SIADH is typically treated by correcting the underlying cause and with fluid restriction while high volume hyponatremia is typically treated with both fluid restriction and a diet low in salt. Correction should generally be gradual in those in whom the low levels have been present for more than two days.Hyponatremia is the most common type of electrolyte imbalance, and is often found in older adults. It occurs in about 20% of those admitted to hospital and 10% of people during or after an endurance sporting event. Among those in hospital, hyponatremia is associated with an increased risk of death. The economic costs of hyponatremia are estimated at $2.6 billion per annum in the United States. Signs and symptoms
Signs and symptoms of hyponatremia include nausea and vomiting, headache, short-term memory loss, confusion, lethargy, fatigue, loss of appetite, irritability, muscle weakness, spasms or cramps, seizures, and decreased consciousness or coma. Lower levels of plasma sodium are associated with more severe symptoms. However, mild hyponatremia (plasma sodium levels at 131–135 mmol/L) may be associated with complications and subtle symptoms (for example, increased falls, altered posture and gait, reduced attention, impaired cognition, and possibly higher rates of death).Neurological symptoms typically occur with very low levels of plasma sodium (usually <115 mmol/L). When sodium levels in the blood become very low, water enters the brain cells and causes them to swell (cerebral edema). This results in increased pressure in the skull and causes hyponatremic encephalopathy.
ATP binds to the myosin head and causes the ‘ratchetting’ that results in contraction according to the sliding filament model. Creatine phosphate stores energy so ATP can be rapidly regenerated within the muscle cells from adenosine diphosphate (ADP) and inorganic phosphate ions, allowing for sustained powerful contractions that last between 5–7 seconds. Glycogen is the intramuscular storage form of glucose, used to generate energy quickly once intramuscular creatine stores are exhausted, producing lactic acid as a metabolic byproduct. Contrary to common belief, lactic acid accumulation doesnt actually cause the burning sensation we feel when we exhaust our oxygen and oxidative metabolism, but in actuality, lactic acid in presence of oxygen recycles to produce pyruvate in the liver which is known as the Cori cycle.Substrates produce metabolic fatigue by being depleted during exercise, resulting in a lack of intracellular energy sources to fuel contractions. In essence, the muscle stops contracting because it lacks the energy to do so. Diagnosis
Grading
The severity of muscle weakness can be classified into different "grades" based on the following criteria:
Grade 0: No contraction or muscle movement. Grade 1: Trace of contraction, but no movement at the joint. Grade 2: Movement at the joint with gravity eliminated. Grade 3: Movement against gravity, but not against added resistance. Grade 4: Movement against external resistance with less strength than usual. Grade 5: Normal strength. Classification
Proximal and distal
Muscle weakness can also be classified as either "proximal" or "distal" based on the location of the muscles that it affects.