Assessment of plasma dexamethasone levels after 1-mg dexamethasone suppression test in adults with obesity

BACKGROUND

The 1-mg overnight dexamethasone suppression test is the most frequently used screening test for Cushing's syndrome. It has been proposed that people with obesity may have insufficient plasma dexamethasone levels for the test which may result in false positives. We sought to compare the plasma dexamethasone levels after 1-mg dexamethasone suppression test in healthy obese participants and in optimal-weight participants.

METHODS

A total of 30 optimal-weight participants (BMI ≤ 25 kg/m2 ) and 62 obese participants (BMI > 25 kg/m2 ) were enroled in the study. Obese participants were further divided into class 1 (25-29.9 kg/m2 ) and class 2 (>30 kg/m2 ). After a standard overnight 1-mg dexamethasone suppression test, blood samples were obtained for serum cortisol and plasma dexamethasone levels. Plasma dexamethasone levels were quantified using liquid chromatography - mass spectrometry (LC-MS/MS).

RESULTS

No significant difference in plasma dexamethasone levels were found between obese and optimal-weight participants (3.31 ± 1.35 vs. 2.82 ± 1.11 nmol/L, mean ± SD; p = .09 respectively). There were also no correlations found between sex, BMI, body surface area and plasma dexamethasone levels. There was also no significant difference in the proportion of participants who achieved a plasma dexamethasone level >3.3 nmol/L in comparison between obesity class 1, obesity class 2, and optimal-weight groups.

CONCLUSION

Our results suggest that obesity does not affect plasma dexamethasone levels. However, dexamethasone measurement may still be helpful in patients who are being investigated for Cushing's syndrome and suspected to have a false-positive DST.

Association of osteoporosis and sarcopenia with fracture risk in transfusion-dependent thalassemia

Patients with transfusion-dependent thalassemia (TDT) have an increased risk of osteoporosis and fractures. They also have several potential factors associated with sarcopenia. There has been currently no study on sarcopenia and its association with falls and fractures in TDT. This study aims to determine the prevalence of and factors associated with osteoporosis, fragility fractures, and sarcopenia in adults with TDT. A cross-sectional study was conducted at the hematologic clinic at King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Clinical data and laboratory testing were collected. Bone mineral density and morphometric vertebral fracture were assessed. Sarcopenia was defined using the 2014 and 2019 Asian Working Group for Sarcopenia (AWGS) criteria. We included 112 TDT patients aged 35.1 ± 12.5 years. The prevalence of osteoporosis was 38.4%. Fragility fractures were found in 20.5% of patients. Lower BMI (OR 0.29; 95% CI 0.12-0.72, P = 0.007) and hypogonadal state (OR 3.72; 95% CI 1.09-12.74, P = 0.036) were independently associated with osteoporosis. According to the 2014 AWGS criteria, the prevalence of overall sarcopenia and severe sarcopenia was 44.6% and 13.4%, respectively. Severe sarcopenia was strongly associated with fragility fractures (OR 4.59, 95% CI 1.21-17.46, P = 0.025). In conclusion, osteoporosis, fragility fractures, and sarcopenia were prevalent in adults with TDT. Severe sarcopenia was associated with fragility fractures. Early osteoporosis and sarcopenia screening and prevention may reduce fracture risk and its complications in these patients.