PET‐CT using 18F‐FDG is employed for detecting brown adipose tissue (BAT) in humans. Alternative methods are needed because of the radiation and cost of PET‐CT imaging. The aim was to evaluate the accuracy of infrared thermography (IRT) in detecting human BAT benchmarked to PET‐CT imaging. Seventeen individuals underwent a total of 29 PET‐CT scans, 12 of whom were studied twice, after 2 h of cold stimulation at 19°C, in parallel with measurement of skin temperatures overlying the supraclavicular (SCV) fossa and the lateral upper chest (control), before and after cold stimulation. Of the 29 scans, 20 were BAT positive after cold stimulation. The mean left SCV temperature tended to be higher in the BAT‐positive group before and during cooling. It was significantly higher (P =0.04) than the temperature of the control area, which fell significantly during cooling in the BAT‐positive (−1.2 ± 0.3°C, P =0.002) but not in the negative (−0.2 ± 0.4°C) group. The temperature difference (Δtemp) between left SCV and chest increased during cooling in the BAT‐positive (1.2 ± 0.2 to 2.0 ± 0.3°C, P <0.002) but not in the negative group (0.6 ± 0.1 to 0.7 ± 0.1°C). A Δtemp of 0.9°C conferred a positive predictive value of 85% for SCV BAT, superior to that of SCV temperature. The findings were similar on the right. In conclusion, the Δtemp is significantly and consistently greater in BAT‐positive subjects. The Δtemp quantified by IRT after 2‐h cooling shows promise as a noninvasive convenient technique for studying SCV BAT function.

Prolonged exposure to glucocorticoid suppresses the function of human BAT. The enhancement of energy production and lipogenesis in the face of reduced dissipation of energy as heat suggests that glucocorticoids channel energy towards fat storage after nutrient intake. This is a novel mechanism of glucocorticoid-induced obesity.

MC antagonism enhanced human BAT function in response to cooling and to a meal during which lipid synthesis was suppressed. As postprandial EPR comprises energy dissipated as heat and energy required to store nutrients, the reduction in lipid synthesis during MC antagonism is a probable consequence of concurrent stimulation of BAT thermogenesis. The shift in energy usage from storage to heat dissipation indicates that MC antagonists may have therapeutic benefit for obesity.

Background In primary aldosteronism (PA), excessive, autonomous secretion of aldosterone is not suppressed by salt loading or fludrocortisone. For seated saline suppression testing (SSST), the recommended diagnostic cutoff 4-hour plasma aldosterone concentration (PAC) measured by high-performance liquid chromatography–mass spectrometry (HPLC-MS/MS is 162 pmol/L. Most diagnostic laboratories, however, use immunoassays to measure PAC. The cutoff for SSST using immunoassay is not known. We hypothesized that the cutoff is different between the assays. Methods We analyzed 80 of the 87 SSST tests that were performed during our recent study defining the HPLC-MS/MS cutoff. PA was confirmed in 65 by positive fludrocortisone suppression testing (FST) and/or lateralization on adrenal venous sampling and excluded in 15 by negative FST. PAC was measured by a chemiluminescence immunoassay (PACIA) in the SSST samples using the DiaSorin Liaison XL analyzer, and receiver operating characteristics (ROC) analysis was performed to identify the PACIA cutoff. Results ROC revealed good performance (area under the curve = 0.893; P &lt; .001) of 4-hour postsaline PACIA for diagnosis of PA and an optimal diagnostic cutoff of 171 pmol/L, with sensitivity and specificity of 95.4% and 80.0%, respectively. A higher cutoff of 217 pmol/L improved specificity (86.7%) with lower sensitivity (86.2%). PACIA measurements strongly correlated with PAC measured by HPLC-MS (r = 0.94, P &lt; .001). Conclusions A higher diagnostic cutoff for SSST should be employed when PAC is measured by immunoassay rather than HPLC-MS/MS. The results suggest that (i) PA can be excluded if 4-hour PACIA is less than 171 pmol/L, and (ii) PA is highly likely if the PACIA is greater than 217 pmol/L by chemiluminescence immunoassay. A gray zone exists between the cutoffs of 171 and 217 pmol/L, likely reflecting a lower specificity of immunoassay.

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Context and Objective Posture-responsive and -unresponsive aldosterone-producing adenomas (APAs) account for approximately 40% and 60% of APAs, respectively. Somatic gene mutations have been recently reported to exist in approximately 90% of APAs. This study was designed to characterize the biochemical, histopathologic, and genetic properties of these two types of APA. Methods Plasma levels of aldosterone and hybrid steroids (18-oxocortisol and 18-hydroxycortisol) were measured by LC-MS/MS. Immunohistochemistry (IHC) for CYP11B2 (aldosterone synthase) and CYP17A1 (17α-hydroxylase) and DNA sequencing (Sanger and next-generation sequencing) were performed on APA tissue collected from 23 posture-unresponsive and 17 posture-responsive APA patients. Results Patients with posture-unresponsive APA displayed higher (P &lt; 0.01) levels of hybrid steroids, recumbent aldosterone and cortisol, larger (P &lt; 0.01) zona fasciculata (ZF)-like tumors with higher (P &lt; 0.01) expression of CYP17A1 (but not of CYP11B2) than patients with posture-responsive APA (most of which were not ZF-like). Of 40 studied APAs, 37 (92.5%) were found to harbour aldosterone-driving somatic mutations (KCNJ5 = 14, 35.0%; CACNA1D = 13, 32.5%; ATP1A1 = 8, 20.0%; and ATP2B3 = 2, 5.0%), including 5 previously unreported mutations (3 in CACNA1D and 2 in ATP1A1). Notably, 64.7% (11/17) of posture-responsive APAs carried CACNA1D mutations, whereas 56.5% (13/23) of posture-unresponsive APAs harboured KCNJ5 mutations. Conclusions The elevated production of hybrid steroids by posture-unresponsive APAs may relate to their ZF-like tumor cell composition, resulting in expression of CYP17A1 (in addition to somatic gene mutation-driven CYP11B2 expression), thereby allowing production of cortisol which acts as the substrate for CYP11B2-generated hybrid steroids.

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