31 May 2018 Rapid spectrophotometric quantification of urinary porphyrins and porphobilinogen as screening tool for attacks of acute porphyria
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Abstract
Autosomal-dominant acute porphyria, a group of rare diseases, can lead to life-threatening neurovisceral attacks. No efficient screening test is available today. Elevated urinary porphobilinogen in addition to elevated porphyrins is highly specific for an attack of acute porphyria. This study proposes and evaluates a custom-made device, algorithm, and methods for a two-step quantification of urinary porphyrins and porphobilinogen. The first step is oxidation of the nonfluorescent porphyrinogens and subsequent fluorescence-spectroscopic determination of total urinary porphyrins (TUP) using second derivative spectral fitting. Photo-oxidation is compared with chemical oxidation methods. The second step is the quantification of porphobilinogen in case of elevated TUP. Heat-induced conversion products of porphobilinogen, namely uroporphyrin and porphobilin, are quantified by fluorescence and absorption spectroscopy. Results show that the preferred method combination is TUP quantification (lower limit of quantification: 0.2  μmol  /  L) after photo-oxidation with subsequent absorption-spectroscopic determination of porphobilin after heating for indirect quantification of porphobilinogen (quantification range: 0 to 20  mg  /  L). Urinary porphobilinogen and porphyrins of one acute porphyria patient were quantified with <10  %   deviation from an external reference determination. The spectrophotometric approach requires only minimal sample processing and yields a result within 15 min, thus closing the screening gap for acute porphyria.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)
Alexander Lang, Alexander Lang, Christian Heckl, Christian Heckl, Michael Vogeser, Michael Vogeser, Thomas Stauch, Thomas Stauch, Christian Homann, Christian Homann, Georg Hennig, Georg Hennig, Ronald Sroka, Ronald Sroka, Herbert Stepp, Herbert Stepp, } "Rapid spectrophotometric quantification of urinary porphyrins and porphobilinogen as screening tool for attacks of acute porphyria," Journal of Biomedical Optics 23(5), 055006 (31 May 2018). https://doi.org/10.1117/1.JBO.23.5.055006 . Submission: Received: 8 March 2018; Accepted: 11 May 2018
Received: 8 March 2018; Accepted: 11 May 2018; Published: 31 May 2018
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