Too Much Sodium (Hypernatremia): Causes

Pathogenesis (development of disease)

The following forms of hypernatremia are distinguished:

  • Hypovolemic hypernatremia (= hypertonic dehydration): excessive sodium concentration with concomitant decreased intravascular volume (“in the vessels”); this results from:
    • Increased fluid excretion (urine, sweat).
    • disease-related, e.g.:
      • Deficiency of the antidiuretic hormone (ADH) due to failure of ADH production (partial (partial) or total; permanent or transient (temporary)), resulting in extremely high urine output (polyuria; 5-25 l/day) due to impaired concentrating ability of the kidneys.
      • By absent or insufficient response of the kidneys to ADH (ADH concentration is normal or even increased).
      • See below diseases
    • Medicinal
  • Hypervolemic hypernatremia (= hypertonic hyperhydration): excessive sodium concentration with concomitant increased intravascular volume; this results from excessive saline intake; causes are:
    • Alimentary (nutritional): seawater intoxication (drinking salt water).
    • Iatrogenic (e.g., infusion of hypertonic saline or sodium bicarbonate solution or sodium-containing penicillin salts).

Physiological serum osmolarity depends almost exclusively on sodium concentration. Thus, hypernatremia is accompanied by hyperosmolality (hyperosmolarity).Osmolality is the sum of the molar concentration of all osmotically acting particles per kilogram of solvent. In the case of hyperosmolality (hyperosmolal), a greater number of dissolved particles per kilogram of fluid is present than in the reference fluid. While intracellular (“inside the cells”) sodium concentration is controlled by Na+/K+-ATPase, regulation of sodium concentration of the extracellular space (space outside the cells) is via the renin-angiotensin-aldosterone system (RAAS) and atrial natriuretic peptide (ANP). For details, see “Saline/Regulation of Sodium Homeostasis.”

Etiology (Causes)

Behavioral causes

  • Diet
    • Decreased fluid intake
    • High intake of sodium and table salt
    • Micronutrient deficiency (vital substances) – potassium

Disease-related causes

Endocrine, nutritional and metabolic diseases (E00-E90).

  • Conn syndrome (primary hyperaldosteronism); aldosterone is a mineralocorticoid that, with other hormones such as renin and angiotensin, regulates fluid and electrolyte (blood salt) balance.
  • Diabetes insipidus centralis (synonyms: central (neurogenic) diabetes insipidus; diabetes insipidus neurohormonalis; hypoyphric diabetes insipidus – disorder in hydrogen metabolism caused by a deficiency of the antidiuretic hormone (ADH) due to failure of ADH production (partial (partial) or total; permanent or transient (temporary)), resulting in extremely high urine excretion (polyuria; 5-25 l/day) due to impaired concentrating capacity of the kidneys.
  • Cushing’s disease – group of diseases leading to hypercortisolism (hypercortisolism).

Infectious and parasitic diseases (A00-B99).

  • Diarrhea (diarrhea)

Liver, gallbladder, and biliary tract-pancreas (pancreas) (K70-K77; K80-K87).

Mouth, esophagus (esophagus), stomach, and intestines (K00-K67; K90-K93).

Symptoms and abnormal clinical and laboratory findings not elsewhere classified (R00-R99).

  • Fever (→ fluid losses).
  • Hyperglycemia (hyperglycemia → osmotic diuresis).
  • Hyperhidrosis (pathologically increased perspiration; night sweats; sweating; tendency to sweat; increase in sweat secretion; excessive sweating).
  • Hyperventilation (increased breathing, which goes beyond the need).
  • Polyuria (increased urine output).

Genitourinary system (kidneys, urinary tract – reproductive organs) (N00-N99)

  • Diabetes insipidus renalis (synonym: nephrogenic diabetes insipidus; ICD-10 N25.1) – disorder in hydrogen metabolism, caused by lack of or insufficient response of the kidneys to ADH (ADH concentration is normal or even increased), resulting in extremely high urine excretion (polyuria; 5-25 l/day) due to impaired concentration capacity of the kidneys.
  • Nephropathies (kidney disease) with impaired concentration capacity.
  • Nephrotic syndrome – collective term for symptoms that occur in various diseases of the glomerulus (renal corpuscles); the symptoms are proteinuria (increased excretion of protein with urine) with a loss of protein; hypoproteinemia, peripheral edema (water retention) due to hypoalbuminemia (decreased level of albumin in the blood), hyperlipoproteinemia (lipid metabolism disorder).
  • Renal insufficiency (process leading to a slowly progressive reduction in kidney function).
  • Polyuric renal failure (polyuria in ANV/acute renal failure).

Injuries, poisoning, and other sequelae of external causes (S00-T98).

Other differential diagnoses

  • Iatrogenic (e.g., infusion of hypertonic saline or sodium bicarbonate solution or penicillin salts containing sodium).
  • Increased perspiratio insensibilis (imperceptible loss of body water via skin (evaporation), mucous membranes, and respiration (moisture content of exhaled air)) – usually between 300-1,000 ml per day (data on the extent of perspiratio insensibilis vary widely in the literature)
  • Stoma (stoma carrier), fistulas.

Medication (with sodium-retaining effect or drug salt overload).