Features of rheumatoid cachexia:
(1) muscle wasting
(2) loss of visceral non-fat cell mass
(3) impaired immunity
(4) muscle weakness
(5) decreased functional capacity with disability
(6) elevated resting energy expenditure
(7) increased protein catabolism
(8) variable accumulation of tissue fat with central obesity
(9) low serum albumin
Factors associated with rheumatoid cachexia:
(1) increased inflammatory cytokines (tumor necrosis factor, interleukin-1 beta)
(2) increased disease activity (and number of swollen joints)
Rheumatoid cachexia may be present even when the disease appears to be clinically well-controlled.
Diagnosis:
(1) Weight loss and loss of appetite are uncommon.
(2) The body mass index can easily miss the cachexia because of increased body fat. The fat-free body mass is a more reliable measure.
(3) Clinical anthropmetrical measurements can be insensitive.
(4) The Mini Nutritional Assessment (MNA) has a sensitivity of 85% but is relatively nonspecific (39%).
(5) Accurate diagnosis requires determination of body composition. Dual energy X-ray absorptiometry (DXA) may be the most specific method. Bioelectrical impedance analysis (BIA) may be good for monitoring changes in body composition.
