The article was originally titled "Measuring Sarcopenia in People Living with HIV" by Kirk Taylor
At the 14th International Symposium on HIV and Ageing, Dr. Peggy Cawthon presented a method for measuring sarcopenia in HIV patients.
Sarcopenia in people living with HIV is characterized by a gradual and generalized decline in skeletal muscle strength and quality, as well as impaired physical performance, and is a marker of premature aging, with adverse consequences including physical disability, poor quality of life, and increased risk of death. This can happen even with regular exercise.
This disease may be related to factors such as mitochondrial damage to the cells of infected patients, chronic inflammation, metabolic abnormalities and increased adipose tissue caused by drugs such as TAF, Kritze, Zidovudine, etc., and low levels of male hormones.
In addition, sarcopenia is associated with severe reductions in muscle size, strength, and function, and there is currently no uniform standard for the diagnosis of sarcopenia.
There are many ways to measure muscle mass, including DEXA (dual-energy x-ray absorptiometry), bioimpedance analysis (BIA), CT scans, and D3-creatinine dilution. Muscle function or strength can also be assessed by grip strength, walking speed, and self-reported disability or limitation. Grip strength is often used as a hallmark of these methods because the test is less expensive and takes less time, whereas lower extremity testing can be more subjective and limited in older people.
The DEXA scan not only measures bone mineral density (BMD) and fat mass, but also indirectly estimates muscle mass. Dividing the dexa value of the limbs (legs and arms only) by height can be used as a method for the risk of sarcopenia. Sarcopenia is defined as a man who is less than 726 kg m or less than 5 for women45 kg/m²。
The meta-analyses in the review did not show a strong** link between muscle mass and function as inferred by DEXA. Studies have also shown that people with osteoarthritis or diabetes are able to maintain strength despite weight loss. In addition, DEXA is a highly subjective measurement method that is prone to measurement errors.
The method of direct measurement of muscle mass can be calculated by measuring urine creatinine, since 98% of creatine is stored in muscle tissue and its level is stable, so it is directly proportional to muscle mass.
The D3-creatinine dilution test is used to determine total muscle mass. In short, 30 mg of labeled creatine is taken orally, which is converted to creatinine and reaches a stable level within three to six days. The ratio of D3-creatinine to creatinine in urine is used to calculate muscle mass. The higher the d3-creatinine ratio, the lower the muscle mass.
In the MROS study of 1400 men, there was a correlation in muscle mass measured by DEXA or D3-creatinine (r = 0.).66), but DEXA overestimates muscle mass. People with lower grip strength and walking speed also have lower muscle mass as calculated by the D3-creatine method. Similar results were observed in the SOMMA study of 875 women older than 75 years.
There is currently no uniform measurement of sarcopenia in people living with HIV, including older adults. The current approach proposes to collect multiple components covering muscle function, size, physical performance, self-reported disability, and health status.