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Clin Chim Acta. 2008 Oct;396(1-2):86-8. doi: 10.1016/j.cca.2008.06.014. Epub 2008 Jun 19.

A hydrophilic-interaction chromatography tandem mass spectrometry method for quantitation of serum s-adenosylmethionine in patients infected with human immunodeficiency virus.

Author information

1
Department of Lab Medicine, University of California, San Francisco, CA, United States. pwang@tmhs.org

Abstract

BACKGROUND:

s-Adenosylmethionine (SAM)1 has been suggested as a diagnostic test and surrogate marker for Pneumocystis jirovecii pneumonia (PCP) in HIV-positive patients. In this study, we report a robust hydrophilic-interaction liquid chromatography tandem mass spectrometry (LC-MS/MS) assay that can be used to quantitate serum SAM in clinical laboratories.

METHODS:

Proteins in serum samples were precipitated using trichloroacetic acid. The supernatant was separated after centrifugation. D3d3-SAM was added as the internal standard. SAM and d3-SAM were extracted using a mixed-mode cation exchange column. Extracts were dried under nitrogen and reconstituted in H2O and acetonitrile (1:9, vol:vol). HPLC-tandem mass spectrometry analysis was performed with a silica column and multiple reaction monitoring for SAM and d3-SAM.

RESULTS:

The limit of quantitation (LOQ) for SAM was 10 ng/mL. The assay was linear between 10 and 500 ng/mL. Intra-assay coefficient of variation (CV) was 8% and inter-assay CV was 17% at the LOQ. Turnaround time for each specimen was approximately 1 h. Using this method, we found that serum SAM concentration was correlated with fasting status, especially methionine intake. We also measured acute and convalescent serum SAM levels of 8 HIV-positive patients with PCP and non-PCP pneumonia. SAM concentrations in convalescent samples were significantly increased compared to acute levels only in patients with PCP.

CONCLUSIONS:

The LC-MS/MS method had sufficient analytical sensitivity for detecting low levels of SAM found in HIV-infected patients and can be used for quantitative measurements in a clinical laboratory. This method facilitates research and possible clinical application of SAM as a marker for PCP.

PMID:
18619430
PMCID:
PMC2575815
DOI:
10.1016/j.cca.2008.06.014
[Indexed for MEDLINE]
Free PMC Article

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