Sodium Deficiency (Hyponatremia): Causes

Pathogenesis (development of disease)

Forms of hyponatremia:

  • Hypertonic hyponatremia: in the presence of increased concentrations of other osmotically effective substances, usually glucose. The osmotic gap is greater than 10 mosmol/L.
  • Hyponatremia in polydipsia (excessive thirst).
  • Hyponatremia in euvolemia (total body sodium in the normal range).
    • Urine Na+ > 30 mmol/L
      • Syndrome of inadequate ADH secretion (SIADH) (synonym: Schwartz-Bartter syndrome) – there is an inappropriately high secretion of antidiuretic hormone (ADH; ADH excess) in relation to blood plasma osmolality; this leads to inadequate renal fluid excretion with the formation of highly concentrated urine; the result is hyperhydration (overhydration) with dilutional hyponatremia (“dilutional sodium deficiency”), which can lead to cerebral edema (brain swelling). Etiology (causes): paraneoplastic in approximately 80% of cases in patients with small cell lung cancer; other possible causes include:
        • CNS (central nervous system) diseases: intracranial hemorrhage (bleeding within the skull; parenchymal, subarachnoid, sub- and epidural, and supra- and infratentorial hemorrhages)/intracerebral hemorrhage (ICB; brain hemorrhage), brain tumors, Guillain-Barré syndrome, infections, meningitis (meningitis), encephalitis (brain inflammation), multiple sclerosis (MS)
        • Pulmonary diseases (lung diseases): pneumonia (pneumonia/insb. Legionella pneumonia (pneumonia caused by the pathogen Legionella pneumophilia)), bronchial carcinoma (small cell and non-small cell), emphysema (lung hyperinflation), chronic obstructive pulmonary disease (COPD), tuberculosis.
        • Malignant (malignant) diseases: Carcinomas (lung, ENT area, gastrointestinal and genitourinary tract gastrointestinal tract and urinary and genital tract), lymphomas, sarcomas.
        • Medications: Antidepressants, antiepileptics, anticonvulsants, antipsychotics, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids.
        • Miscellaneous: Vasopressin-2 receptor mutations, giant cell arteritis, idiopathic.

        Symptoms: Nausea (nausea), loss of appetite, cephalgia (headache) posed.

    • Hypercorticism
    • Hypothyroidism (underactive thyroid gland)
    • Water intoxication (water hydration; overhydration): in this case, the osmolarity in the urine is less than in the serum
    • Primary polydipsia (excessive thirst; “psychogenic polydipsia”).
      • Excessive intake of hypotonic solutions
      • After transurethral resection of the prostate (TURP).
    • Sports extreme loads
  • Urine Na+ < 30 mmol/L
    • As under the previously mentioned causes with concomitant low salt intake.
  • Hyponatremia in hypovolemia (decrease in the amount of blood circulating, i.e., in the bloodstream).
  • Hyponatremia in hypervolemia (increase in the volume of circulating blood, i.e., in the bloodstream).
    • Urine Na+ > 30 mmol/L
      • Chronic renal failure – process leading to a slowly progressive reduction in renal function.
    • Urine Na+ < 30 mmol/L
      • Heart failure (cardiac insufficiency)
      • Liver cirrhosis (irreversible (non-reversible) damage to the liver associated with marked remodeling of liver tissue) with ascites (abdominal dropsy) (liver failure)
      • Nephrotic syndrome – collective term for symptoms that occur in various diseases of the glomerulus (renal corpuscles); the symptoms are proteinuria (increased excretion of protein in the 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).

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
    • Increased fluid intake (water intoxication).
    • Inadequate intake of sodium and table salt.
    • Micronutrient deficiency (vital substances) – sodium
  • Consumption of stimulants
    • Alcohol (in this case, elderly people with long-term malnutrition + more than five liters of beer every day → 4.5 percent of patients with hyponatremia and values below 135 mmol/l;1.3 percent) of patients showed severe hyponatremia (below 125 mmol/l), the lowest value was 104 mmol/l)
  • Drug use
    • Ecstasy (also XTC, Molly, etc.) – methylenedioxymethylamphetamine (MDMA); dosage on average 80 mg (1-700 mg); structurally belongs to the group of amphetamines.

Disease-related causes.

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

  • Hypercorticism (Cushing’s disease: hypercortisolism; excess of cortisol).
  • Hypothyroidism (hypothyroidism).
  • Adrenocortical insufficiency (NNR insufficiency; adrenocortical weakness).
  • Syndrome of inadequate ADH secretion (SIADH; there is an inappropriately high secretion of antidiuretic hormone (ADH) in relation to blood plasma osmolality; this leads to too little fluid excretion by the kidneys with the emergence of an insufficiently diluted urine); occurrence in cerebral hemorrhage, brain tumor, meningitis (meningitis), encephalitis (brain inflammation), tuberculosis, pneumonia (pneumonia), carcinoma

Cardiovascular system (I00-I99).

  • Heart failure (cardiac insufficiency)
  • Hypotension (low blood pressure)

Infectious and parasitic diseases (A00-B99).

  • Diarrhea (diarrhea)

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

  • Liver cirrhosis (irreversible damage to the liver associated with marked remodeling of liver tissue) with ascites (abdominal dropsy).
  • Pancreatitis (inflammation of the pancreas).

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

  • Ileus (intestinal obstruction)
  • Peritonitis (inflammation of the peritoneum)

Psyche – nervous system (F00-F99; G00-G99)

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

  • Vomiting
  • Diarrhea (diarrhea)
  • Polydipsia (excessive thirst)

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

  • Chronic renal failure (slowly progressive reduction in renal function).
  • Nephrotic syndrome – collective term for symptoms that occur in various diseases of the glomerulus (renal corpuscles); the symptoms are proteinuria (increased excretion of protein in the 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).
  • Salt loss kidney

Injuries, poisonings and other consequences of external causes (S00-T98).

  • Muscle trauma
  • Burns

Operations

  • Transurethral resection of the prostate (TURP; removal of the prostate through the urethra).

Other causes

Medication

1 Drugs that stimulate the release of antidiuretic hormone (ADH) 2 Drugs that exogenously supply ADH 3 Drugs that may potentiate the action of ADH 4 Drugs that may cause hyponatremia of unclear etiology.