Table 3.
Analytical aspects for the use of biochemical markers for the conduct of pharmacological trial in sarcopenia
| Type of assay | Matrix | Automatization | Widely available |
Preanalytical constrains* | Biological variation | Limitations | |
|---|---|---|---|---|---|---|---|
| Assessment of musculoskeletal status | |||||||
| Muscle mass | |||||||
| D3creatine dilution test | LC–MS/MS | Urine | None | No | Fasting for morning urine | Unknown | Need a correction based on creatinine |
| Myokines | |||||||
| Myostatin | LC–MS/MS | Serum | None | Yes | 24 h exercise-free period | Sex dependent | |
| ELISA | Plasma | Uncertainties about age-dependent levels | ELISA specificity is controversial | ||||
| Follistatin | ELISA |
Serum Plasma |
None | Yes | 24 h exercise-free period | Sex dependent | |
| Activin A | ELISA |
Serum Plasma |
None | Yes | 24 h exercise-free period | Uncertainties about age and sex-dependent levels | |
| GDF-15 | ELISA |
Serum Plasma |
None | Yes | 24 h exercise-free period | Age dependent | |
| Irisin | ELISA |
Serum Plasma |
None | Yes | Unknown | Unknown | |
| Neuro-muscular junction | |||||||
| CAF | ELISA | Serum | None | No | Unknown | Uncertainties about sex-dependent levels | Kits unavailable |
| BDNF | ELISA |
Serum Plasma |
None | Yes | 24 h exercise-free period | Age and sex dependent | |
| Others | |||||||
| PIIINP |
RIA ELISA ECLIA |
Serum | Only with ECLIA | Yes | Fasting | Unknown | High variabilities between techniques |
| Sarcopenia index |
Colorimetric Enzymatic Turbidimetric |
Serum Plasma |
Yes | Yes | No preanalytical constrains | Based on data for creatinine and cystatin | Only the non eGFR based formula is recommended |
| Assessment of causal factors | |||||||
| Adipokines | |||||||
| Adiponectin |
ELISA ECLIA |
Serum Plasma |
Only with ECLIA | Yes | Fasting | Age, BMI and sex dependent | |
| BV described | |||||||
| Leptin | ELISA |
Serum Plasma |
None | Yes | Fasting | Age, BMI and sex dependent | |
| Hormones | |||||||
| IGF-1 | ECLIA |
Serum Plasma |
Yes | Yes | No preanalytical constrains | Age and sex dependent | |
| DHEAS |
LC–MS/MS ECLIA |
Serum Plasma |
Yes | Yes | No preanalytical constrains | Age and sex dependent | |
| BV described | |||||||
| Cortisol |
LC–MS/MS ECLIA |
Serum Plasma Saliva Urine |
Only with ECLIA | Yes | Standardize time of collection for blood |
Circadian rhythm BV described |
Prefer use of total rather than free hormone Prefer use of serum/plasma |
| Testosterone |
LC–MS/MS ECLIA |
Serum Plasma |
Yes | Yes |
Fasting Morning collection (between 7 and 10 AM) |
Age and sex dependent BV described |
Prefer use of total rather than free hormone |
| Inflammatory markers | |||||||
| CRP | Turbidimetric |
Serum Plasma |
Yes | Yes | 24 h exercise-free period | BV described | Prefer use of ultrasensitive method |
| IL-6 |
ELISA Cytokine panel ECLIA |
Serum Plasma |
Yes | Yes | 24 h exercise-free period | BV described | |
| TNF-α |
ELISA Cytokine panel |
Serum Plasma |
Yes | Yes | 24 h exercise-free period | BV described | |
GDF-15 growth factor differentiation-15; CAF C-terminal agrin fragment; BDNF brain-derived neurotrophic factor; PIIINP N-terminal type 3 procollagen; IGF-1 Insulin-like growth factor-1; DHEAS dehydroepiandrosterone sulphate; CRP C-reactive protein; IL-6 interleukin-6; TNF-α tumor necrosis factor-α; LC–MS/MS Liquid chromatography and tandem mass spectrometry; ELISA enzyme-linked immunosorbent assay; ECLIA electrochemiluminescence immune assay; BV biological variation
* Fasting or 24 h exercise-free period are optional constrains when not mentioned