Obese men have lower serum prostate-specific antigen (PSA) than comparably aged lean men, but the underlying mechanism remains unclear. The aim of this study was to determine the effect of obesity on PSA and the potential contributing mechanisms. A cohort of 1195 men aged 35 years and over at recruitment, with demographic, anthropometric (BMI, waist circumference (WC)) and serum hormone (serum testosterone, estradiol (E2)) PSA and hematology assessments obtained over two waves was assessed. Men with a history of prostate cancer or missing PSA were excluded, leaving 970 men for the final analysis. Mixed-effects regressions and mediation analyses adjusting for hormonal and volumetric factors explore the potential mechanisms relating obesity to PSA. After adjusting for age, PSA levels were lower in men with greater WC (P = 0.001). In a multivariable model including WC, age, E2/testosterone and PlasV as predictors, no statistically significant associations were observed between with PSA and either WC (P = 0.36) or PlasV (P = 0.49), while strong associations were observed with both E2/testosterone (P < 0.001) and age (P < 0.001). In the mediation analyses with PlasV as the mediator, the average causal mediation effect (ACME) explained roughly 20% of the total effect of WC on PSA (P = 0.31), while when E2/testosterone is a mediator, the ACME explained roughly 50% of the effect (P < 0.001). Our findings indicate that lower PSA levels in obese men, as compared to normal weight men, can be explained both by hormonal changes (elevated E2/testosterone ratio) and hemodilution. Hormonal factors therefore represent a substantial but underappreciated mediating pathway.
Adel T Aref, Andrew D Vincent, Michael E O’Callaghan, Sean A Martin, Peter D Sutherland, Andrew J Hoy, Lisa M Butler and Gary A Wittert
Luke A Selth, Matthew J Roberts, Clement W K Chow, Villis R Marshall, Suhail A R Doi, Andrew D Vincent, Lisa M Butler, Martin F Lavin, Wayne D Tilley and Robert A Gardiner
Albert Beckers, Maya Beth Lodish, Giampaolo Trivellin, Liliya Rostomyan, Misu Lee, Fabio R Faucz, Bo Yuan, Catherine S Choong, Jean-Hubert Caberg, Elisa Verrua, Luciana Ansaneli Naves, Tim D Cheetham, Jacques Young, Philippe A Lysy, Patrick Petrossians, Andrew Cotterill, Nalini Samir Shah, Daniel Metzger, Emilie Castermans, Maria Rosaria Ambrosio, Chiara Villa, Natalia Strebkova, Nadia Mazerkina, Stéphan Gaillard, Gustavo Barcelos Barra, Luis Augusto Casulari, Sebastian J Neggers, Roberto Salvatori, Marie-Lise Jaffrain-Rea, Margaret Zacharin, Beatriz Lecumberri Santamaria, Sabina Zacharieva, Ee Mun Lim, Giovanna Mantovani, Maria Chaira Zatelli, Michael T Collins, Jean-François Bonneville, Martha Quezado, Prashant Chittiboina, Edward H Oldfield, Vincent Bours, Pengfei Liu, Wouter W de Herder, Natalia Pellegata, James R Lupski, Adrian F Daly and Constantine A Stratakis
X-linked acrogigantism (X-LAG) is a new syndrome of pituitary gigantism, caused by microduplications on chromosome Xq26.3, encompassing the gene GPR101, which is highly upregulated in pituitary tumors. We conducted this study to explore the clinical, radiological, and hormonal phenotype and responses to therapy in patients with X-LAG syndrome. The study included 18 patients (13 sporadic) with X-LAG and microduplication of chromosome Xq26.3. All sporadic cases had unique duplications and the inheritance pattern in two families was dominant, with all Xq26.3 duplication carriers being affected. Patients began to grow rapidly as early as 2–3 months of age (median 12 months). At diagnosis (median delay 27 months), patients had a median height and weight standard deviation scores (SDS) of >+3.9 SDS. Apart from the increased overall body size, the children had acromegalic symptoms including acral enlargement and facial coarsening. More than a third of cases had increased appetite. Patients had marked hypersecretion of GH/IGF1 and usually prolactin, due to a pituitary macroadenoma or hyperplasia. Primary neurosurgical control was achieved with extensive anterior pituitary resection, but postoperative hypopituitarism was frequent. Control with somatostatin analogs was not readily achieved despite moderate to high levels of expression of somatostatin receptor subtype-2 in tumor tissue. Postoperative use of adjuvant pegvisomant resulted in control of IGF1 in all five cases where it was employed. X-LAG is a new infant-onset gigantism syndrome that has a severe clinical phenotype leading to challenging disease management.