METABOLIC MEDICINE MADE SIMPLE : HYPONATREMIA : CAUSES , PATHOPHYSIOLOGY & CLINICAL FEATURES

HYPONATREMIA  : CAUSES , PATHOPHYSIOLOGY & CLINICAL FEATURES

HYPONATREMIA

DEFINITION

Hyponatremia is a low sodium concentration in the blood. 

It is generally defined as a sodium concentration of less than 135 mmol/L (135 mEq/L), with severe hyponatremia being below 120 mEq/L. 

Symptoms can be absent, mild or severe. Mild symptoms include a decreased ability to think, headaches, nausea, and poor balance.

CAUSES OF HYPONATREMIA

HYPOVOLEMIC VOLUME STATUS

Total body water is lower than normal status

Diuretics

Sodium losing Disorders

Mineralocorticoid Deficiency

Vomiting

Diarrhea

Gastroenteritis

Burns

EUVOLEMIC

Total body water is in its normal range

SIADH

Glucocorticoid Deficiency

Hypothyroidism

HYPERVOLEMIC

Total body water is more than its normal range

Cardiac Failure

Hepatic Failure

Nephrotic Syndrome

PATHOPHYSIOLOGY

Gradual and longterm lowering of sodium concentration is mich well tolerated than a rapid acute fall of sodium levels.

Patients with mild hyponatremia are usually asymptomatic ( 125 – 135 mmol/l of sodium levels.)

Patients with moderate hyponatremia ( sodium 115 – 125 mmol/l) may have nausea , lethargy ,headache and dosorientation.

Patients with severe hyponatremia ( sodium of less than 115 mmol/L) can suffer from seizures ,coma and even death

CLINICAL FEATURES OF HYPONATREMIA

Hyponatremia signs and symptoms may include:

Nausea and vomiting

Headache

Confusion

Loss of energy, drowsiness and fatigue

Restlessness and irritability

Muscle weakness, spasms or cramps

Seizures

Coma