Clin. Biochem. 10, (2) 97-98 (1977)

Laboratory

Note

Analysis of Estrogens in Small Samples of Non-Pregnancy Urine MARY G. METCALF Medical Unit, The Princess Margaret Hospital, Christchurch, New Zealand (Accepted December 9, 1976)

RESULTS CLBIA, 10, (2) 97-98 (1977) Clin. Biochem. Metcalf, M. G. Medical Unit, The Princess Margaret Hospital, Christchurch, New Zealand A N A ' L l r S I S OF E S T R O G E N S I N S M A L L SAMPLES OF NON-PREGNANCY URINE 1. In a widely used procedure f o r measuring estrogens in non-pregnancy urine a~, 0.01 to 0.05% of a 24hr specimen is taken for analysis. 2. There is an inverse relationship between 24hr urine volume (Z) and creatinine concentration (81 observations on 75 women; r - - -0.780; ereatinine ( g / l ) _-- 2 . 3 4 - 0 . 8 7 z ( l ) ; P 2.25 ( > 2 0 retool/l) 0.9- 2.25 (8- 20retool/l) 1 liter.

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2.5-

creatinine, 2.25 g/I

or

2.0-

y . 2 . 3 4 - 0.87

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r = -0.780

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IN A COMMONLY USED METHOD f o r m e a s u r i n g e s t r o g e n s i n n o n - p r e g n a n c y u r i n e , i t is r e c o m m e n d e d t h a t

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---4 .creatinine,O.9g/I . . . .

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1 1 t h e a m o u n t t a k e n f o r a n a l y s i s be f r o m 2--6-0-6 to 10,00----0 ( 0 . 0 5 - 0 . 0 1 % ) o f a 2 4 h r u r i n e s p e c i m e n . (1) T h e s e l i m i t s a r e i m p o r t a n t . I f m o r e u r i n e is used, h y d r o l y s i s r e l a t e d d e c o m p o s i t i o n o f t h e e s t r o g e n s increases(=); i f less is used, a s s a y s e n s i t i v i t y is s a c r i f i c e d . A p r o b lem a r i s e s w h e n e s t r o g e n e x c r e t i o n r a t e s a r e to be calc u l a t e d f r o m m e a s u r e m e n t s m a d e on s m a l l s a m p l e s of u r i n e c3). I n t h e a b s e n c e o f a 2 4 h r specimen, t h e choice o f an a p p r o p r i a t e volume o f u r i n e f o r a n a l y s i s m u s t be m a d e on c r i t e r i a o t h e r t h a n t h a t o f 2 4 h r u r i n e o u t p u t . I n t h i s r e p o r t , t h e use o f u r i n a r y c r e a t i n i n e c o n c e n t r a t i o n s f o r t h i s p u r p o s e is d i s c u s s e d . METHODS The concentration of creatinine was measured '~) in 81, 24hr specimens of urine collected from 75 normal mens t r u a n t women. Twenty of the women were t a k i n g oral contraceptive tablets. Their ages ranged from 15 to 49 years (mean +---s t a n d a r d deviation : 28.9 -----lO.ly).

0

0.5'

1.0'

115

x 3.o

24 h r URINE VOLUME ( t )

Fig. I - - Comparison between the volume and ¢reatinine content of ~$hr urine specimens collected from normal menstruant women. DISCUSSION T h e v o l u m e of u r i n e to be t a k e n f o r e s t r o g e n a n a l y s i s can be d e c i d e d on t h e b a s i s o f t h e i n f o r m a t i o n shown in F i g u r e 1. F o r u r i n e s p e c i m e n s c o n t a i n i n g c r e a t i n i n e a t c o n c e n t r a t i o n s a b o v e 2.25 g / l , i t is s u g g e s t e d t h a t 0.20 m] be t a k e n f o r a n a l y s i s ; f o r t h o s e c o n t a i n i n g 0 . 9 - 2 . 2 5 g / / , 0.25 ml should be u s e d ; a n d f o r t h o s e in w h i c h t h e c o n c e n t r a t i o n o f c r e a t i n i n e i s < 0 . 9 g / l , a v o l u m e o f 0.50 ml is r e c o m m e n d e d . A d h e r ence to t h i s r e g i m e g a v e a n a l y t i c a l s a m p l e s c o n t a i n -

98

METCALF ing from 0.01 to 0.05% of each of the 24hr specimens tested (Figure 2). The requirement that creatinine levels be measured involves no extra analytical effort. The same information is necessary if estrogen excretion rates are to be calculated from observations made on small samples of urine "~.

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ACKNOWLEDGEMENTS

This project was supported by grants from the Medical Research Council of New Zealand and the North Canterbury Hospital Board. My thanks are due to the Biochemistry Department at Christchurch Hospital for the creatinine measurements, and to R. Spinks and D. Buchan who prepared the script.

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r, correlation coefficient n, number of pairs of observations

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Q. I[

REFERENCES

t~

FRACTION o f

24hr

URINE

SPECIMEN

F i g . 2 - - H i s t o g r a m s h o w i n g the f r a c t i o n o f a 2 ~ h r u r i n e collection in s a m p l e s w h o s e v o l u m e w a s 0.20 m l w h e n the c r e a t i n i n e c o n c e n t r a t i o n exceeded 2.25 g / l , 0.25 m l f o r crea t i n i n e c o n c e n t r a t i o n s o f 0.9 - 2 . 2 5 g / l , a n d 0.50 m l f o r conc e n t r a t i o n s below 0.9 g / l . S a m p l e s ( 2 $ h r ) w e r e collected ] r o m 75 m e n s t r u a n t w o m e n on 81 occasions.

1. Brown, J. B., MacLeod, S. C., MacNaughtan, C., Smith, M. A., and Smyth, B. (1968). J. E n d o c r i n . 42, 5-15. 2. Brown, J. B., and Blair, H. A. F. (1958). J. E n d o e r i n . 17, 411-424. 3. Metcalf, Mary G., and Hunt, E. G. (1976). Clin. Biochem. 9 (2), 75-77. 4. Chasson, A. L., Grady, H. J., and Stanley, M.A. (1967). A m . J. Cli*~. P a t h . 35, 83-88.

Analysis of estrogens in small samples of non-pregnancy urine.

Clin. Biochem. 10, (2) 97-98 (1977) Laboratory Note Analysis of Estrogens in Small Samples of Non-Pregnancy Urine MARY G. METCALF Medical Unit, The...
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