This year, two new consensus conferences on the diagnosis and management of sarcopenia
have been published.1, 2 Both confirm the need to screen for sarcopenia in older persons.
Suggested screening approaches are the SARC‐F,3, 4 the Ishii screening test,5, 6 or
grip strength. It should be recognized that grip strength was suggested for screening
by one consensus group1 and as part of the diagnosis by the other.2 Measuring mid‐calf
muscle circumference improves the sensitivity and specificity of the SARC‐F when it
is compared with the consensus definitions.7, 8, 9
A number of consensus definitions for sarcopenia have been developed.2, 11, 12, 13
All require either functional impairment (slow walking speed) or grip strength together
with a low muscle mass. While the persons diagnosed by any of these definitions overlap,
they all have different sensitivity and specificity when compared with one another
or functional outcomes due to the different cut‐off points.14, 15 The Asian Group
made it clear that cut‐offs are very different for persons with Asian ethnicity compared
with Europeans.13 [These definitions have led to the International Classification
of Disease (10th edition) to recognize sarcopenia as an independent condition (M62.84)].16,
17
There are a number of different methods available to measure lean body mass including
air displacement plethysmography, bioelectrical impedance analyses, dual‐energy X‐ray
absorptiometry, and ultrasound.18, 19, 20, 21 Each of these methods has been demonstrated
to have problems in accurately determining muscle mass.22 Recently, D3‐creatine dilution
has been demonstrated to be more accurate in measuring muscle mass23 and more strongly
related to physical performance.22
While age‐related sarcopenia is considered to be primary sarcopenia, a number of disease
states, for example, diabetes mellitus,24, 25 male hypogonadism,26, 27 and chronic
obstructive pulmonary disease28 can produce secondary sarcopenia. Cachexia is a complex
metabolism disorder leading to anorexia, muscle wasting, and loss of fat.29 The Glasgow
Prognostic Score (low serum albumin and elevated C‐reactive protein) can be used to
distinguish secondary sarcopenia from cachexia.30
The advent of patient‐centred (P4) care has increased attention to the fact that different
molecular changes can result in the need to have different therapeutic approaches
to similar conditions such as sarcopenia31, 32 (Table 1). In this issue of the journal,
Riuzzi et al.33 highlight that sarcopenia can result from a variety of molecular changes
resulting in changes in myofibre metabolism and alterations in satellite cell properties.
Abnormalities in these pathways can be due to insulin growth factor‐1/insulin receptors,
activin (myostatin) receptors, tropomysin receptor, kinase C receptors (neurotrophin
and G‐protein receptors), a variety of cytokines, and testosterone through activation
of β‐catenin.34, 35, 36, 37, 38 Thus, in the long run, the ideal treatment of sarcopenia
will involve identification of the aberrant molecular pathway and the possible hormone
causing this imbalance.
Table 1
Patient‐centred approach to management of sarcopenia
Early identification
Primary prevention
Secondary prevention
Tertiary prevention
SARC‐F or ISHII screening test
Exercise
Resistance exercise
Physical therapy
Adequate protein diet
Low‐protein diet: leucine‐enriched essential amino acids or methyl hydroxy butyrate
supplementation
Occupational therapy
In ALL hospitalized: aggressive resistance exercise (include intensive care unit)
Male hypogonadism: testosterone
If dysphagia: speech therapy
If falling: use CDC STEADI or F3ALLS approach
Provide adequate protein intake
If low 25(OH) vitamin D—1000 IU vitamin D
Optimal treatment of COPD; CHF and diabetes mellitus
Exclude cachexia: elevated CRP + low protein
Exclude protein energy malnutrition (anorexia or malabsorption)
‐Look for treatable causes
‐Caloric supplement
‐Future: anamorelin
Future: antibodies to myostatin
At present, the treatment of sarcopenia is focused on resistance exercise.1 The use
of leucine essential amino acids and/or β‐hydroxybutyrate has not been clearly established
but would seem a reasonable adjunct in persons with low protein intake.39, 40, 41,
42, 43, 44, 45 Drugs that have potential to treat sarcopenia include testosterone
and anabolic steroids,46, 47, 48 myostatin antibodies,49, 50 activin receptor antibodies,51
and the ghrelin agonist, anamorelin.52 There is also interest in the role of beta‐blockade,53
some angiotensin‐converting enzyme inhibitors,54 and sarconeos, which activates the
MAS (angiotensin‐1) receptor.55 A recent study suggested that metformin may improve
mobility in persons with diabetes mellitus.56 Still highly experimental but likely
to play a role in the future management of sarcopenia are CRISPR techniques57 and
possibly stem cell therapy.58
Sarcopenia is a major cause of physical frailty59, 60, 61 and falls62, 63 in older
persons. As at present, there is a simple therapy—aggressive resistance exercise—when
sarcopenia is detected early, it seems reasonable to screen older persons and those
with diabetes for sarcopenia and frailty using the Rapid Geriatric Assessment tool64,
65, 66, 67 and begin secondary prevention as early as possible. The SarQOL can be
utilized to measure an improvement of health‐related quality of life in these persons.68
A recent study demonstrated that an intense level of physical exercise in hospital
patients can prevent the muscle and functional loss that occurs in hospitalized patients.69
Conflict of interest
None declared.