Publications by authors named "Teresa Kam Chi Tsui"

4 Publications

  • Page 1 of 1

Quantitation of plasma angiotensin II in healthy Chinese subjects by a validated liquid chromatography tandem mass spectrometry method.

Biomed Chromatogr 2022 Jan 3:e5318. Epub 2022 Jan 3.

Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Statin, NT, Hong Kong.

Introduction: Quantitation of plasma angiotensin (Ang) II, the active mediator of the renin-angiotensin system (RAS), is challenging due to its low physiological concentration. We report a validated liquid chromatography-mass spectrometry (LCMS) method to overcome this challenge.

Method: Ang II was extracted from EDTA plasma by an offline solid-phase extraction procedure with Waters MAX μElution plate. LCMS quantitation was performed on the Waters TQS system, monitoring the 3+ ions of the peptide. The analytical performance of the LCMS method was validated. The stability of Ang II was studied with or without the presence of a protease inhibitor. Local reference intervals were established from 143 healthy normotensive subjects (57% female, 21-60 years old).

Results: The Ang II LCMS method had a measurable range of 3.3 - 700 pmol/L. Between batch precision coefficient of variation was <7% over the Ang II concentrations of 8.6 - 110 pmol/L. No significant matrix interference and carryover was observed. There was no significant difference in Ang II concentration in EDTA blood and plasma for at least 2 hours and 1 hour at room temperature, respectively. Ang II was stable for at least one year when stored at -80 C, with or without the protease inhibitor. Age-dependent Ang II reference intervals were established: 4.4-17.7 pmol/L (21-30 years) and 3.9-12.8 pmol/L (31-60 years).

Conclusion: The present LCMS method is suitable for quantitation of Ang II to study the RAS system. Ang II collected at room temperature into EDTA bottles was stable at -80 C for at least 1 year. The first age-dependent reference intervals of plasma Ang II were established for a healthy normotensive Chinese population.
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January 2022

A Hong Kong Chinese kindred with familial hypocalciuric hypercalcaemia caused by mutation.

F1000Res 2019 9;8:1612. Epub 2019 Sep 9.

Department of Chemical Pathology, Prince of Wales Hospital, Shatin, Hong Kong.

Familial hypocalciuric hypercalcaemia (FHH) is a genetic disorder of altered calcium homeostasis. Mutations in the , and genes have been reported to cause FHH. We report a Hong Kong Chinese kindred with FHH type 3 (FHH3) caused by mutations in . The proband, a 51-year-old woman with hypercalcaemia, was initially diagnosed to have primary hyperparathyroidism but repeated parathyroidectomy failed to normalize her plasma calcium concentrations. Later, FHH was suspected and yet no mutations were identified in the gene which causes FHH type 1 (FHH1), the most common form of FHH. Genetic testing of revealed a heterozygous c.43C>T (p.Arg15Cys) mutation, confirming the diagnosis of FHH3. The elder brother and niece of the proband, who both have hypercalcaemia, were found to harbour the same mutation. To our knowledge, this is the first Chinese kindred of FHH3 reported in the English literature.
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June 2020

Aldosterone-producing Adenoma in Primary Aldosteronism: CT-guided Radiofrequency Ablation-Long-term Results and Recurrence Rate.

Radiology 2016 Nov 27;281(2):625-634. Epub 2016 May 27.

From the Departments of Surgery (S.Y.W.L., S.K.H.W., P.W.Y.C., E.K.W.N.), Diagnostic Radiology and Organ Imaging (C.C.M.C.), Chemical Pathology (T.K.C.T.), and Medicine and Therapeutics (A.P.S.K., F.C.C.C.), Faculty of Medicine, Prince of Wales Hospital, Chinese University of Hong Kong, 30-32 Ngan Shing St, Shatin, New Territories, Hong Kong, SAR.

Purpose To evaluate the long-term biochemical, clinical, and recurrence outcomes of radiofrequency (RF) ablation in treating primary aldosteronism due to aldosterone-producing adenoma (APA). Materials and Methods Institutional review board approval and written informed consent were obtained. The use of computed tomographically (CT) guided percutaneous RF ablation was evaluated in 36 patients (19 men; mean age ± standard deviation, 52.1 years ± 10.4) with APA (17 right and 19 left side; mean size, 15.5 mm ± 5.0). Primary aldosteronism was confirmed by using the oral sodium-loading test. After RF ablation, CT images, aldosterone-to-renin ratio (ARR), serum potassium level, and blood pressure control were assessed at 3 months and at the latest follow-up examination. Long-term treatment success was defined as normalization of ARR at the latest assessment. Comparison of ARR, potassium, and blood pressure levels before and after RF ablation was performed by using the Wilcoxon signed-rank test. Results Primary technical success was achieved in 33 (92%) patients who underwent a single RF ablation session. Secondary technical success was achieved in three (8%) patients who required a second RF ablation. At 3-month follow-up, primary aldosteronism was resolved in 33 (92%) patients, with a starting median ARR of 8583 pmol/L per µg/(L · h) that normalized to 97 pmol/L per µg/(L · h) (P < .01). Mean serum potassium levels increased from 2.6 mmol/L ± 0.4 to 4.0 mmol/L ± 0.3 (P = .01). At long-term follow-up (mean, 6.2 years ± 2.5), treatment success was maintained in 33 patients (92%), all of whom had ARRs in the normal range (P < .01). The long-term recurrence rate was 0%. Hypokalemia was resolved in all patients (2.6 mmol/L ± 0.4 to 4.1 mmol/L ± 0.3, P = .01). Hypertension was resolved in 13 (36%) patients, and its control was improved in seven (19%) patients. One (3%) patient had major complications and six (17%) had minor complications. Conclusion CT-guided RF ablation is an effective treatment for APA, with high sustainable long-term treatment success. It may serve as a justifiable treatment alternative to surgery and medical therapy for APA. RSNA, 2016.
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November 2016

Diagnosis of 5α-reductase 2 deficiency: is measurement of dihydrotestosterone essential?

Clin Chem 2013 May 19;59(5):798-806. Epub 2013 Mar 19.

Division of Clinical Biochemistry, Queen Mary Hospital, Hong Kong SAR.

Background: 5α-Reductase 2 deficiency (5ARD) is a known cause of 46,XY disorders of sex development (DSD). Traditionally, the diagnosis relies on dihydrotestosterone (DHT) measurement, but the results are often equivocal, potentially leading to misdiagnosis. We reviewed alternative approaches for diagnosis of 5ARD.

Methods: We conducted a retrospective review of the results of urinary steroid profiling (USP) by GC-MS and mutational analysis of SRD5A2 [steroid-5-alpha-reductase, alpha polypeptide 2 (3-oxo-5 alpha-steroid delta 4-dehydrogenase alpha 2)] by PCR and direct DNA sequencing of all 46,XY DSD patients referred to our laboratory with biochemical and/or genetic findings compatible with 5ARD. We also performed a literature review on the laboratory findings of all 5ARD cases reported in the past 10 years.

Results: Of 16 patients diagnosed with 5ARD between January 2003 and July 2012, 15 underwent USP, and all showed characteristically low 5α- to 5β-reduced steroid metabolite ratios. Four patients had DHT measured, but 2 did not reach the diagnostic cutoff. In all 12 patients who underwent genetic analysis, 2 mutations of the SRD5A2 gene were detected to confirm the diagnosis. Twenty-four publications involving 149 patients with 5ARD were published in the review period. Fewer than half of these patients had DHT tested. Nearly 95% of them had the diagnosis confirmed genetically.

Conclusions: 5ARD can be confidently diagnosed by USP at 3 months postnatally and confirmed by mutational analysis of SRD5A2. Interpretation of DHT results may be problematic and is not essential in the diagnosis of 5ARD. We propose new diagnostic algorithms for 46,XY DSD.
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May 2013