Overhydrated

Overhydration, commonly referred to as water intoxication, is a medical condition in which excess body water dilutes sodium and other electrolytes, leading to hyponatremia. It can occur with rapid or excessive water intake, impaired water excretion, or a combination of both. Acute overhydration can be life-threatening if not promptly recognized.

Causes and risk factors include endurance exercise with high fluid intake, polyuria from kidney or endocrine disorders, psychogenic polydipsia, certain medications (thiazide diuretics, selective serotonin reuptake inhibitors, antipsychotics), and conditions such as heart failure, liver cirrhosis, or SIADH.

Symptoms and diagnosis: Symptoms range from mild confusion, headache, nausea, and vomiting to seizures and coma in severe cases. Diagnosis relies on low serum sodium (<135 mmol/L), low plasma osmolality, and assessment of fluid status; urine osmolality and sodium help differentiate causes.

Treatment and management: Management depends on severity. Asymptomatic or mild hyponatremia: fluid restriction and addressing underlying cause. Symptomatic or severe hyponatremia: cautious administration of hypertonic saline (3% NaCl) under continuous monitoring, with rate limits to avoid rapid correction. Adjunctive measures may include salt tablets, diuretics, or vasopressin receptor antagonists in selected cases. Treat comorbid conditions. Correct sodium gradually to reduce risk of osmotic demyelination.

Prevention and prognosis: Prevention focuses on drinking according to thirst and electrolyte balance during prolonged exercise, avoiding excessive water intake, and monitoring medications that alter fluid balance. Early recognition improves prognosis; with prompt treatment, most patients recover, but severe cases may cause brain injury or death.