Endocrine Abstracts

Background: Micronutrient deficiencies are an under-recognised complication in the long-term management of patients with gastroenteropancreatic neuroendocrine tumours (GEP-NETs). Despite plausible mechanisms for malabsorption, there is a limited real-world data on prevalence or evidence-based risk stratification to guide routine nutritional screening. We aimed to evaluate the prevalence of key micronutrient deficiencies and identify clinical predictors of deficiency in a specialist NET cohort.

Methods: We conducted a retrospective analysis of prospectively collected data from the South Wales NET service (2014-2024). Patients with confirmed GEP-NETs with at least one recorded serum micronutrient were included. Assessed parameters included vitamin B12, fat-soluble vitamins (A, D, and E), and trace elements (zinc, copper, selenium). Patients were stratified by steatorrhoea, somatostatin analogue (SSA) therapy, and prior ileal resection or right hemicolectomy. Multivariate logistic regression identified the independent predictors of deficiency.

Results: Among 342 patients (53% male, median age 67.5), midgut NETs were the most common (51%), with 60% low grade, and 53% metastatic at diagnosis. Ileal resection or right hemicolectomy was documented in 54.2%, and 53% received SSA. Steatorrhoea was present in 101 patients.

Deficiency rates (amongst those tested) were:

• Vitamin B12: 42.5%

• Fat-soluble vitamins (A, D, E): 46.4%

• Trace elements (Zn, Cu, Se): 30.4%

Multivariate analysis identified steatorrhoea as an independent predictor of fat-soluble vitamin deficiency (OR=2.14; 95% CI=1.07-4.27; P = 0.032). Steatorrhoea itself was strongly associated with SSA use (OR=6.98; P < 0.001) and ileal resection/right hemicolectomy (OR=5.11; P < 0.001). Ileal resection/right hemicolectomy was also independently associated with B12 deficiency (OR=1.74; 95%CI 1.05-290; P = 0.033).

Conclusion: In one of the largest single-centre NET cohorts globally, we demonstrate a high prevalence of micronutrient deficiencies. Simple clinical indicators, such as steatorrhoea and prior ileal resection, may offer more robust risk prediction than SSA exposure alone. These findings support a shift towards targeted micronutrient screening protocols to personalise nutritional monitoring, and improve long-term care in GEP-NETs.

Key words: Neuroendocrine tumours, micronutrients, nutrition, steatorrhoea, somatostatin analogues, ileal resection.