The distribution of body water

Letters to the editors

144

4. GU~TA N. K., BHOLA G. C., GUPTA S., KALRA K. and GUPTA M. M. Indian J. med. Res. 61, 105-l 08 (1973). 5. CO~RALL M. F., STRINGER A. M. and TROTT und N. G. Radioaktive Isotope in Klinik Forschung 8, pp. 122-137. Urban and Schwarzenberg, Munchen (1968).

International

Journal

pp. 144-145.

Pergamon

of

Nuclear

Medicine

and

Press. Printed in Northern

Biology,

1977,

Vol.

4,

Ireland

nearest integer or a value just in between, compared with the proposed ones.

when

This Relationship Seems to be More than Casual The theoretical foundation achieved by these observations, on the other hand, leads towards fertile ground for a series of hypotheses to explore and test. Tentatively, the distribution of percentages of the body water in ascending order is as follows: exp(1)+3exp(2)+exp(3)+exp(4)+C,=lOO. (1)

The Distribution of Body Water (Received 30 November 1976) WORK with different body compartments(“‘) and their respective water content forcibly leads towards the knowledge of a given set of established mean values belonging to these. A search in the corresponding literature reveals fairly good agreement. The values of a well-known and accepted source have been reproduced amongst other things on Table 1.(3’The purpose of this communication is to indicate as a relationship a certain set of magnitudes which offer the most striking resemblances and which facilitate an evaluation of ciphers to be expected. The second column of Table 1, for instance, reproduces the information for the normal young male pertaining to the percentages of total body water. The third column shows what shall be termed proposed values and the next column explains their origin and meaning. This is carried out again for the corresponding percentages of body weight and is represented in the last three columns. It should be noted and emphasized that the given numbers from the reference, without exception, represent the best approximation: either to the TABLE 1. Water distribution, % Total body water Allocation Plasma Interstitial lymph Dense connective tissue and cartilage Inaccessible bone water Transcellular Total extracellular Total intracellular Necessary constant Total body water

Ref. 3

Proposed

20.0

7.3891 20.0855

1.5 7.5 2.5 45.0 55.0 -

7.3891 7.3891 2.7183 44.9710 54.5980 0.4310

100.0

100.0000

1.5

Here C1 stands for a small fraction, necessary to add up to 100%. The meaning of the other expressions can be deduced from Table 1. To establish the equation for the percentages of the body weight distribution, equation (1) is divided by Je, leading to: exp (s) + 3 exp ($) + exp ($) + exp (i) + C, = 60.653 1 (2) naturally: C, = C&e;

C, = 0.2615.

The first author of this communication, in a recent study on young adults@’ to determine total water, found an average of 64.962% for men and 56.661% for women. The average is 60.786%, very close to the theoretical 60.6531%. Other author#’ of recognized authority indicate the respective ciphers as being 61.1 and 51.2% in a study performed with deuterated water for men and women, respectively. The pertinent considerations to the variations encountered are of a statistical nature on one hand and methodological on the other. In the future, more measurements will become available, with

comparing established and proposed values Origin of given value

exp (2) exp (3) exp (2) exp (2) exp (1) Sum of above exp (4) Difference from 100% Sum of terms

% Body weight Proposed Ref. 3 4.5 12.0

4.4817 12.1825

4.5 4.5 1.5 27.0 33.0 -

4.4817 4.4817 1.6487 21.2763 33.1154 0.2615

60.0

60.6531

Origin of given value

exp($1 exp

(2)

exp (f) exp ($ exp (2) Sum of above exp G) Difference from lOO/exp (4) lOO/exp (4)

Letters to the editors ever-increasing accuracy, to shed more light on the true meaning of the presented theoretical material. It should, furthermore, be kept in mind that a tracer has its own dynamics, possibly due to the isotopic effect. The determinations for total body water using urine show systematic small differencesc4) when compared to those from plasma or serum. Another related matter which requires special attention relates to the exact water content within the different body fluids, thus introducing possible misinterpretations. More information in this regard is certainly needed. A more detailed knowledge of the facts considered above will hopefully disclose whether formulae (lj and (2) are correct for males only, or represent an average. It is foreseeable that some small correction factor is needed to predict a definitive value for either sex or for females only. The fundamental question of course will presently remain as a challenge; to prove or disprove the suspected relationships with the base of the

145

natural logarithms, and if it does stand the physiological meaning.

exist,

to under-

P. L. EBERSTAW J. J. Coo Centro de Estudios Nucleares, Universidad National Autbnoma Mixico 20, D.F.

de Mkxico,

References 1. &zRsrADT P. L. and Coo J. J. Int. J. nucl. Med. Biol. 2, 99-106 (1975). 2. BROWNELL G.L.,BERMAN M.and ROBERTSON J.S. ht. .I. appl. Radiat. Isotopes 19, 249-262 (1968). 3. EDELMAN I.S.and LEIBMAN J.Am..I. Med. 27, 256-277 (1959). 4. ERERSTADT P. L. Int.J. nucl. Med. Biol. 1, 191-195 (1974). 5. EDELMAN I.S.,HALEY H.B.,SCHLOERB P. R..

SHELDON D. B.,FRIIs-HANSEN B.J.,STOL~.G. and MOORE F. D. Surgery Gynec. Obstet. 95, l-l:!(1952).