Excess adiposity and iron-deficient status in Colombian women of reproductive age.

OBJECTIVE: Information about excess adiposity markers different from BMI and iron status is limited and more so about the shape of these associations. This study evaluated the relationship between three adiposity markers and iron-deficient status in reproductive-age women. METHODS: Cross-sectional analysis in 6357 non-pregnant women from the Colombian nutritional health survey (ENSIN) 2010. Exposures were the following: waist circumference (WC), waist-to-height ratio (W-HtR), BMI, and WC > 80 cm, W-HtR > 0.5, and BMI ≥ 25 and ≥30. Outcomes were the following: iron deficiency (ID) as serum ferritin <15 µg/L, ID as ferritin <30 µg/L, anemia, and continuous values of ferritin and hemoglobin. Logistic and linear regressions adjusted for sociodemographic/inflammation covariates were conducted. RESULTS: All the adiposity markers, continuous or categorical, were inversely and significantly associated with both ID thresholds in fully adjusted models (p < 0.05). W-HtR reported stronger effect estimates for ID (odds ratios < 0.5) and for prediction of log-ferritin levels (fully adjusted ß-coefficient [95% CI] 0.61 [0.39-0.82], p < 0.01) and was also inversely associated with anemia (p < 0.05). In cubic splines analyses, W-HtR, WC, and BMI were linearly associated with ID from values closer to international thresholds of general or central obesity, and the patterns of WC and BMI tended toward flatness. A significant decline in the likelihood of anemia was steeper by increasing W-HtR than by increasing BMI. After exclusion of women with C reactive protein > 5 mg/L or adjustment for C reactive protein, adiposity markers remained significantly related to ferritin levels and W-HtR with anemia. CONCLUSIONS: Women with higher adiposity were less likely to have an iron-deficient status. W-HtR was the strongest and most consistently associated marker. Inflammation would not be involved in the associations found.

Iron status and cardiometabolic risk in children.

AIM: We aimed to evaluate associations between serum ferritin and transferrin and variables related to the metabolic syndrome (MetS) in children. METHODS: Cross-sectional and longitudinal study in prepubertal children (n = 832) aged 3-14 years. A subset (n = 203) were re-examined after a mean follow-up of 3.7 ± 0.8 years[range 2-6]. Outcomes were MetS and MetS components scores, glycosylated haemoglobin (HbA1c), and their follow-up change. RESULTS: Children with low ferritin had increased HbA1c Z scores (ANCOVA, P = 0.003). Ferritin was inversely associated with glycaemia [fully adjusted ß (95% confidence interval): -2.35(-4.36 to -0.34)]. Transferrin was associated with diastolic blood pressure [ß: 0.02(0.01-0.04)] and log-HOMA-IR [ß:0.001(0.0005-0.002)]. MetS risk score worsened during follow-up in children with the lowest baseline ferritin levels. In contrast, at baseline ferritin was positively associated with all (except glycaemia) the MetS-related variables but adjustments for inflammatory, hepatic function, and body mass markers attenuated those associations (P > 0.05). CONCLUSIONS: Lower iron status was independently associated with glycaemic markers and MetS in children, whereas higher ferritin levels were related to other cardiometabolic risk markers under the influence of inflammation, hepatic injury and body mass. Research is required to study whether this mixed pattern is part of an early risk or would be explained by a normal transition during growth and development.

Serum ferritin and incident cardiometabolic diseases in Scottish adults.

BACKGROUND: Iron stores, estimated as ferritin levels, and type 2 diabetes (T2D) have been associated previously, while findings regarding coronary heart disease (CHD) and cerebrovascular disease (CEVD) are still inconclusive. No study has focused on simultaneous evaluation of associations between iron stores and the above cardiometabolic diseases (CMD) in the same population. We aim to evaluate the association between serum ferritin and risk of T2D, CHD and CEVD in Scottish population over a wide range of ferritin levels. METHODS: Longitudinal study in 6,497 participants of the 1995 and 1998 Scottish health surveys, who were followed-up until 2011. Cox regression models were conducted adjusting for age, sex/menopausal status, fibrinogen, GGT levels, smoking, alcohol consumption, total cholesterol, HDL-cholesterol, blood pressure, and BMI. Ferritin was used as continuous (sex/menopausal status-specific Z score) and categorical variable (sex/menopausal status-specific quartiles, quintiles and sextiles). RESULTS: During follow-up, 4.9% of the participants developed T2D, 5.3% CHD, and 2.3% CEVD. By using ferritin quartiles, serum ferritin was positively associated with T2D, CHD and CEVD but only the association with T2D remained after adjustment for covariates [Quartile 4 v. 1: adjusted HR 95% CI 1.59 (1.10-2.34); P = 0.006]. When ferritin sextiles were used (6 v. 1), the ferritin-CEVD association became slightly stronger and significant [adjusted HR 95% CI 2.08 (1.09-3.94); P = 0.024]. CONCLUSIONS: Iron stores relate differently to each CMD. Serum ferritin levels were positively and independently associated with incident T2D, and with incident CEVD if higher cut-off points for high ferritin levels were considered.

Soluble Transferrin Receptor, Antioxidant Status and Cardiometabolic Risk in Apparently Healthy Individuals.

Body iron excess appears to be related to insulin resistance and cardiometabolic risk and increased oxidative stress might be involved in this relationship. Very few studies have described the association between soluble transferrin receptor (sTfR) levels and cardiometabolic risk in the general population or antioxidant status. There were 239 subjects (20−65 years old) included in this cross-sectional study. Linear regressions adjusting for BMI, menopausal status, insulin resistance (HOMA-IR), physical inactivity, alcohol intake and subclinical/chronic inflammation were used to describe the association between sTfR, total antioxidant capacity (TAC), and measures of cardio-metabolic risk. sTfR levels were positively associated with TAC in men (ßeta [95% confidence interval ]: 0.31 [0.14 to 0.48]) and women (ßeta = 0.24 [0.07 to 0.40]) in non-adjusted and adjusted models (p < 0.05). In men, sTfR levels were inversely associated with waist circumference (ßeta [95% confidence interval]: −1.12 [−2.30 to −0.22]) and fasting glucose (−2.7 (−4.82 to −0.57), and positively with LDL cholesterol (12.41 (6.08 to 18.57) before and after adjustments for confounding variables. LDL cholesterol had a significant and positive association with TAC in non-adjusted and adjusted models in men (p < 0.05). sTfR levels are significantly associated with antioxidant status and a few specific cardio-metabolic risk variables, independently of covariates that included serum ferritin and hepcidin. This might imply that iron biomarkers in regard to cardiometabolic risk reflect physiological contexts other than iron metabolism.

Iron Status and Metabolically Unhealthy Obesity in Prepubertal Children.

OBJECTIVE: This study aimed to evaluate the association of metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) with iron status markers in prepubertal children. METHODS: Three hundred twelve prepubertal children with overweight and obesity from a pediatric general Spanish population were evaluated. MHO and MUO were defined as obesity with the absence or presence of metabolic syndrome components. Phenotypes of metabolically healthy overweight including obesity (MHOV) and metabolically unhealthy overweight including obesity (MUOV) were also studied and defined using the same criteria. Serum ferritin, transferrin, and blood hemoglobin levels were evaluated. RESULTS: Prevalence rates of MHOV and MHO were 35% (n = 111/312) and 27.1% (n = 42/155), respectively. Ferritin and hemoglobin levels were higher in children with MUOV versus MHOV (P < 0.05). MUO was positively associated with ferritin (beta [95% CI] = 0.43 [0.05 to 0.81]) and hemoglobin levels (0.43 [0.05 to 0.81]). These associations remained significant independently of age, sex, C-reactive protein, physical activity, and BMI/waist z scores in bivariate linear regression models. In multivariable models, transaminase levels attenuated the association of MUO with ferritin and hemoglobin levels (P > 0.05). CONCLUSIONS: MUOV and MUO are associated with higher ferritin and hemoglobin levels in prepubertal children affected by overweight and obesity. Increased circulating ferritin in MUO might be influenced by liver injury.