Introduction: In healthy, obese and diabetic women of different ages marrow adipose tissue (MAT) is closely associated with subcutaneous (SAT) and visceral (VAT) adipose tissue volumes^1-3. However, the relationship between MAT and SAT/VAT in men and particularly older men - that naturally undergo significant fat redistribution⁴ - is not very well known. Therefore, using a non-invasive imaging technique we investigated the associations of fat depots in older men; and hypothesised that MAT volume is independent of SAT/VAT, weight and body mass index (BMI).

 Methods: Cross-sectional study included 120 healthy men (age: 67.7±6). Assessments included: anthropometric parameters (e.g. weight, BMI, waist circumference, etc.); computed tomography (CT) at L2 to L4 and hip level; full serum biochemistry panel [including: calcitropic hormones, bone-active hormones and biomarkers (PTH & Vitamin D, osteopontin, OPG, RANKL, CTX, P1NP), glucose, insulin, lipid profiles (LDL, HDL, Cholesterol, TG), leptin, resistin and adiponectin, selected cytokines and growth factors (IL1α & β, IL6, TNF α, IFNγ, MIP1α, IGF1), CRP and etc.].

 Using CT images, MAT within L2 and L3 vertebra and left and right hip marrows [neck and trochanteric regions of interest (ROIs)] was quantified. VAT and SAT were calculated at the level of L2 and L4. Image analyses were carried out using Slice-O-Matic^® software⁵.

 Results: Although MAT increased at the expense of bone volume in all regions of interest (R=-0.80 to -0.95, p<0.001), MAT volume in all regions of interest was independent of weight, BMI, VAT and SAT volumes.

 Conclusion: The lack of association between MAT and other types of fat in the older men provides further evidence on the different behaviour and metabolic profile of MAT⁶ vs SAT/VAT. Further studies in younger men are warranted to explore whether this phenomenon applies to all men; or whether fat redistribution later in life causes this lack of association.