Endocrine Abstracts

Background and objectives: Obesity is associated with a relatively high prevalence of anaemia and iron deficiency compared to normal weight individuals; the cause is unknown. We aimed to determine the prevalence of iron deficiency and anaemia in a severely obese cohort of bariatric surgery candidates, and to explore underlying associations with markers of nutrition and inflammation.

Methods: In a retrospective review of 703 consecutive patients presenting for bariatric surgery assessment, 656 were evaluated after exclusions for haemoglobinopathy and missing data. Assessment included; clinical history, basic anthropometry, and blood tests (haemoglobin (Hb), serum iron, total iron binding capacity, iron binding saturation, ferritin, vitamin B₁, vitamin B₁₂, folate, white cell count (WCC), and C-reactive protein (CRP)). Anaemia was defined as; men: Hb<13 g/dl, or women: Hb<12 g/dl; and iron deficiency as an abnormality in two or more measures of iron status. Indirect measures of adiposity included BMI and percentage body fat (BF%) estimated from the CUN-BAE equation. Statistical analyses: stepwise regression was performed with independent predictors of serum iron concentration: age, gender, BMI, BF%, index of multiple deprivation, diabetes status, number of comorbidities, WCC, CRP, folate, vitamin B₁₂, and use of multivitamins, metformin, insulin, non-steroidal anti-inflammatory drugs (NSAIDs) or proton pump inhibitors.

Results: Anaemia and iron deficiency were present in 9.9 and 11.4% of patients, respectively. Stepwise regression revealed an association between serum iron concentration and CRP (R²=0.227; P=0.001), however CRP concentrations were only available for 156 patients (24%). Excluding CRP from analyses, WCC had the largest effect on serum iron concentration, with NSAIDs, gender, and diabetes status also contributing (R²=0.076; P<0.001), albeit leading to a much weaker association than observed with CRP.

Conclusion: Anaemia and iron deficiency are relatively common in severely obese individuals, potentially due to inflammation causing deranged iron homeostasis, although a multifactorial aetiology is likely.