Endocrine Abstracts

JOINT1871

Introduction: ECS is a rare condition caused by excessive ACTH secretion from various tumors, with SCLC being the most common cause (20-30%). While ECS is reported in 1-6% of SCLC cases, recent data suggest it may be underestimated, reaching up to 25%. Patients with ECS at the course of SCLC are often not referred to endocrinologists. Severe hypercortisolemia in ECS leads to complications such as hypokalemia, worsening the prognosis.

Aim: This study reviews the clinical presentation, diagnostic methods, and treatment of ECS caused by SCLC, focusing on identifying a marker to aid diagnosis in non-endocrinology departments.

Materials and Methods: A retrospective analysis of 39 ECS cases (2000-2025) was performed, with 7 cases (18%) associated with SCLC. Diagnosis was based on clinical features, biochemical tests, imaging, and in some cases, ACTH detection in tumor samples.

Results: Seven patients (5 male, 2 female), aged 55-74 years (mean 65. 4), were analyzed. Initial symptoms included edema (4/7), muscle weakness (4/7), and resistant hypertension (1/7). All had significant weight loss (4-11 kg, mean 6. 6 kg). Muscle weakness was noted in 6/7, and bacterial infections in 5/7 (sepsis in 2). Typical Cushing’s symptoms were infrequent: central obesity (3/7), plethora (3/7), and striae (1/7), with no weight gain observed. Laboratory tests revealed hypokalemia in all patients, with potassium levels between 1. 14 and 2. 97 mEq/l (mean 2. 1), requiring high supplementation (up to 200 mEq/day) and spironolactone (6/7; 50-400 mg/d). The average time from first symptoms to ECS diagnosis was 1. 4 months. All patients were diagnosed in the metastatic stage. Serum cortisol levels ranged from 22. 7 to 192 μg/dL (mean 91. 7 μg/dL). Metyrapone (4 patients) reduced cortisol by 44% and modestly decreased potassium supplementation (mean 12. 2%). Osilodrostat (5 patients) reduced cortisol by 63. 4% and potassium supplementation needs by over 50% (mean 50. 1%). 5 patients died (mean survival 2. 5 months). In one case, cortisol therapy enabled chemoimmunotherapy, leading to survival over two years.

Discussion: The proportion of SCLC cases among ECS patients (18%) in our study was lower than in the literature, likely due to limited referrals to endocrinologists. Weight loss, common in cancer, and severe, refractory hypokalemia were the only symptoms, which occur in all patients. Early hypercortisolism treatment, particularly with osilodrostat, caused a significant reduction in potassium supplementation needs, highlighting its benefit. Persistent hypokalemia may serve as a key marker for ECS diagnosis in SCLC patients, who often do not present classic Cushing’s symptoms, especially in non-endocrinology wards.