, HOP excretion was standardized for creatinine excretion and body surface area. The height, weight, and bone density of each subject was determined and body surface area (m2) was calculated from a nomogram using the height and weight measurements.

The mean intakes for nitrogen, phosphorus, and calcium were 9.00 g, 1038 mg, and 770 mg, respectively. All 16 subjects were in positive nitrogen and phosphorus balance, while 12 out of 16 women were in negative calcium balance with mean balances of 2.29 g, 258 mg, and -52.4 mg, respectively. Urinary nitrogen and phosphorus excretions were significantly correlated with nitrogen (r = 0.92, P < .001) and phosphorus (r = 0.61, P < .006) intakes, respectively. Nitrogen, calcium, and phosphorus intakes were positively correlated with nitrogen (r = 0.74, P < .001), calcium (r = 0.58, P < .01), and phosphorus (r = -0.31, P = .099) intakes to decrease with age, while decrements in phosphorus intakes were significant with age (r = -0.42, P < .05).

The mean values for HOP excretion (24 mg) and for HOP excretion per square meter of body surface area (16 mg/24 hr/m2) were normal, while the mean value for the HOP-creatinine ratio (41 mg/g) was high in comparison to values reported in the literature. Hydroxyproline excretion and HOP excretion per m2 were both positively correlated with the urinary excretions of creatinine, nitrogen, calcium, and phosphorus (P < .05). In addition, HOP excretion (r = O. 78, P < .001) and HOP excretion per m2 (r = -0.43, P < .05) were both negatively correlated with age.

The mean bone density was 0.80 gram equivalents of alloy per cubic centimeter of bone, which was normal in comparison to values reported in the literature. The mean creatinine excretion was 0.607 g, which was low in comparison to values cited in the literature. Bone density was correlated with body weight (r = 0.51, P < .02), HOP excretion (r = 0.45, P < .04), and creatinine excretion (r = 0.43, P < .05), while the latter was correlated with body weight (r = 0.70, P < .001). No significant relationships were found between either bone density or creatinine excretion with age.

It was concluded that the quantity of osseous tissue was reflected in body weight and in HOP excretion. Also, from the relationships obtained among HOP excretion, bone density, body weight, and age, it was concluded that an age-associated decrement in body collagen turnover occurred.

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