Low sodium in the blood
Hyponatremia is a clinical condition in which the concentration of sodium in the blood is lower than normal. In physiological conditions, the concentration of sodium in the blood (natriemia or sodium) is maintained at levels between 135 and 145 mmol / L. We speak of hyponatremia (or hyponatremia) when this value falls below 135 mmol / L.
In the previous article on hyponatremia, we focused our attention on the possible causes. In this concluding discussion we will analyze the symptoms that characterize hyponatremia, diagnostic options and currently available therapies.
Symptoms
In hyponatremia, sodium serum concentrations are reduced, therefore there is an osmotic shift of water from the extracellular compartment to the intracellular compartment. The immediate consequence of this event is cytoplasmic swelling.
Medical statistics show that for sodium levels above 125 mmol / L and lower than 135 mmol / L (mild hyponatremia) the symptoms are light, vague, or completely absent. When present, the affected patient complains of gastrointestinal symptoms, especially nausea and vomiting. At lower sodium concentrations, the symptoms become more pronounced. In such situations, the following symptoms are often documented:
- Hallucinations
- Ascites (severe form)
- Ataxia
- Convulsions
- Muscle cramps
- Muscle weakness
- Disorientation
- Epilepsy
- Hypotension
- Headache
- Loss of consciousness
- Temporary memory loss
- Slow down of reflections
- Dry mouth
- Intense thirst
- Severe sleepiness
- Tachycardia
In severe cases, hyponatremia can induce coma, respiratory depression and death.
More in detail: what happens after a few hours from the onset of hyponatremia?
The body reacts with an adaptive response: the elimination of electrolytes from brain cells is promoted. A similar mechanism is important to limit as much as possible the entry of water into the intracellular site.
In the absence of treatment, after a few days there is a cellular loss of osmotically active molecules (myo-inositol, glycerophosphorylcholine, phosphocreatine / creatine, glutamate, glutamine and taurine).
The risk of permanent neurological complications is all the greater as the loss of these molecules is MORE QUICK:
- Chronic hyponatremia → sodium levels gradually decrease over a few days / weeks → more moderate signs and symptoms
- Acute hyponatrienia → blood sodium levels drop sharply: potentially fatal dangerous effects (brain swelling, coma, death)
Hyponatremia must be considered a serious pathological phenomenon, especially in the CNS: cellular edema can exert compression on the cerebral parenchyma, up to coma and death.
Diagnosis
A simple history and physical examination are not sufficient to establish a suspicion of hyponatremia. For diagnostic confirmation, it is necessary to proceed with blood and urine tests.
The evaluation of sodium is certainly one of the most widely used tests: hyponatremia is confirmed when blood sodium levels fall below 135 mmol / L.
Detection of sodium in urine > 20 mmol / L is an indication of hyponatremia due to renal decompensation / pathology and / or hormones that regulate its activity.
After having ascertained the alteration of sodium, it is necessary to proceed with a differential diagnosis of hyponatremia in order to trace the cause.
In some clinical situations, imaging tests may be useful: in the context of congestive heart failure, a chest radiograph is particularly indicated to ascertain hyponatremia. Brain CT may also be required in patients with evident altered consciousness.
therapies
In addition to being poorly tolerated by the patient, therapies for acute and chronic forms of hyponatremia are often ineffective.
The choice of treatment for hyponatremia is dictated by the cause that arises at the origins and the gravity of the condition.
Chronic mild or moderate hyponatremia, caused by diuretic abuse or exaggerated administration of water, should be treated by correcting the dosage of drugs and limiting fluid intake → WATER RESTRICTION
Different discourse must be addressed for the severe and acute forms of hyponatremia:
- Intravenous administration of a sodium-based solution (hypertonic saline solutions)
- Hormone therapy: indicated for forms of hyponatremia dependent on Addison's disease (insufficiency of the adrenal gland)
- Administration of vasopressin receptor antagonists (reserved for patients with hyponatremia associated with liver cirrhosis, congestive heart failure and SIADH). Tolvaptan (eg Samsca) is particularly effective: starting therapy with a dose of 15 mg, to be taken once a day. The dose can be increased up to 60 mg / day, in order to reach an adequate level of sodium and blood volume.
- Administration of demeclocicline or lithium: indicated in the context of hyponatremia associated with SIADH. These drugs reduce the responsiveness of the collector tubule to ADH.
