From Big Medical Encyclopedia

SILBERA-PORTERA METHODS (R. H. Silber; Page of C. Porter) — colorimetric methods of definition of concentration of 17 oxycorticosteroids in a blood plasma and urine. Contents 17 oxycorticosteroids (see) serves in a blood plasma and urine to one of criteria of a functional condition of bark adrenal glands (see) normal and pathologies.

Methods are based on ability of the steroids having a 17,21-dioxyacetonic side chain in a molecule to react quantitatively with phenylhydrazine in acid medium with formation of the painted phenythydrazones (a maximum of absorption at the wavelength of 410 nanometers).

For the first time the method based on this principle was offered for blood in 1950 and for urine in 1954 by Silberom and Porter.

— P. in m the hydrocortisone, a cortisone and 17-oxy-11-cortexone, i.e. so-called chromogens of Silber — Porter, the representing main hormones, produtsirumy by cortical substance of adrenal glands of the person can be defined by S.

In domestic a lab. to practice for definition 17-oksikortikostero-idov in a blood plasma the greatest distribution was gained by S.'s modification — P. of m offered by N. A. Yudayev and Yu. A. Pankov (1958) and accepted in the USSR as the unified method.

Silber's chromogens — Porter extract from urine or a blood plasma chloroform, then a fenilgidrazinovy reactant; concentration of the formed phenythydrazones is defined by spektrofotometrichesk.

Concentration of the free 17 oxycorticosteroids determined by S. — P. of m, in a blood plasma makes from 5 to 20 mkg in 100 ml (from 140 — 550 nmol/l), on average 13 + 2,4 mkg in 100 ml (the 360th nmol/l).

Contents 17-oksikortikoste-roidov in a blood plasma is subject to rhythmic daily fluctuations (the maximum is observed in the morning), to-rye reflect a day-night rhythm of secretory activity of adrenal glands at the person (see. Biological rhythms ).

Pages — - P. are widely used by m for determination of level of excretion of 17 oxycorticosteroids and their metabolites with urine. For domestic clinical diagnostic laboratories the modification of this method offered M. A. Krekhova (1960) is unified. According to this modification in urine define 17 oxycorticosteroids conjugated with glucuronic to - that (see. Glucuronides ) and not conjugated 17 oxycorticosteroids for what urine before extraction is processed beta glucuronidase (see. Glucuronidase ). Normal excretion with urine 17 of oxycorticosteroids fluctuates from 1, 31 to 7,39 mg a day (3,62 — 20,4 µmol a day), i.e. on average 3,7 mg a day (10,3 µmol a day); the free (not conjugated) 17 oxycorticosteroids are allocated with urine in number from 0,04 to 0,28 mg a day (0,11 — 0,77 µmol a day), on average 0,14 mg a day (0,39 µmol a day).

Bibliography: Krekhova M. A. A method of preparation of drug of a r-glucuronide-zy and its use for definition of 17 oxycorticosteroids of urine, Probl. endocrinins. and gormonoter., t. 6, No. 2, page 55, 1960; Yudayev N. A. and Pankov Yu. A. Modification of a method of Sil-ber and Porter for definition of 17-oxy-corticosteroids in plasma of peripheral blood, in the same place, t. 4, No. 2, page 35, 1958, bibliogr.; S i 1 b e r R. H. a. Porter C. C. Determination of 17,21-dihyd-roxy-20-ketosteroids in urine and plasma, J. biol. Chem., v. 210, p. 923, 1954.

V. S. Zelenetskaya.