Slideshow 5

Flashcards about Sodium imbalances

Where is most of the body's sodium found?

More than 95% of the body's sodium is found in the ECF, making it the most plentiful electrolyte in that compartment.

What’s the concentration of Sodium in the ICF?

Very low

What are normal sodium levels?

135 – 145 mEq/L

What is sodium’s primary role in the body?

Regulating water distribution

What level is considered Hyponatremia?

Lower than 135 mEq/L

What level is considered Hypernatremia?

Higher than 145 mEq/L

What effect does low serum sodium level have on body cells?

Hyponatremia results in a diluted ECF, allowing water to be drawn into the cells.

What effect does high serum sodium level have on body cells?

Hypernatremia results in a concentrated ECF, pulling water out of the cells.

How does the body maintain sodium balance through diet?

The kidneys regulate sodium. An intake of 1.5 g per day is adequate for most.

Which electrolyte disorder has the most hospitalizations?

Sodium hyponatremia

What are the two types of Hyponatremia?

Dilutional hyponatremia - due to excess water gain.

Depletional hyponatremia - due to excessive sodium loss.

What is acute hyponatremia?

Less than 48 hours

What is chronic hyponatremia?

More than 48 hours

What main factors can result in Hyponatremia?

Loss of sodium, gain of water, edematous states, shift of water from the cell to the ECF.

Where can sodium be lost from?

• Kidneys (e.g., diuretics, kidney disease)

• GI tract (e.g., vomiting, diarrhea)

• Skin (e.g., sweating, burns)

Where would a gain of water come from?

Excess water intake or high ADH secretion: Dilutes serum sodium concentration.

Causes dilutional hyponatremia

How do edematous states lead to hyponatremia?

• Cirrhosis

• Congestive Heart Failure (CHF)

• Nephrotic syndrome

  Mechanism: Fluid shifts into interstitial spaces → decreased effective circulating volume → triggers ADH & RAAS → water retention → hyponatremia

How does water shift from cells to ECF cause hyponatremia?

e.g. Hyperglycemia

• High glucose draws water out of cells

• Dilutes sodium in the ECF

Sodium drops by ~2 mEq/L for every 100 mg/dL increase in glucose

Key Point: Not sodium loss—dilution from osmotic water movement.

What is one effect of severe hyponatremia?

Severe hyponatremia can cause neurological issues

Hyponatremia with ECF volume excess

Fluid Volume Excess (FVE)

Hyponatremia with ECF volume deficit

Fluid Volume Deficit (FVD)

What is Encephalopathy?

A group of conditions that cause brain dysfunction

What happens with a decrease in sodium concentration?

Causes shift of water from ECF to ICF and results in cellular edema (swelling)

What is Brain Herniation?

1. Brain edema from defecit.

2. Increased intracranial pressure.

3. Herniation (pushed out of place). Brain pushed down through openings like the foramen magnum due to swelling or bleeding.

How does the brain protect itself from swelling due to hyponatremia?

The brain activates the sodium-potassium pump (NAKPase system) to push sodium out of the cells, which helps stop water from entering and making the swelling worse.

How can vomiting cause hyponatremia?

Direct loss of gastric fluid, sodium. Hyponatremia from vomiting will not be severe unless there is an excessive intake of only water.

How can diarrhea cause hyponatremia?

Loss of intestinal fluid

How does SIADH (syndrome of inappropriate antidiuretic hormone secretion) lead to hyponatremia?

Body makes too much ADH. Causing excessive water retention, leading to dilutional hyponatremia.

How does Adrenal insufficiency cause hyponatremia?

Adrenal creates aldosterone, insufficiency = deficiency. (Aldosterone retains the sodium). Reduced = increased renal loss of sodium.

How do you loose sodium through sweating?

It’s hypotonic, sodium concentration of 30-65 mEq/L. Excessive in hot dry climate, loss could be 1500ml/h

How does Salt-losing nephritis cause hyponatremia?

Kidney diseases that cause renal excretion of salt. Can be mild to severe

How do Diuretics cause hyponatremia?

Mostly common in thiazide diuretics, contributing to severe hyponatremia in hospitals.

How can oxytocin use during pregnancy lead to hyponatremia?

, like ADH, can cause water retention if improperly administered during labor, leading to hyponatremia and seizures.

How does Ecstasy (MDMA) cause hyponatremia?

Enhances the release of ADH from the hypothalamus, causing hyponatremia which can cause neurological symptoms.

Why does postoperative Hyponatremia happen?

Stress, anesthesia, and pain increase ADH levels.

How do Malignant tumors and SIADH lead to hyponatremia?

Cancer cells release a substance like ADH, leading to SIADH.

How do CNS disorders cause hyponatremia?

CNS disorders like head trauma or tumors can cause hyponatremia through SIADH or cerebral salt wasting (CSW).

What is Polydipsia?

Drinking lots of water, seen in psychiatric patients. Psychiatric drugs cause a dry mouth.

How does Endurance exercise cause hyponatremia?

Athletes' intake water only, that does not replenish the sodium.

What factors do clinical signs of hyponatremia depend upon?

The level of the sodium decrease, Speed of development (acute/chronic), Cause of hyponatremia, Age and gender differences, Early vs late symptoms.

What are the clinical manifestations of hyponatremia?

Nausea and vomiting, Abdominal cramps, Lethargy, Headache, seizures, respiratory arrest, coma

What are the clinical features of hyponatremia caused by water overload (FVE)?

Increased body weight, No significant edema, Because ~⅔ of retained water is inside cells (intracellular)

What are the clinical features of hyponatremia caused by sodium loss (FVD)?

• Associated with ECF (extracellular fluid) deficit.

• Symptoms: Weakness, Postural hypotensioN, Dizziness

Which type of hyponatremia has more severe symptoms: dilutional or depletional?

Dilutional hyponatremia has more severe symptoms than depletional hyponatremia.

Which has more severe symptoms: acute or chronic hyponatremia?

Acute hyponatremia causes more severe symptoms than chronic or slow-developing hyponatremia.

Why are women of childbearing age at higher risk from hyponatremia?

They have a higher risk of fatal outcomes, including irreversible brain damage or death.

What does Urinary Laboratory Data show in Hyponatremia due to sodium loss from a non-renal route (GI)?

Low urinary sodium level, indicating renal conservation of needed sodium.

What does Urinary Laboratory Data show in Hyponatremia due to SIADH?

High urinary sodium level.

What is the urine specific gravity in SIADH, and why?

High (≥1.020) – because the urine is concentrated despite low blood sodium.

What is the urine specific gravity in cerebral salt wasting (CSW)?

High – due to sodium and water loss.

What is the urine specific gravity in polydipsia (excess water intake)?

Low (<1.005) – because the urine is very dilute.

What is the urine specific gravity in adrenal insufficiency?

High – due to sodium loss and volume depletion.

What are the basic principles for Hyponatremia Treatment?

Increasing the sodium concentration at a safe rate and treating the underlying cause.

How is Sodium replacement done for sodium loss hyponatremia?

Sodium can be replaced orally (PO). In acutely ill patients – sodium is replaced IV- with sodium containing fluids.

How do you treat dilutional hyponatremia (too much water, not enough sodium)?

Limit fluid intake (not just water). Keep it under 1 to 1.5 liters per day. This helps bring sodium levels back to normal (125–135 mEq/L) Used for people with too much water but no symptoms

How is hyponatremia with neurologic symptoms treated?

• Treated with hypertonic saline in the ICU for close monitoring.

• A volumetric pump (IVAC) is used to control how fast the saline goes in.

• Sodium levels must be checked frequently.

• Watch for fluid overload, especially in heart patients.

• Monitor for worsening neurologic signs, which can mean brain damage if sodium is corrected too quickly.

• In acute hyponatremia, sodium levels must be raised slowly due to high risk.

• In chronic hyponatremia, sodium can be replaced more gradually.

What is CPM (central pontine myelinolysis)?

A result from shrinkage of neurons away from their myelin sheaths, due to rapid correction of hyponatremia.

What is the difference in sodium correction between symptomatic and asymptomatic hyponatremia?

In symptomatic hyponatremia (like when the patient has seizures or brain symptoms), sodium levels are corrected more quickly to prevent serious brain damage or death.

In asymptomatic hyponatremia, sodium is corrected much more slowly to avoid harming the brain by raising the levels too fast.

How do AVP (arginine vasopressin) receptor antagonists help treat hyponatremia caused by SIADH?

They block the action of ADH, helping the body get rid of extra water. This makes the sodium concentration in the blood go back to normal.

What is Hypernatremia?

A serum sodium level of above 145 mEq/L

What are the Hypernatremia causes?

Water Deprivation, Breastfeeding associated hypernatremia, Watery diarrhea, Insensible water loss, Excessive sodium intake, diabetes insipidus.

Why is Hypernatremia most often seen in patients who are 65 or older?

Decreased thirst mechanism and decreased ability of the kidneys to conserve water in times of need.

How is Breastfeeding associated with hypernatremia?

May be due to ether high level of sodium in breastmilk or inadequate lactation. Can be life threatening and damage neonates CNS.

What is Leading cause for hypernatremia in children?

Watery diarrhea. Increased water intake due to nausea, fever excessive sodium.

What is normal Insensible (not sensed) water loss?

Respiration + evaporation from the Skin = 1000 ml of water per day. Any increase of loss hyperthermia.

What is Diabetes Insipidus (DI)?

A condition caused by decrease in ADH (anti diuretic hormone) secretion or kidney resistance to ADH, leads to excessive urination and thirst.

What is Central Diabetes Insipidus?

DI caused by lack of ADH secretion, e.g. Head injury, brain surgery or idiopathic (50% of cases).

What is Nephrogenic Diabetes Insipidus?

DI caused by kidneys not responding to ADH, e.g. Electrolyte imbalances (e.g. hypercalcemia, hypokalemia), certain drugs (e.g. lithium).

What are Diabetes insipidus signs?

Polyuria (excessive urine) + Polydipsia (excessive drinking)

3-20 liters

What lab findings are seen in complete vs partial DI?

Complete - very low urine specific gravity and osmolality. Partial- some ability to concentrate urine, values are higher.

What can happen when if a patient with DI can’t drink enough fluids?

May develop hyperthermia and hyperosmolality due to dehydration, causing weight loss, tachycardia, shock.

How does the body normally prevent dehydration in DI?

An intact thirst mechanism help the patient drink enough to maintain sodium balance.

What is a specific clinical sign for Hypernatremia?

Dry and sticky mucus membranes

What are key laboratory findings in hyperthermia?

Sodium > 145 mEq/L. Osmolality > 295 mOsm/kg.

What is the urine specific gravity in hyperthermia due to dehydration?

High (>= 1.020). Kidneys conserve water.

What is the urine specific gravity in hyperthermia due to Diabetes Insipidus?

Low (<1.005). Kidneys can’t concentrate urine.

What is the urine specific gravity in hyperthermia due to excess salt intake?

Depends on hydration status.

When does Severe neurological damage tend to occur in Hypernatremia patients?

Damage tends to occur with acute elevations in sodium greater then 158 mEq/L

What is the sodium concentration of patients with chronic hypernatremia who are usually mildly symptomatic?

Between 170-180 mEq/L

What is an Early sign of Hypernatremia?

Thirst - usually a protection. Hypernatremia will occur if mechanism is impaired or no access to water, e.g. elderly, disabled, infants, mental status.

What are early neutologicsl sign of hypernatremia?

Lethargy, weakness, irritability

What are progressed signs in severe hypernatremia?

Twitching, seizures, coma, death

Why may convulsions occur with an acute rapid increase in plasma sodium?

Due to cellular dehydration (resulting from pulling of fluid from the cells into the hyperosmotic ECF). Causing brain contraction > tearing of vessels > subarachnoid hemorrhage > permanent brain damage.

Why does Hypernatremia that developed within days to weeks (slow) is associated with minimal to mild neurological symptoms?

the CNS cells have time to adapt to hyperosmolar changes

Increased risk for thrombosis

Hemoconcentration = blood is thicker, reduced blood flow, endothelial damage in vessels

What happens to brain cells and how does the brain adapt to hypernatremia?

Too much sodium in blood pulls water out of cell, shrinking them cause confusion, bleeding or coma. After few hours brain creates particles (osmolytes) to retain water - adapts to stop further shrinking.

Why is the rapid correction of hypernatremia Dangerous?!

Blood becomes too diluted. Water rushes into the brain cells and causes brain swelling - seizures, brain damage, death.

What is the recommended rate of correction of the serum sodium?

The maximal recommended rate of correction of the serum sodium is 0.5 mEq/L/hour

How do you add water for Hypernatremia – treatment?

PO/NG tube – the safest route.

IV fluids – hypotonic saline/D5% dextrose

How would you treat hypernatremia + FVD (hypovalemia)?

isotonic saline 0.9%. Expands the plasma volume while still lowering plasma concentration.

How would we treat Diabetes Insipidus?

Central - administer ADH - nasal spray, po, IV. Complication water retention = hyponatremia.

Careful fluid infusion.

how do Thiazides assist with Hypernatremia – treatment?

They act by decreasing the number of sodium ions that reach the distal tubules of the kidneys

What is the urinary output of DI vs SIADH?

High vs Low

What are the levels of ADH in DI vs SIADH?

Low vs High

What type of atremia is DI?

Hypernatremia

What type of Atremia is SIADH?

Hyponatremia

What do both DI and SIADH present with?

Excessive thirst

What is the hydration level of DI vs SIADH?

Dehydrated vs over hydrated

What is the fluid retention in DI vs SIADH?

Lose too much vs retain to much