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Singh, Ravinder

https://orcid.org/0009-0001-6484-1365

Mayo Clinic

Mayo Clinic

Citations 40

Utilities of traditional and novel biomarkers in the management of acute kidney injury
Chen, Li-Sheng, Singh, Ravinder

Critical Reviews in Clinical Laboratory Sciences | December 6, 2019 | Volume: 57 | Issue: 4 | Pages: 215-226

10.1080/10408363.2019.1689916 Get It

Diagnostic Thresholds for Androgen-Producing Tumors or Pathologic Hyperandrogenism in Women by Use of Total Testosterone Concentrations Measured by Liquid Chromatography-Tandem Mass Spectrometry
Sharma, Anu , Kapoor, Ekta , Chang, Alice Y. , Erickson, Dana , Singh, Ravinder

Clinical Chemistry | August 1, 2018 | Volume: 64 | Issue: 11 | Pages: 1636-1645

10.1373/clinchem.2018.290825 Get It

Abstract BACKGROUND Previously defined thresholds for total testosterone (TT) concentrations to screen for androgen-producing tumors (APTs) have used RIA, which can be less accurate in women. We aimed to define diagnostic thresholds to screen for APTs or postmenopausal pathologic hyperandrogenism using TT concentrations measured by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). METHODS We performed a retrospective cohort study on all women with TT ≥3.5 nmol/L and all postmenopausal women presenting with hyperandrogenism between 2004 and 2014 at the Mayo Clinic in Rochester, MN. RESULTS Of the 369 women with TT ≥3.5 nmol/L, 89 were included and subdivided into 3 groups based on their clinical diagnosis [21 (24%), APT; 16 (18%), postmenopausal pathologic hyperandrogenism; 52 (58%), polycystic ovary syndrome]. The source of the APT was more frequently ovarian (81%, n = 17) than adrenal (19%, n = 4). The diagnostic threshold using ROC analysis for TT to identify APT in women with severe biochemical hyperandrogenemia was ≥5.1 nmol/L (sensitivity, 90%; specificity, 81%). In a second analysis of a cohort of postmenopausal women only presenting with symptoms or signs of hyperandrogenism, median TT was significantly higher in the postmenopausal pathologic hyperandrogenism group (APT and ovarian hyperthecosis) vs the idiopathic hyperandrogenism group (4.9 vs 0.8 nmol/L; P < 0.01). In postmenopausal women, the diagnostic threshold for pathologic hyperandrogenism was TT ≥2.2 nmol/L (sensitivity, 100%; specificity, 86%). CONCLUSIONS The diagnostic threshold for TT concentration as measured by LC-MS/MS to identify APT in women with biochemical severe hyperandrogenemia was TT ≥5.1 nmol/L. In postmenopausal women, the diagnostic threshold for pathologic hyperandrogenism was lower (TT ≥2.2 nmol/L).
In Reply
Hines, Jolaine, Grebe, Stefan K., Grebe, Stefan K G, Bancos, Irina , Singh, Ravinder

Clinical Chemistry | May 30, 2018 | Volume: 64 | Issue: 8 | Pages: 1258-1259

10.1373/clinchem.2018.290205 Get It

Niche point-of-care endocrine testing – Reviews of intraoperative parathyroid hormone and cortisol monitoring
Chen, Li-Sheng, Singh, Ravinder

Critical Reviews in Clinical Laboratory Sciences | January 23, 2018 | Volume: 55 | Issue: 2 | Pages: 115-128

10.1080/10408363.2018.1425975 Get It

Detection of IGF-1 Protein Variants by Use of LC-MS with High-Resolution Accurate Mass in Routine Clinical Analysis
Hines, Jolaine, Ketha, Hemamalini , Grebe, Stefan K., Milošević, Dragana , Taylor, Robert L. , Algeciras‐Schimnich, Alicia , Singh, Ravinder

Clinical Chemistry | April 28, 2015 | Volume: 61 | Issue: 7 | Pages: 990-991

10.1373/clinchem.2014.234799 Get It

Mass Spectrometric Immunoassay Raises Doubt for the Existence of Parathyroid Hormone Fragment 7–84
Hines, Jolaine M., Lopez, Mary F., Krastins, Bryan, Hoofnagle, Andrew N. , Singh, Ravinder

Clinical Chemistry | January 18, 2015 | Volume: 61 | Issue: 3 | Pages: 558-560

10.1373/clinchem.2014.235440 Get It

Urinary fluticasone propionate-17beta-carboxylic acid to assess asthma therapy adherence
Hagan, John B., Netzel, Brian C., Matthews, Marc R. , Korpi‐Steiner, Nichole , Matthews, Marc R. , Singh, Ravinder , Matthews, Marc R

Allergy and Asthma Proceedings | July 25, 2012 | Volume: 33 | Issue: 4 | Pages: 35-39

10.2500/aap.2012.33.3568 Get It

Ionic Cross Talk Can Lead to Overestimation of 3-Methoxytyramine during Quantification of Metanephrines by Mass Spectrometry
Twentyman, Jolaine M, Cradic, Kendall W, Grebe, Stefan K. , Singh, Ravinder

Clinical Chemistry | May 5, 2012 | Volume: 58 | Issue: 7 | Pages: 1156-1158

10.1373/clinchem.2012.186601 Get It

Measurement of Late-Night Salivary Cortisol and Cortisone by LC-MS/MS to Assess Preanalytical Sample Contamination with Topical Hydrocortisone
Raff, Hershel , Singh, Ravinder

Clinical Chemistry | March 1, 2012 | Volume: 58 | Issue: 5 | Pages: 947-948

10.1373/clinchem.2012.182717 Get It

Urine sugars for in vivo gut permeability: validation and comparisons in irritable bowel syndrome-diarrhea and controls
Rao, Archana S., Camilleri, Michael , Eckert, Deborah J., Busciglio, Irene, Burton, Duane D. , Ryks, Michael, Wong, Banny S., Lamsam, Jesse, Zinsmeister, Alan R., Singh, Ravinder

American Journal of Physiology-Gastrointestinal and Liver Physiology | August 12, 2011 | Volume: 301 | Issue: 5 | Pages: G919-G928

10.1152/ajpgi.00168.2011 Get It

Mucosal barrier dysfunction contributes to gastrointestinal diseases. Our aims were to validate urine sugar excretion as an in vivo test of small bowel (SB) and colonic permeability and to compare permeability in patients with irritable bowel syndrome-diarrhea (IBS-D) to positive and negative controls. Oral lactulose (L) and mannitol (M) were administered with 99m Tc-oral solution, 111 In-oral delayed-release capsule, or directly into the ascending colon (only in healthy controls). We compared L and M excretion in urine collections at specific times in 12 patients with IBS-D, 12 healthy controls, and 10 patients with inactive or treated ulcerative or microscopic colitis (UC/MC). Sugars were measured by high-performance liquid chromatography-tandem mass spectrometry. Primary endpoints were cumulative 0–2-h, 2–8-h, and 8–24-h urinary sugars. Radioisotopes in the colon at 2 h and 8 h were measured by scintigraphy. Kruskal-Wallis and Wilcoxon tests were used to assess the overall and pairwise associations, respectively, between group and urinary sugars. The liquid in the colon at 2 h and 8 h was as follows: health, 62 ± 9% and 89 ± 3%; IBS-D, 56 ± 11% and 90 ± 3%; and UC/MC, 35 ± 8% and 78 ± 6%, respectively. Liquid formulation was associated with higher M excretion compared with capsule formulation at 0–2 h (health P = 0.049; IBS-D P < 0.001) but not during 8–24 h. UC/MC was associated with increased urine L and M excretion compared with health (but not to IBS-D) at 8–24 h, not at 0–2 h. There were significant differences between IBS-D and health in urine M excretion at 0–2 h and 2–8 h and L excretion at 8–24 h. Urine sugars at 0–2 h and 8–24 h reflect SB and colonic permeability, respectively. IBS-D is associated with increased SB and colonic mucosal permeability.