High Serum Adiponectin Level Is a Risk Factor for Anemia in Japanese Men: A Prospective Observational Study of 1,029 Japanese Subjects

A direct effect of the hematocrit on blood glucose: Evidence from hypoxia- and erythropoietin-treated mice

Blood glucose is lower in mountain dwellers living under low partial oxygen pressure. We show that obese mice maintained under hypoxia exhibit a delayed but distinct decrease in blood glucose with improved insulin sensitivity, which is independent of changes in body weight. This effect of hypoxia is mediated by erythropoiesis and is a direct result of the rising hematocrit, which could be due to erythrocytes acting as carriers of glucose units in the blood. Glucose lowering by the red cell mass is evidenced by a prompt decrease in glycemia in mice receiving a blood transfusion. Furthermore, life under hypoxia as well as treatment with erythropoietin reduce glycemia also in mice expressing the erythropoietin receptor exclusively in hematopoietic cells, which contrasts with previous assumptions attributing metabolic actions of erythropoietin to direct action on nonhematopoietic tissues. Our results provide a rationale for associations between hematocrit and blood glucose in humans under anti-anemic therapy, polycythemia, smoking, and high-altitude exposure.

Association of anemia with hyperadiponectinemia in oldest-old Japanese women who resided at home alone without wheelchair use

The association of anemia with hyperadiponectinemia (HAN) (≥ 20 μg/mL) was studied in 95 Japanese women aged 65-74 (young-old), 175 women aged 75-84 (old-old), and 51 women aged over 85 (oldest-old) who resided at home alone without wheelchair use. The prevalence of anemia was 21.5% overall and increased with aging stepwise (9.5, 22.9, and 39.2% in young-olds, old-olds, and oldest-olds, respectively, p < 0.001). Most of the anemia was normocytic and only one woman had hemoglobin < 10 g/dL. Old-olds with anemia had low serum iron, albumin, and cholesterol and a higher prevalence of renal insufficiency (30.0 versus 5.2%, p < 0.001). In contrast, these variables did not differ between anemic and non-anemic young-olds. oldest-olds with anemia had low serum iron and higher adiponectin concentrations (22.8 ± 9.8 vs. 16.0 ± 6.7 μg/mL, p = 0.005) and prevalence of HAN (60.0 vs. 19.4%, p = 0.006) and renal insufficiency (50.0 vs. 0%, p < 0.001). However, inflammatory markers did not differ between anemic and non-anemic oldest-olds. The prevalence of anemia was higher in oldest-olds with versus without HAN (66.7 vs. 24.2%, p = 0.006). In multivariable logistic regression analysis, anemia was associated with HAN (OR: 15.7, 95% CI 1.2-207, p = 0.03) in oldest-olds and with renal insufficiency (OR: 7.1, 95% CI 2.4-21.0, p < 0.001) in old-olds. In conclusion, the association of anemia with HAN was evident in oldest-old Japanese women, suggesting the anti-inflammatory properties of circulating adiponectin.

New Insights into Adiponectin and Leptin Roles in Chronic Kidney Disease

Chronic kidney disease (CKD) is commonly associated with a high burden of comorbidities and poor clinical outcomes. Malnutrition–inflammation–atherosclerosis syndrome is common in the more severe stages of CKD, suggesting a close interplay for these three comorbid conditions. Both malnutrition and obesity are associated with a disturbed adipokine profile and inflammation, contributing to a higher risk of cardiovascular disease (CVD) events. Adiponectin and leptin have important roles in carbohydrate and lipid metabolism, and in the inflammatory process. The effects of adiponectin and leptin alterations in CKD, which are usually increased, and their association with the different comorbidities found in CKD, will be focused on to understand their crosstalk with the risk of CVD events. Nonetheless, although adiponectin and leptin contribute to a higher risk of CVD events, further studies are warranted to fully clarify their roles, especially when different comorbidities exist.

Association of Age and Anemia With Adiponectin Serum Levels in Normal-Weight Japanese Women

BACKGROUND

Adiponectin serum levels are affected by sex, ethnicities, adiposity, age and several pathological conditions such as anemia. The prevalence of hyperadiponectinemia (≥ 20 mg/L) in relation to anemia (hemoglobin < 12 g/dL) was examined in normal-weight Japanese women.

METHODS

Serum adiponectin and blood hemoglobin were measured in 311 young women aged 18 - 24 years (A), 148 of their middle-aged mothers aged 39 - 60 years (B) and 322 community-dwelling women aged ≥ 65 years (C) with a mean body mass index (BMI) of 20.4, 22.0 and 22.4 kg/m2, respectively. Elderly women were subdivided into three age groups: between 65 and 74 years (n = 95, X), between 75 and 84 years (n = 176, Y) and older than 85 years (n = 51, Z).

RESULTS

The prevalence of hyperadiponectinemia (A: 3.9%, B: 3.4%, C: 22.7%, P < 0.001) was low and serum adiponectin (A: 11.5 ± 4.3 mg/L, B: 11.8 ± 4.9 mg/L, C: 15.3 ± 7.8 mg/L, P < 0.001) did not change until middle-aged but increased thereafter in a stepwise fashion (X: 18.9%, Y: 22.7%, Z: 35.3%, P = 0.07 and X: 13.9 ± 6.9 mg/L, Y: 15.1 ± 7.7 mg/L, Z: 18.7 ± 8.6 mg/L, P = 0.001, respectively). There were inverse associations of adiponectin with age (r = -0.201, P < 0.001) and hemoglobin (r = -0.318, P < 0.001) in elderly women but not even in young and middle-aged women combined. Furthermore, anemia was associated with higher prevalence of hyperadiponectinemia (34.8% vs. 20.6%, P = 0.01) and higher serum adiponectin (18.3 ± 9.4 mg/L vs. 14.5 ± 7.1 mg/L, P < 0.001) in elderly women but not in younger and middle-aged women.

CONCLUSIONS

In normal-weight Japanese women, the prevalence of hyperadiponectinemia and serum adiponectin were increased and associated with anemia at 65 years of age and older.

High serum adiponectin is associated with anemia development in chronic kidney disease: The results from the KNOW-CKD study

BACKGROUND

Adiponectin is an adipokine secreted by adipocytes. A low adiponectin level is a significant risk factor of diabetes mellitus and cardiovascular disease. Recent studies have shown that adiponectin is negatively associated with hematopoiesis and predicts the development of anemia in the general population. In chronic kidney disease (CKD) patients, circulating adiponectin level is paradoxically elevated and the role of adiponectin is complex. Therefore, we evaluated the relationship between adiponectin and anemia in these patients.

METHODS

This prospective longitudinal study included 2113 patients from the KNOW-CKD study (KoreaN cohort study for Outcome in patients With CKD), after excluding 125 without data on adiponectin levels. Hemoglobin levels were measured yearly during a mean follow-up period of 23.7 months. Anemia was defined as hemoglobin levels of <13.0 and 12.0 g/dL for men and women, respectively.

RESULTS

Mean patient age was 53.6 ± 12.2 years, and 1289 (61%) were men. The mean estimated glomerular filtration rate (eGFR) was 50.4 ± 30.2 mL min^-1 1.73 m^-2. Serum adiponectin level was inversely associated with body mass index, eGFR, log-transformed C-reactive protein, and positively with Charlson comorbidity index, urine protein to creatinine ratio, and high density lipoprotein cholesterol. In addition, serum adiponectin level was also negatively correlated with hemoglobin level and reticulocyte production index in both men and women. In multivariable linear regression analysis after adjustment of multiple confounders, adiponectin was negatively associated with hemoglobin (men, β = -0.219, P < .001; women, β = -0.09, P = .025). Among 1227 patients without anemia at baseline, 307 newly developed anemia during the follow-up period. In multivariable Cox regression analysis after adjustment of confounders, high adiponectin level was significantly associated with an increased risk of incident anemia (per 1 µg/mL increase, hazard ratio, 1.02; 95% confidence interval 1.01-1.04; P = .001).

CONCLUSIONS

A high serum adiponectin level is independently associated with a low hemoglobin level and predicts the development of anemia in patients with CKD. These findings reveal the potential role of adiponectin in CKD-related anemia.

Association of adiposity with hemoglobin levels in patients with chronic kidney disease not on dialysis

Background

In the general population, adiposity influences erythropoiesis and iron metabolism. We aimed to assess the relationships between adiposity [estimated by body mass index (BMI) and abdominal circumference (AC)] and biomarkers of erythropoiesis in patients with chronic kidney disease (CKD) not on dialysis.

Methods

A total of 2322 patients from the Chronic Kidney Disease Japan Cohort study were included. Patients were grouped according to BMI (low: < 18.5 kg/m², normal: 18.5–24.5 kg/m², and high: ≥ 25 kg/m²) and AC categories (large: ≥ 90 cm for men and ≥ 80 cm for women; small: < 90 cm and < 80 cm, respectively). Body composition and laboratory data were assessed at baseline, and at 1 and 2 years of follow-up.

Results

Multivariate regression analysis of the 3 time-points showed that high BMI and large AC in male patients were significantly associated with higher hemoglobin levels. Hemoglobin levels were lower in female patients with low BMI and small AC than that in female patients with normal BMI and large AC, respectively; however, hemoglobin levels plateaued above a threshold of 25 kg/m² for BMI and 80 cm for AC. While BMI and AC were positively associated with C-reactive protein levels, they were not associated with levels of transferrin saturation, ferritin, and erythropoietin in multivariate models.

Conclusions

Body composition appears to be associated with erythropoiesis; however, adiposity may be only associated with increased erythropoiesis in male patients. In addition, body composition does not appear to hamper iron metabolism in CKD patients not on dialysis.

Electronic supplementary material

The online version of this article (10.1007/s10157-017-1501-y) contains supplementary material, which is available to authorized users.