​Kembara Xtra - Medicine - Hyponatremia

​Kembara Xtra - Medicine - Hyponatremia 
A plasma sodium (Na+) concentration below 135 mEq/L is considered hyponatremia.
Hyponatremia by itself cannot tell you how much water the patient has in their body (TBW). Patients who have hyponatremia can have hyper-, hypo-, or euvolemia.

Endocrine/metabolic, renal, cardiovascular, and central nervous system (CNS) system(s) affected

Epidemiology Incidence: Males outnumber females in terms of the most prevalent electrolyte problem found in the general hospital population.
2.5% of hospitalized patients, 20–30% of inpatient patients, and 7.7% of outpatients are the prevalence. 

Aspects of Geriatrics

Elderly people are at risk for decreased urine concentration and impaired antidiuretic hormone response due to their decreasing renal mass. The glomerular filtration rate will also be impacted by their lower TBW condition, diminished thirst mechanism, and decreased renal blood flow. Frequent falls and abnormal gait patterns are two symptoms that may be present.
Child Safety Considerations
Children under the age of 16 have less intracranial space and are more likely to develop cerebral edema, which increases the risk of brain herniation.

Pathophysiology and Etiology 
To diagnose the etiology and guide management, it is necessary to determine the volume status and serum osmolality.

Hypertonic hyponatremia: serum osmolarity (Osm) > 295 mOsmol/kg - Dilution occurs as a result of water shifting from intracellular fluid (ICF) to extracellular fluid (ECF).
 Maintaining TBW and Na+
Isotonic hyponatremia ("pseudohyponatremia") is characterized by serum osmolality between 275 and 295 mOsmol/kg, excessive osmoles that dilate the blood, and unaltered TBW and Na+.
- Causes include laboratory artifacts, hyperlipidemia, hyperproteinemia (including multiple myeloma), and irrigant solutions.
Hypovolemic hyponatremia is characterized by low TBW and low Na+ levels. Hypotonic hyponatremia is defined as serum Osmol/kg 275 mOsmol/kg.
Orthostatic hypotension, a reduction in skin turgor, and dry mucous membranes are symptoms.
Urine Na+ >30 mmol/L indicates renal loss such as cerebral salt wasting, adrenal insufficiency, diuretics, and osmotic diuresis. Urine Na+ 30 mmol/L indicates extrarenal loss such as GI loss (vomiting, diarrhea), third-spacing (pancreatitis, burns), skin loss (burns, cystic fibrosis, sweating), and heat-related illnesses.
The most typical subtype of euvolemic hyponatremia manifests as a modest to moderate rise in TBW and normal Na+, among other symptoms.
If urine Osm is greater than 100 mOsm/kg, possible causes include syndrome of inappropriate antidiuretic hormone (SIADH), hypothyroidism, adrenal insufficiency, and drugs such as thiazide diuretics, loop diuretics, carbamazepine, clofibrate, cyclosporine, levetiracetam, oxcarbazepine, SSRIs, and TCAs.
If urine Osm is less than 100 mOsm/kg, primary polydipsia, beer potomania, and exercise-induced hyponatremia are the most common causes.
Increased TBW and Na+ in hypervolemic hyponatremia
One symptom is an edematous condition.
Congestive heart failure (CHF), cirrhosis, nephrotic syndrome, hypoalbuminemia, and psychogenic polydipsia are some of the causes of urine Na+ levels that are below 30 mmol/L.

Polymorphisms have been proven in genetics.
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD; SIADH) has been linked to mutations.

Prevention is dependent on the underlying cause.

Cirrhosis, hypopituitarism, hypothyroidism, and CHF are all associated conditions.

HIV patients, adrenocortical hormone deficit, and nephrotic syndrome

SIADH has been linked to HIV infection, cancer, pneumonia, TB, encephalitis, meningitis, head trauma, and cerebrovascular accidents.
Traumatic brain damage, running marathons in hot weather, beer potomania, the tea-and-toast diet, and Ecstasy use are just a few examples.

Diagnosis: The rate of serum Na+ decline, the start, and the severity of hyponatremia are all correlated with the symptoms.

Acute (less than 48 hours): unable to fully adapt, more likely to appear with moderate or severe symptoms
Chronic (more than 48 hours): slow onset, organ systems adjust to Na+ concentration, little symptoms
Mild (serum Na+ 130–135 mEq/L): typically asymptomatic, exhaustion, and appetite loss
Moderate (serum Na+ 120 to 130 mEq/L): dizziness, nausea, and fatigue
Serum Na+ 115 to 120 mEq/L: severe: headache, drowsiness, restlessness, and confusion
A severe or sudden drop in serum Na+ levels may be lethal and result in seizures, coma, brain herniation, respiratory arrest, and other conditions.
Additional symptoms include cranial nerve palsies, orthostatic hypotension, anorexia, hiccups, depressed deep tendon reflexes, hypothermia, and positive Babinski responses.

Caution 
Osmotic gradients between plasma and cells are caused by low Na+ levels, which cause fluid to move into the cells. As a result, cerebral edema and intracranial pressure rise, which may finally result in hyponatremic encephalopathy and brain herniation.

The symptoms include a headache, nausea, vomiting, and cramps in the muscles.
May develop into lethargy, agitation, or confusion.

clinical assessment 

Skin turgor, jugular venous pressure, heart rate, and an orthostatic blood pressure reading serve as indicators of volume status.
Check for indicators of underlying illness, such as hypothyroidism, cirrhosis, or CHF.
Reflexes might be lessened.

Laboratory Results 

Initial examinations (lab, imaging)
Comprehensive metabolic profile (liver function tests, BUN, creatinine, glucose, electrolytes, etc.)
Lipid panel, serum osmolality, urine Na+ and osmolality, thyroid-stimulating hormone (TSH), and chest x-ray to rule out pulmonary pathology if SIADH is diagnosed


Tests in the Future & Special Considerations

If a pituitary issue or SIADH resulting from a CNS issue is suspected, a CT scan of the head should be performed.

Management 

 Examine every drug the patient is currently taking.
Establish seizure safety measures.
Implement fluid restriction for patients who are hypervolemic.
The administration of fluids to hypovolemic individuals. Acute hyponatremia, symptomatic hyponatremia, and relationship with intracranial disease already at risk for cerebral edema are indications for using 3% hypertonic saline instead of regular saline solution.


Medication Warning 

Central pontine myelinolysis, a neurological condition characterized by the loss of myelin and supporting structures in the pons and infrequently in other regions of the brain, has been linked to the rapid cure of severe symptomatic hyponatremia. This causes harm that cannot be repaired. Seizures, comas, spastic paraparesis, dysarthria, and difficulties swallowing are among the symptoms that surface 2 to 6 days following an injury.
Patients with Na+ 105 mEq/L, alcoholism, hypokalemia, malnutrition, and liver transplant recipients with severe liver disease are at a higher risk. Since an MRI may not be positive until 4 weeks after the onset of symptoms, it is not necessary for diagnosis.

● The origin, severity of hyponatremia, onset, and symptomatology all influence the course of treatment.
● Some general guidelines are relevant:
- Selected infusate's anticipated effect on serum Na+:
Na is calculated as [(infusate Na+ + infusate K+-serum Na+) / (TBW + 1)]
- TBW = a weight (kg) coefficient, as shown in the following table:
- A correction formula can be found at http://www.medcalc.com/sodium.html.
Fluid restriction can be used to treat euvolemic, asymptomatic patients; however, the pathophysiology must be addressed.
● Give patients who are significantly hyponatremic or exhibiting symptoms 3% hypertonic saline, 2 mL/kg up to 100 mL, over a 20-minute interval. Assess the serum Na+ levels following infusion. Continue until there is a 5 mmol/L increase in serum Na+. ICU admission with Na+ checks every two hours.
- Discontinue using the hypertonic saline and switch to a 0.9% isotonic saline solution if symptoms improve after a 5 mmol/L rise. Serum Na+ should be raised by a maximum of 10 mmol/L during the first 24 hours, followed by 8 mmol/L per day until serum Na+ reaches 130 mmol/L.
– Continue the hypertonic saline infusion until a 1 mmol/L/hr increase in serum Na+ is reached if symptoms do not go away after a 5 mmol/L increase. If symptoms get better, serum Na+ rises by 10 mmol/L, or it reaches 130 mmol/L, stop the infusion.
● Use isotonic saline solution (0.9%) for mild to moderate hyponatremia. Consider seeking a specialist's advice before administering hypertonic saline (3%) by central venous access at a rate of 1 to 2 mL/kg/hr, raising serum Na+ levels by 0.5 mmol/L/h, and checking the plasma Na+ level periodically (about every two hours).
Consider using vasopressin V2-receptor antagonists, such as tolvaptan or conivaptan, in individuals with severe hyponatremia (euvolemic and hypervolemic state) who do not react to the aforementioned method.

Treat the root cause.
If fluid restriction alone is ineffective for treating chronic hyponatremia brought on by SIADH, demeclocycline (which inhibits ADH action in the collecting duct) should be used.
Drug generates nephrogenic diabetes insipidus at dosages of 600 to 1,200 mg/day. Contraindications include drug allergy, pregnancy, and children under the age of 8.
- Important potential interactions include penicillin, oral contraceptives, and oral anticoagulants. Re-lower the Na+ concentration in the event of an overcorrection.
Start with an hour-long infusion of 3 mL/kg of 5% dextrose in water. Measure Na+ once more. Be careful; dextrose infusion rates greater than 250 to 300 mL/hr have been shown to cause severe hyperglycemia in both diabetic and non-diabetic patients. They can also cause osmotic diuresis, which can result in free water loss and an increase in serum Na+ levels. To avoid overcorrection, think about administering 2 to 4 g of IV desmopressin every 8 hours.
Whole Body Water
Children weigh 0.6 pounds, women 0.5 pounds, and men 0.6 pounds.
Older women's weight, 0.45
Older males 0.5 pounds
ALERT
Exercise extreme caution and test serum Na+ as frequently as every one to two hours if the condition is severe. Hypertonic saline (3% Na+ chloride) with central line access may be an option.

Fluid restriction (euvolemia/hypervolemia) and fluid resuscitation (hypovolemia) are the first lines of treatment.
Vasopressin V2-receptor antagonists for secondary use


Admission 
If the patient exhibits symptoms or has acute hyponatremia (developing over less than 48 hours), which raises the risk of cerebral edema, admission is required.

If the patient is asymptomatic and has a serum Na+ level below 125 mEq/dL, admission is indicated.

Constant Care 
Euvolemic hyponatremia: Limit water intake to 1 to 1.5 liters per day.

 Hypervolemic Hyponatremia: Restricting Water and Na+

Hyponatremia is related with an increased risk of poor clinical outcomes and higher mortality in hospitalized patients; more recently, mild hyponatremia has been demonstrated to be an independent predictor of death in community-dwelling, middle-aged, and elderly persons.
Linked to patients with acute pulmonary embolism having a bad prognosis
Linked to a bad prognosis in liver cirrhosis patients and those awaiting liver transplants. Short-term graft loss and significant postoperative danger are both connected to it.

Complications 
If SIADH is found, an occult tumor can also be present.
If isotonic saline solution is used, hypervolemia may result.
If the Na+ level is adjusted too soon, osmotic demyelination (central pontine and extrapontine irreversible myelinolysis) may occur.

30% of new-onset seizures in intensive care units are caused by hyponatremia, which can also lead to hyponatremic encephalopathy and brain herniation, especially in young girls and children.
Chronic hyponatremia is linked to a higher risk of osteoporosis, attention deficit disorder, gait abnormalities, falls, and fractures.