Mechanism of Reduction of Total Body Potassium in Malnutrition
Lean Body Mass (LBM) consists of tissues which are metabolically active and are responsible for locomotion. In addition, circulation, respiration and metabolism, are all dependent upon the functional activity of the LBM. It is not surprising, therefore, that in nutritional studies an estimation of LBM becomes of great importance. LBM is the main reservoir of body protein and nitrogen. Unfortunately, direct measurement of total body nitrogen (TBN) was not possible until recently: consequently, indirect methods were used to estimate LBM. Analytical data suggested that in healthy muscle the ratio of intracellular potassium to nitrogen is closely controlled at 3 mM K+ to 1 g nitrogen. This ratio was extrapolated to the whole body measurements by using total body potassium (TBK) as an index of body cell mass (BCM) (Forbes and Hursh, 1963) and calculating LBM from these data. Later prompt gamma analysis (PGA) became available to measure total body nitrogen (TBN) (Mernagh et al., 1977); using these techniques, and also carcass analysis, the ratio of TBK to TBN in normals and in a chronically wasted individual (Knight et al., 1986) was found to be 1.6 mM K+/g nitrogen.
KeywordsAnorexia Nervosa Total Parenteral Nutrition Soleus Muscle Free Energy Change Body Cell Mass
Unable to display preview. Download preview PDF.
- Darnell, J., Lodish, H., and Baltimore, D., 1986 Molecular cell biology, Scientific American Books, New YorkGoogle Scholar
- Forbes, C.M., and Hursh. J.M., 1963, Age and sex trends in lean body mass calculated from 40K measurements. Ann. NY Acad. Sci., 110:225.Google Scholar
- Kammermeier, H., 1987, Interrelationship between the free energy change of ATP-hydrolysis, cystolic inorganic phosphate and cardiac performance during hypoxia and reoxygenation, Biomed. Biochim. Acta., 8:S 499.Google Scholar
- Knight, G.S., Beddoe, A.H., Streat, S.J., et al., 1986, Body composition of two human cadavers by neutron activation and chemical analysis, Am. J. Physiol, 250:E179–185.Google Scholar
- Pichard, C., Vaughan, C., Struk, R., Armstrong, R.L., and Jeejeebhoy, K.N., 1988, The effect of dietary manipulations (fasting, hypocaloric feeding and subsequent refeeding) on rat muscle energetics as assessed by nuclear magnetic resonance spectroscopy, J. Clin. Invest., 82: 895–901.PubMedCrossRefGoogle Scholar
- Pichard, C., and Jeejeebhoy, K.N, 1989, Intracellular Potassium (K+) and Membrane Potential in rat muscle during malnutrition and refeeding studied in vivo by K+-Sensitive nicroelectrode (KISE) and by atomic absorption spectrophometry (AAS), Clin. Nutr., 8:51, 1989.Google Scholar
- Report of the Task Group on Reference Man. International Commission on Radiological Protection Report Mo. 23. 1975. Pergamon Press. Oxford.Google Scholar
- Shike, M., Russell, D.McR., Dotsky. A.S., Harrison, J.E., McNeill, K.C., Shepherd, F.A., Feld, R., Evans, W.K., and Jeejeebhoy. K.N., 1984, Changes In body composition in patients with small-cell lung cancer. Ann, Intern. Med. 101: (3), 303–309.Google Scholar