Adynamia

Specialty: General.

• lack of physical strength
• motor prostration
• weakness of movement
• incapacity of physical initiative

Why it occurs

• Severe hydroelectrolyte imbalances (hypokalemia, chronic hyponatremia or hypercalcemia, which alter the transmembrane action potential of muscle fibers and neuromuscular transmission)
• Congestive heart failure with low cardiac output (where peripheral muscle perfusion is insufficient to sustain basic motor activity)
• Inflammatory or metabolic myopathies (polymyositis, dermatomyositis or statin-induced myopathies, which cause degradation of muscle fibers)
• Acute adrenal insufficiency or Addison's crisis (critical deficiency of glucocorticoids and mineralocorticoids that prevents the normal hemodynamic and metabolic response)
• Myasthenia gravis or myasthenic syndromes (postsynaptic blockade of acetylcholine receptors at the neuromuscular junction).

Initial workup

Serum electrolytes with special attention to potassium, sodium and ionic calcium, total creatine phosphokinase (CPK), serum aldolases, morning cortisol with ACTH, arterial blood gases to evaluate acid-base balance, and electromyography of extremities.

Standard management

• Potassium chloride — depending on the calculated deficit, usually 20 to 40 mEq per day orally or controlled slow intravenous infusion, to restore muscle membrane potential
• Hydrocortisone — 15 to 25 mg per day divided into two or three doses, in case of confirmed adrenal insufficiency
• Pyridostigmine (60 mg orally every 6 hours under strict neurological supervision if neuromuscular junction pathology is confirmed).