Janice Thompson

Accuracy of equations to predict basal metabolic rate in older women.

OBJECTIVEnTo assess the accuracy of several published equations for predicting basal metabolic rate (BMR) in older women.nnnDESIGNnBMR was assessed in 116 healthy, older white women, aged 60 to 82 years, on three successive mornings by indirect calorimetry. Body composition was determined by dual energy X-ray absorptiometry or hydrostatic weighing. The measured BMRs were compared with values obtained from eight published prediction equations that used solely, or in various combinations, measures of height, weight, fat-free mass, age, and menopausal status.nnnSTATISTICAL ANALYSES PERFORMEDnThe root mean squared prediction error (RMSPE) was used to determine how accurately predicted BMR matched actual BMR for each subject. In addition, regression analysis was used to evaluate accuracy of predicted BMR vs directly measured BMR.nnnRESULTSnPredicted mean BMR determined using all eight equations was significantly correlated to measured BMR (P = .0001), accounting for 30% to 52% of the variance of measured BMR. When analyzed by RMSPE, however, the equations of Owen et al (1986), Fredrix et al (1990), and Harris-Benedict (1919) predicted actual BMR for each subject within an average of 116 kcal/day, and the equation of Cunningham (1980) resulted in the largest prediction error at 208 kcal/day.nnnAPPLICATIONS/CONCLUSIONSnThe regression equations of Owen et al (1986), which used body weight, Fredrix et al (1990), which used body weight and age, and Harris-Benedict (1919), which used age, weight, and height as variables, were most accurate in predicting BMR in our sample of healthy older women.

Functional consequences of the somatopause and its treatment

The decline in the function of the growth hormone-releasing hormone, growth hormone, insulin-like growth factor (GHRH-GH-IGF) axis has been termed the somatopause. Many of the catabolic sequelae seen in normal aging has been attributed to this decrease in circulating GH and IGF-I. In order to provide hormone replacement therapy for the somatopause, elderly subjects have been treated with GH, IGF-I, or both hormones together. Whereas numerous beneficial effects on body composition, strength, and quality of life have been reported in some studies, other studies have reported only marginal functional imporvements. Moreover, it is clear that both hormones can cause significant morbidity.

Effects of Recombinant Human Insulin-Like Growth Factor I in Aging

While growth hormone (GH) is necessary for metabolic homeostasis in infants and for linear growth in children, the role of this pituitary hormone in adults has not yet been clarified. It has long been appreciated that normal aging is associated with a decline in the activity of the GH releasing hormone (GHRH)-GH-insulin-like growth factor I (IGF-I) axis, and it has recently been suggested that many of the degenerative changes seen in the elderly, such as muscle wasting and osteopenia, are in part caused by relative GH and/or IGF-I deficiency. It has been postulated that the age-related decline in the activity of the hypothalamic-somatotroph-IGF-I axis results in a catabolic diathesis that leads to falls, fractures, and frailty in the elderly, a syndrome complex that has been named the somatopause (1).