Unexplained loss of muscle mass, known as idiopathic sarcopenia, is a concerning condition where muscle seems to waste away or atrophy for no clear reason. This can happen even with adequate nutrition and exercise.
Some potential causes that doctors investigate include:
- Inflammatory diseases like cancer or autoimmune conditions
- Hormonal changes like low testosterone or thyroid levels
- Side effects of certain medications
- Nerve damage or muscle diseases
- Inadequate calories, protein, or vitamins despite a normal diet
Symptoms tend to develop slowly over months or years and may include:
- Feeling weaker and fatigue
- Difficulty with stairs, rising from chairs, household chores
- Clothes fitting more loosely even with a stable weight
- Tripping or stumbling more often
To diagnose idiopathic sarcopenia, doctors first rule out other explanations through:
- Physical exam to check muscle strength and mass
- Blood tests to check hormone, nutrient, and inflammatory levels
- Imaging like an MRI to see muscle composition
- Review of medication use and family history
If no cause is found, a diagnosis of exclusion of idiopathic sarcopenia may be made.
Treatment focuses on trying to rebuild muscle with:
- Resistance training with weights, bands, or bodyweight
- Getting adequate protein - up to 1.5 grams per kg body weight daily
- Taking certain supplements like creatine or amino acids
- Optimizing nutrition and controlling other diseases
- Consider trial of testosterone therapy if levels are borderline
While some people stabilize or improve with such interventions, unexplained muscle loss can unfortunately continue to worsen in some people despite treatment. Close follow-up with one's doctor is important, as is reporting any new or worsening symptoms. Researchers continue working to better understand the mechanisms behind idiopathic sarcopenia to hopefully develop better treatments one day.