Generalized loss of muscle mass of non-senile origin

Specialty: General.

• diffuse muscle atrophy
• muscle cachexia
• generalized muscle wasting
• systemic muscle wasting

Why it occurs

• Severe endocrine myopathies (uncontrolled thyrotoxicosis, primary or secondary hypercortisolism due to accelerated protein degradation)
• Chronic malabsorption disorders (undiagnosed celiac disease, exocrine pancreatic insufficiency, tropical sprue or Crohn's disease affecting the small intestine)
• Prolonged immobility or forced bed rest due to non-critical medical pathologies (muscle disuse that activates protein ubiquitination pathways)
• Motor neuron disease or multifocal chronic demyelinating peripheral neuropathies (loss of muscle trophic innervation)
• Selective protein malnutrition due to extreme unbalanced diets or severe food restriction.

Initial workup

Total creatine phosphokinase (CPK), aldolase, needle electromyography and nerve conduction velocity, 24-hour urinary free cortisol levels, anti-tissue transglutaminase IgA antibodies, and computed tomography or thigh muscle MRI.

Standard management

• Supplementation with branched chain amino acids — BCAA, 5 to 10 g per day orally to stimulate mTOR protein synthesis pathways
• Creatine monohydrate — 3 to 5 g per day orally to promote muscle intracellular water retention and energy support
• Vitamin D3 (1000 to 2000 IU daily orally if there is a deficiency to promote the function of the vitamin D receptor in the myocyte).