Aging, Total Body Potassium, Fat-free Mass, and Cell Mass in Males and Females Between Ages 18 and 85 Years

1972 ◽  
Vol 27 (4) ◽  
pp. 438-443 ◽  
Author(s):  
L. P. Novak
Keyword(s):  
Cell Mass ◽  
Fat Free Mass ◽  
Total Body Potassium ◽  
Males And Females ◽  
Total Body

Total Body Potassium and Body Fat Estimation in Relationship to Height, Sex, Age, Malnutrition and Obesity

1975 ◽  
Vol 48 (5) ◽  
pp. 431-440 ◽  
Author(s):  
C. J. Edmonds ◽  
B. M. Jasani ◽  
T. Smith
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Body Fat ◽  
Fat Free Mass ◽  
Whole Body ◽  
Regression Equations ◽  
Total Body Potassium ◽  
Normal Individuals ◽  
Males And Females ◽  
Total Body

1. Total body potassium was estimated by 40K measurement with a high-sensitivity whole-body counter in normal individuals over a wide age range and in patients who were obese or were grossly wasted as a result of various conditions which restricted food intake. 2. Potassium concentration (mmol/kg body weight) fell with increasing age over 30 years in both normal males and females, but when individuals of different age groups were matched for height, a significant fall in total body potassium with increasing age was observed only in males. Total body potassium of females was about 75% that of males of similar height when young, the sex difference decreasing with ageing. In the normal population, total body potassium was significantly correlated with height and with weight; regression equations for various relationships are given. 3. Fat-free mass was estimated from total body potassium, values of 65 and 56 mmol of potassium/kg fat-free mass being used for males and females respectively. Body fat estimated by this method correlated well with skinfold measurements over a wide range of body weight but in malnourished individuals having inadequate food intake there was considerable discrepancy and present formulae for estimating fat-free mass from total body potassium appear unsatisfactory in malnutrition. Considerable differences between expected and observed values of total body potassium were found in muscular individuals and in normal individuals who were thin but whose body weight was relatively constant. 4. The patients with malnutrition were low both in body fat as estimated by skinfold thickness and in total body potassium estimated on the basis of height. Plasma potassium was, however, normal and potassium supplements did not increase the total body potassium. 5. Total body potassium of obese individuals was not significantly different from that of normal weight individuals on the basis of height. Total body potassium fell on weight reduction with a very low energy diet of 1260 kJ (300 kcal.) daily but changed little with a 3300 kJ (800 kcal.) diet over several months' observation. 6. For overweight, obese individuals, total body potassium was best predicted from the individual's height. For those whose body weight was less than expected, the use of weight gave the best prediction but the error was considerable when the weight deviation was large.

The Measurement of Total Body Potassium in Patients on Peritoneal Dialysis

2001 ◽  
Vol 21 (3_suppl) ◽  
pp. 163-167 ◽  
Author(s):  
Graham Woodrow ◽  
Brian Oldroyd ◽  
Antony Wright ◽  
W. Andrew Coward ◽  
John H. Turney ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Deuterium Oxide ◽  
Cell Mass ◽  
Fat Free Mass ◽  
Whole Body ◽  
Body Cell Mass ◽  
Total Body Potassium ◽  
Noninvasive Technique ◽  
Body Cell ◽  
Total Body

♦ Objectives To assess the validity of measuring total body potassium (TBK) to estimate fat-free mass (FFM) and body cell mass (BCM) in patients on peritoneal dialysis (PD). ♦ Methods We studied 29 patients on PD (14 men, 15 women) and 30 controls (15 men, 15 women). We calculated TBK by using a whole-body counter to measure 1.46 MeV gamma-ray emissions from naturally occurring 40K. We measured total body water (TBW) by deuterium oxide dilution, and extracellular water (ECW) from bromide dilution. These measurements allowed us to estimate intracellular water (ICW), fat-free mass dilution (FFMDilution), and body cell mass dilution (BCMDilution). ♦ Results The FFMTBK in male PD patients (55.7 ± 7.0 kg) did not differ from that in male controls (57.0 ± 10.9 kg). The FFMTBK in female PD patients (38.4 ± 6.8 kg) was less than that in female controls (44.7 ± 4.5, p < 0.01). The FFMDilution did not differ from the FFMTBK. Correlation of FFMTBK and FFMDilution was r = 0.90, p < 0.0001 for all subjects; r = 0.90, p < 0.0001 for PD patients; and r = 0.90, p < 0.0001 for controls. Bland–Altman comparison of FFMDilution with FFMTBK in individuals showed bias 0.6 kg, range –8.5 kg to 9.7 kg for the whole group; bias 1.4 kg, range –7.9 kg to 10.7 kg for PD patients; and bias –0.2 kg, range –9.0 kg to 8.6 kg for controls. The BCMTBK in male PD patients (30.1 ± 4.5 kg) did not differ from that in male controls (31.9 ± 6.2 kg). The BCMTBK in female PD patients (19.0 ± 4.4 kg) was less than that in female controls (23.1 ± 2.9 kg, p < 0.01). The BCMDilution results did not differ from those for the BCMTBK. Correlation of BCMTBK and BCMDilution was r = 0.90, p < 0.0001 for all subjects; r = 0.87, p < 0.0001 for PD patients; and r = 0.93, p < 0.0001 for controls. Bland–Altman comparison of BCMDilution with BCMTBK in individuals showed bias 0.1 kg, range –5.9 kg to 6.1 kg for the whole group; bias 0.0 kg, range –6.9 kg to 6.9 kg for PD patients; and bias 0.1 kg, range –5.0 kg to 5.2 kg for controls. The [K+]ICW did not differ between PD patients and controls (148.0 ± 25.1 mmol/L vs 148.1 ± 14.3 mmol/L, p = nonsignificant). ♦ Conclusions Total body potassium is a valid, noninvasive technique for measuring FFM and BCM in PD patients. In our PD patient group, depletion of FFM and BCM as compared with controls was identified in the women but not in the men.

Magnitude and variation of ratio of total body potassium to fat-free mass: a cellular level modeling study

2001 ◽  
Vol 281 (1) ◽  
pp. E1-E7 ◽  
Author(s):  
Zimian Wang ◽  
F. Xavier Pi-Sunyer ◽  
Donald P. Kotler ◽  
Jack Wang ◽  
Richard N. Pierson ◽  
...  
Keyword(s):  
Body Fat ◽  
Essential Element ◽  
Physiological Model ◽  
Cellular Level ◽  
Fat Free Mass ◽  
Total Body Potassium ◽  
Fluid Compartment ◽  
Total Body Fat ◽  
Total Body ◽  
Living Organisms

Potassium is an essential element of living organisms that is found almost exclusively in the intracellular fluid compartment. The assumed constant ratio of total body potassium (TBK) to fat-free mass (FFM) is a cornerstone of the TBK method of estimating total body fat. Although the TBK-to-FFM (TBK/FFM) ratio has been assumed constant, a large range of individual and group values is recognized. The purpose of the present study was to undertake a comprehensive analysis of biological factors that cause variation in the TBK/FFM ratio. A theoretical TBK/FFM model was developed on the cellular body composition level. This physiological model includes six factors that combine to produce the observed TBK/FFM ratio. The ratio magnitude and range, as well as the differences in the TBK/FFM ratio between men and women and variation with growth, were examined with the proposed model. The ratio of extracellular water to intracellular water ( E/I) is the major factor leading to between-individual variation in the TBK/FFM ratio. The present study provides a conceptual framework for examining the separate TBK/FFM determinants and suggests important limitations of the TBK/FFM method used in estimating total body fat in humans and other mammals.

Letters to the Editor

PEDIATRICS ◽  
1968 ◽  
Vol 41 (6) ◽  
pp. 1147-1148
Author(s):  
John C. Sinclair
Keyword(s):  
Oxygen Consumption ◽  
Cell Mass ◽  
Extracellular Fluid ◽  
Chemical Constituent ◽  
Metabolic Function ◽  
Total Body Potassium ◽  
Letters To The Editor ◽  
Relative Growth ◽  
Total Body

Professor Burmeister, in dealing with problems of relative growth, uses equations of the form Y = a Xh, as proposed by Huxley. Values for the exponent b, in equations of this form, indicate the rate of accretion of the part (organ, chemical constituent, body compartment, metabolic function) in relation to the whole. Values for b of less than one indicate a relatively lesser rate of accretion of the part See Images in the PDF File e.g., our exponent for extracellular fluid, b = 0.80 (Table II of Burmeister's reference 5); values of greater than one indicate a relatively greater rate of accretion of the part–e.g., Burmeister's exponents for total body potassium, 1.09, and for cell mass, 1.11, and ours for resting oxygen consumption, 1.22, and for fat, 2.18 (Table II of Burmeister's reference 5).

Estimation of Non-Fat Body Tissues from Measurements of Skinfold Thickness, total Body Potassium and Total Body Nitrogen

1983 ◽  
Vol 65 (4) ◽  
pp. 407-414 ◽  
Author(s):  
D. B. Morgan ◽  
L. Burkinshaw
Keyword(s):  
Fat Body ◽  
Skinfold Thickness ◽  
Statistical Technique ◽  
Fat Free Mass ◽  
Variable Component ◽  
Total Body Potassium ◽  
Tissue Mass ◽  
Body Tissues ◽  
Total Body ◽  
The Relationship

1. Many previous reports have shown that the ratio of total body potassium to fat-free tissue mass is, on average, higher in men than in women. 2. In an attempt to explain this finding we have re-examined our own data and data taken from the literature. Our own data comprise measurements on 333 healthy people (196 men and 137 women). In all subjects we measured total body potassium and estimated fat-free mass from body weight and skinfold thickness; in 91 of them (62 men and 29 women) we measured, in addition, total body nitrogen. 3. We have used the statistical technique of factor analysis to obtain unbiased estimates of the relationships between the three quantities measured in the smaller group. The validity of the relationships is supported by the results from the larger group and by data from the literature. 4. The average values of total body potassium and fat-free mass are greater in men than in women, but the relationship between the two variables is identical in men and women. The relationship has a positive intercept on the axis of fat-free mass, so that the ratio of total body potassium to fat-free mass increases with fat-free mass. The higher ratio in men compared with women can therefore be explained by a difference in size alone. 5. The relationship between total body potassium and total body nitrogen has a negligible intercept. Therefore the ratio of total body potassium to total body nitrogen does not change with size. 6. These findings suggest that, on average, the fat-free mass is made up of a fixed component of approximately 9 kg of tissue containing no potassium or nitrogen, and a variable component with a potassium to nitrogen ratio of about 1.81 mmol/g.

Hydration of fat-free body in protein-depleted patients

1985 ◽  
Vol 249 (2) ◽  
pp. E227-E233 ◽  
Author(s):  
A. H. Beddoe ◽  
S. J. Streat ◽  
G. L. Hill
Keyword(s):  
Cell Mass ◽  
Protein A ◽  
Extracellular Fluid ◽  
The Body ◽  
Fat Free Mass ◽  
Body Protein ◽  
Mean Values ◽  
Free Body ◽  
Fluid Compartments ◽  
Total Body

It is widely believed that increased hydration of the fat-free body accompanies most major disease processes as a result of contraction of the body cell mass and expansion of the extracellular fluid. Measurements of total body water (TBW) and total body nitrogen in 68 normal volunteers and 95 surgical ward patients presenting for intravenous nutrition have been used to derive ratios of TBW to fat-free mass (TBW:FFM) and protein indices (PI), where PI is defined as the ratio of measured total body protein to predicted TBP. Mean values of PI were 1.009 +/- 0.116 (SD) and 0.783 +/- 0.152 in the normal and patient groups, respectively, corresponding to mean TBW:FFM ratios of 0.719 +/- 0.016 and 0.741 +/- 0.029. However, 48 patients had normal TBW:FFM despite having lost 15% of body protein. A theoretical model of body composition changes in catabolic illness is presented, which is in accord with the patient data, demonstrating that TBW:FFM does not necessarily increase in catabolic illness and that the ratio masks underlying shifts in body fluid compartments.

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