Lawrence Mcmahon

Prof. Lawrence Mcmahon

Eastern Health Clinical School, Monash University, Clayton, VIC, Australia

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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4 March 2010 in Obstetric Medicine
Verified
Journal Article
Closed access
LMLawrence Mcmahon
Lawrence Mcmahon
Iron deficiency (ID) and related anaemia (IDA) during pregnancy are highly prevalent worldwide in both developed and developing nations although the causes are often different. At conception, many women lack sufficient iron stores to meet the increased requirements of pregnancy, which are calculated at approximately 1200 mg. Appraisal of iron status in pregnant women is problematic, however the most reliable available diagnostic test is a serum ferritin < 20 µg/L. ID is often associated with other nutritional disorders, and there is frequently a secondary cause or association. A greater oral intake is usually insufficient to meet the increased demands of pregnancy, however regular oral supplements (given either daily or intermittently) can often meet maternal needs and avoid associated neonatal complications of IDA. Over-treatment with iron should be avoided, but intravenous administration is useful when deficiency is discovered late, is severe, or if the woman is intolerant of oral formulations. This paper reviews the current literature, and addresses differences in the prevalence and causes of ID betwen developed and developing nations. It examines gestational iron requirements, distinguishes between ID and IDA, and highlights difficulties in diagnostic testing. Finally, it appraises the evidence for and against different treatment regimens, ranging from food fortification to intravenous iron infusions, according to availability and to need.

16 November 2016 in BMC Nephrology
Verified
Journal Article
Open access
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MRMatthew A. Roberts
Matthew A. Roberts
LHLouis Huang
Louis Huang
DLDarren Lee
Darren Lee
RMRobert MacGinley
Robert MacGinley
STStefanie M. A. Troster
Stefanie M. A. Troster
LMLawrence Mcmahon
Lawrence Mcmahon
Intravenous iron affects serum levels of intact fibroblast growth factor-23 (iFGF23) and its cleavage product c-terminal FGF23 (cFGF23) in iron-deficient people with normal renal function. We hypothesized that intravenous iron modulates iFGF23 and cFGF23 in haemodialysis patients differently according to the type of iron used. Prevalent, stable haemodialysis patients requiring protocol-based intravenous iron therapy were randomized to a single 200 mg dose of either ferric carboxymaltose (FCM) or iron sucrose (IS). The primary outcome was change in iFGF23 and cFGF23 from pre-infusion to Day 2 post-infusion. Serum hepcidin, ferritin and phosphate were also measured. Pair-wise comparisons utilised the Wilcoxon rank sum test; linear mixed models with an interaction term for treatment and time evaluated between-group effects. Forty-two participants completed the study. In those randomized to FCM (n = 22), median (interquartile range) values pre-infusion and Day 2, respectively, were 843 pg/mL (313–1922) and 576 pg/mL (356–1296, p = 0.05) for iFGF23, 704RU/mL (475–1204) and 813RU/mL (267–1156, p = 0.04) for cFGF23, and 1.53 mmol/L (1.14–1.71) and 1.37 (1.05–1.67, p = 0.03) for phosphate. These parameters did not change following IS. Both serum ferritin (p < 0.001) and hepcidin (p < 0.001) increased in both groups, and the increase in hepcidin was greater in the FCM group (p = 0.03 for between-group difference). Contrary to iron-deficient people with normal renal function, haemodialysis patients given protocol-driven intravenous FCM demonstrated a fall in iFGF23 and a rise in cFGF23, changes not evident with IS. This suggests a differential effect of intravenous iron treatment according to both formulation and renal function. Australian and New Zealand Clinical Trials Register ACTRN12614000548639 . Registered 22 May 2014 (retrospectively registered).

11 September 2017 in BMC Nephrology
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Journal Article
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MCMatthew J. Clarkson
Matthew J. Clarkson
SFSteve F. Fraser
Steve F. Fraser
PBPaul N. Bennett
Paul N. Bennett
LMLawrence Mcmahon
Lawrence Mcmahon
CBCatherine Brumby
Catherine Brumby
SWStuart Warmington
Stuart Warmington
Exercise during haemodialysis improves strength and physical function. However, both patients and clinicians are time poor, and current exercise recommendations add an excessive time burden making exercise a rare addition to standard care. Hypothetically, blood flow restriction exercise performed during haemodialysis can provide greater value for time spent exercising, reducing this time burden while producing similar or greater outcomes. This study will explore the efficacy of blood flow restriction exercise for enhancing strength and physical function among haemodialysis patients. This is a randomised controlled trial design. A total of 75 participants will be recruited from haemodialysis clinics. Participants will be allocated to a blood flow restriction cycling group, traditional cycling group or usual care control group. Both exercising groups will complete 3 months of cycling exercise, performed intradialytically, three times per week. The blood flow restriction cycling group will complete two 10-min cycling bouts separated by a 20-min rest at a subjective effort of 15 on a 6 to 20 rating scale. This will be done with pressurised cuffs fitted proximally on the active limbs during exercise at 50% of a pre-determined limb occlusion pressure. The traditional cycling group will perform a continuous 20-min bout of exercise at a subjective effort of 12 on the same subjective effort scale. These workloads and volumes are equivalent and allow for comparison of a common blood flow restriction aerobic exercise prescription and a traditional aerobic exercise prescription. The primary outcome measures are lower limb strength, assessed by a three repetition maximum leg extension test, as well as objective measures of physical function: six-minute walk test, 30-s sit to stand, and timed up and go. Secondary outcome measures include thigh muscle cross sectional area, body composition, routine pathology, quality of life, and physical activity engagement. This study will determine the efficacy of blood flow restriction exercise among dialysis patients for improving key physiological outcomes that impact independence and quality of life, with reduced burden on patients. This may have broader implications for other clinical populations with similarly declining muscle health and physical function, and those contraindicated to higher intensities of exercise. Australian and New Zealand Clinical Trial Register: ACTRN12616000121460.


10 November 2009 in Nephrology Dialysis Transplantation
Verified
Journal Article
Open access
PDF file
LMLawrence Mcmahon
Lawrence Mcmahon
AKAnnette B. Kent
Annette B. Kent
PKPeter G. Kerr
Peter G. Kerr
HHHelen G. Healy
Helen G. Healy
AIAshley Irish
Ashley Irish
SRSimon D. Roger
Simon D. Roger
Background. An optimal haemoglobin (Hb) response to erythropoietin requires elevated iron indices in dialysis patients; however, it is unknown if the same applies in chronic kidney disease (CKD). Methods. One hundred patients [CKD Stages 3–5, Hb ≥ 110 g/L, iron replete, erythropoietin-stimulating agent (ESA)-naive, 47% diabetic, median age 69.5 years] were block-randomized in an open-label study to receive up to 200 mg intravenous iron sucrose (Group A, n = 52) bimonthly or oral iron sulphate (Group B) to maintain raised and normal iron indices (respectively) over 12 months. The primary endpoint was the change in Hb concentration at 12 months or at termination after at least 6 months of treatment. Results. Eighty-five patients reached the primary endpoint (43, Group A; 42, Group B). Initial Hb was 119 ± 7 vs 116 ± 12 g/L (mean ± standard deviation); ferritin 122 (71–176), median (inter-quartile range), vs 90 µg/L (58–150); transferrin saturation (TSat) 22 (18–26) vs 21% (15–24); and creatinine 240 (195–313) vs 230 µmol/L (184–352). Ferritin and TSat differed by month 2 [157 (103–220) vs 96 µg/L (73–162), P = 0.003] and month 6 [25 (20–31) vs 21% (17–27), P = 0.02], respectively. At study end, Hb did not differ between groups (121 ± 10 vs 117 ± 13 g/L). Ferritin was 362 (310–458) vs 125 µg/L (84–190), P < 0.001; TSat 30 (23–34) vs 21% (18–24), P < 0.001; and creatinine 229 (188–326) vs 272 µmol/L (195–413), P = NS. For patients (Groups A and B, n = 27 in each group) whose creatinine regression slope increased (indicating worsening function), the fall in Hb over 12 months also did not differ between groups despite adequate separation in iron indices. Serious adverse events overall did not differ between groups. Conclusions. Elevated iron indices did not increase Hb synthesis in ESA-naive, iron replete, pre-dialysis patients with Hb >110 g/L.

10 December 2010 in Journal of Artificial Organs
Verified
Journal Article
Closed access
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SBSanjeev Baweja
Sanjeev Baweja
KWKate Wiggins
Kate Wiggins
DLDarren Lee
Darren Lee
SBSusan Blair
Susan Blair
MFMargaret Fraenkel
Margaret Fraenkel
LMLawrence Mcmahon
Lawrence Mcmahon