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Chronic kidney disease (CKD) with its associated comorbidities (e.g., diabetes, osteoporosis, cardiovascular disease), its complications (e.g., metabolic acidosis, inflammation) and its therapies (e.g., dialysis) all stimulate the loss of skeletal muscle mass.
Aging affects the neuromuscular system, reducing the muscular capacity to produce force and power and subsequently impairing the mobility, independence, and quality of life of elderly people.
The decline in strength and physical function is often more rapid than the concomitant loss of muscle mass in older adults. In HD patients we observed low physical function independently of muscle mass too. These findings suggest that muscle size alone cannot fully explain the loss of strength and physical function and that changes in muscle quality may play a role. Myosteatosis, the intramuscular infiltration of fat, has emerged as an important factor underpinning muscle quality.
Computed tomography (CT) is a well-accepted research method for assessing muscle size and volume, as well as muscle composition (quality).
The aim of our study was to evaluate the relationship between creatinine clearence (CrCl) and muscle composition by CT in patients aged 60 and older
We evaluated lower extremity function using a combination of gait speed and repeated chair rise time. Handgrip was used to measure strength. Body fat and water percentage were estimated using bioelectrical impedance analysis (BIA). A single slice CT scans at the right mid-thigh were obtained without contrast. Mean Hounsfield Unit (HU) and Cross-Sectional Areas of total area (CT-CSA-TA), normal density muscle area (CT-CSA-NDMA), low density muscle area (CT-CSA-LDMA) and very low-density muscle area (CT-CSA-VLDMA) through images were analyzed using Image J software. Fasting serum creatinine was used to calculate eGFR.
A total of 18 patients [73,3 (7) years, 78% male, estimated glomerular filtration rate (eGFR) 61.11(23) ml/min/1.73 m2] were recruited. eGFR below 60 ml/min/1.73 m2 was observed in 8 patients (CKDp), who did not present statistically significant differences in age, weight, height and waist circumference compared with patients with eGFR above 60 ml/min/1.73 m2 (NoCKDp). We also did not find significant differences in the evaluation of muscle power and strength between groups. By BIA fat percentage was similar but CKDp had greater water percentage than NoCKDp [52,1(4) vs 47,4(5) % p=0.019].
CT images showed less HU and greater CT-CSA-VLDMA in CKDp than NoCKDp [44,8(5) vs 49,3(7) HU p=0.05 and 15,42(10,3) vs 8,81(5,1) cm2 respectively], although muscle volume (CT-CSA-TA) did not show statistically significant differences between groups [203,98(116) vs 150,28(49) p=NS], Besides eGFR correlated positively with HU (CC 0,503 p<0.05) and negatively with CT-CSA-VLDMA (CC -0.614 p<0.015).
CKDp aged 60 and older showed equal muscle volume but more intramuscular fat infiltration than NoCKDp expressed by low HU and greater CT-CSA-VLDMA