Convenient chromatographic prepurification step before measurement of urinary cortisol by radioimmunoassay.
نویسندگان
چکیده
We applied various prepurification protocols (extraction with different solvents, liquid/solid separation on bonded silica media, Celite, and Sephadex LH20 chromatography) with a range of commercially available RIA kits to measure cortisol in urine samples. We then compared the results with the concentrations measured by a HPLC method validated with reference to isotope dilution gas chromatography-mass spectrometry. We conclude that chromatography on a commercial, prepacked diol minicolumn (Waters Sep-Pak Vac RC) in combination with dichloromethane extraction is a convenient and very effective purification step before RIA of urinary cortisol in patients not receiving corticoid medication. We tested numerous steroids for interference and found that free polar cortisol derivatives (hydroxylated or hydrogenated) could only partially account for the overestimations routinely encountered when free urinary cortisol concentrations are measured by direct RIA.
منابع مشابه
Radioimmunoassay and lipid-chromatographic analysis for free cortisol in urine compared with isotope dilution--mass spectrometry.
I compared results by three different routine methods for analysis for urinary cortisol with those by a highly specific reference method based on isotope dilution--mass spectrometry (i). A "high-performance" liquid-chromatographic method (II) gave the most comparable results (regression coefficient 0.86, intercept 9 nmol/L). For some urines much lower values were obtained by I than by II. Two r...
متن کاملA specific, non-chromatographic radioimmunoassay for human plasma cortisol.
A radioimmunoassay technique has been developed for the measurement of cortisol in a single methylene chloride extract of human plasma without chromatography. The antiserum, obtained by immunizing rabbits with cortisol-3-carboxymethyl-oxime conjugated to bovine serum albumin, had a high affinity (KA = 1.8 X 10(9) 1/mole) and capacity (2.3 X 10(-6) moles/L undiluted serum) for cortisol. The mini...
متن کاملOne-step synthesis of a cortisol derivative for radioiodination and application of the 125I-labeled cortisol to radioimmunoassay.
A one-step synthesis of a cortisol derivative for radioiodination is presented. The radioimmunoassay for cortisol using the bridge heterologous 125I-labeled antigen was more sensitive than that using a bridge homologous antigen. Cortisol levels in saliva and serum were easily determined by direct radioimmunoassay with the proposed 125I-labeled antigen.
متن کاملA procedure for the measurement of urinary 17-hydroxycorticosteroids, aldosterone acid-labile conjugate, and free plasma cortisol in patients with chronic illness.
The usualstepsfor steroid isolationare: (1) hydrolysis,acid for the urinary acid-labile aldosterone conjugate, and enzymatic for the urinary 17-hydroxycorticosteroids (17-OHCS); (2) organic solvent extraction of the corticosteroids; and (3) alkaline, acid, and aqueouswashing of the organic extracts of steroids. In the method described the crude extracts are purified by 3 or 4 sequential partiti...
متن کاملTwo-cycle liquid-chromatographic quantitation of cortisol in urine.
When the free cortisol in urine was analyzed by liquid chromatography after pretreatment with the usual organic extraction, interfering substances having chromatographic behavior similar to that of cortisol and the internal standard precluded accurate measurement. To remove these materials, we processed the organic extract by liquid chromatography with a normal-phase column for clean-up; the sp...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Clinical chemistry
دوره 43 5 شماره
صفحات -
تاریخ انتشار 1997