Ensuring quality in 17OHP mass spectrometry measurement: an international study assessing isomeric steroid interference.

Objectives: Interference from isomeric steroids is a potential cause of disparity between mass spectrometry-based 17-hydroxyprogesterone (17OHP) results. We aimed to assess the proficiency of mass spectrometry laboratories to report 17OHP in the presence of known isomeric steroids.

Methods: A series of five samples were prepared using a previously demonstrated commutable approach.

Simultaneous quantitation of urine aldosterone and tetrahydroaldosterone in healthy Chinese subjects using a validated LC-MS/MS method.

Aldosterone (ALD) is excreted in urine mainly as glucuronide conjugates of ALD and tetrahydroaldosterone. Measuring these urinary metabolites might be an alternative screening test to plasma ALD for primary aldosteronism. We report a validated LC-MS/MS method to measure both analytes simultaneously.

Lack of Effects of Renin-Angiotensin-Aldosterone System Activity and Beta-Adrenoceptor Pathway Polymorphisms on the Response to Bisoprolol in Hypertension.

Purpose: This study examined the effects of plasma renin activity (PRA), angiotensin II (Ang II) and aldosterone (PAC) concentrations as well as common polymorphisms in the β-Adrenoceptor gene () and the G-protein α-Subunit (G) protein gene the G protein α-Subunit 1 gene () on the blood pressure (BP) and heart rate (HR) response to bisoprolol in Chinese patients with hypertension.

Methods: Patients with sitting clinic systolic BP (SBP) 140-169 mmHg and/or diastolic BP (DBP) 90-109 mmHg after placebo run-in were treated with open-label bisoprolol 2.5 mg daily for 6 weeks.

Influence of isotopically labeled internal standards on quantification of serum/plasma 17α-hydroxyprogesterone (17OHP) by liquid chromatography mass spectrometry.

Objectives Our recent survey of 44 mass spectrometry laboratories across 17 countries identified variation in internal standard (IS) choice for the measurement of serum/plasma 17α-hydroxyprogesterone (17OHP) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The choice of IS may contribute to inter-method variations. This study evaluated the effect of two common isotopically labeled IS on the quantification of 17OHP by LC-MS/MS.

Performance of a point-of-care device for oral fluid ketamine evaluated by a liquid chromatography-tandem mass spectrometry method.

The performance of a point-of-care device, the OratectXP Oral Fluid Drug Screen Device for Ketamine, was evaluated. The cutoff specification for the device was for ketamine at 15 ng/mL. A total of 72 authentic oral fluid samples were collected from volunteers at two local rehabilitation centers for clients with addiction to drugs of abuse.