Electrolyte Balance 1: Sodium, Potassium, Magnesium Flashcards
hyponatremia numerical definition
Na < 135 mmol/L
effects of hyponatremia
◾ When sodium levels drop below 120 mmol/L, individuals may experience general weakness and fatigue.
◾ At sodium levels below 110 mmol/L, more severe CNS symptoms can occur, including confusion, seizures, and altered mental status.
◾ Below 105 mmol/L, individuals are likely to go into coma.
List 3 types of hyponatremia.
(1) hyperosmotic hyponatremia
(2) isosmotic hyponatremia (pseudohyponatremia
(3) hypoosmotic hyponatremia
Briefly outline causes hyperosmotic hypernatremia.
◾ hyperglycemia: high blood sugar levels cause water to ove out of cells into the bloodstream, diluting sodium levels
◾ mannitol: This osmotic diuretic can increase plasma osmolality, leading to water movement into the bloodstream and dilution of sodium.
◾ high urea: Elevated urea levels can also contribute to hyperosmotic hyponatremia by drawing water into the bloodstream.
Briefly outline causes of isosmotic hypernatremia (aka. pseudohyponatremia).
Hyperlipidemia and hyperproteinemia can interfere with sodium measurement, resulting in false readings that indicate apparent hyponatremia
Briefly outline causes of hypoosmotic hypernatremia.
(i) Dilutional causes
◾ Congestive Cardiac Failure can lead to fluid retention and dilution of sodium.
◾ Renal Failure can cause fluid retention and dilutional hyponatremia.
◾ Liver disease can lead to fluid accumulation in the abdomen (ascites) and dilution of sodium.
(ii) Depletional causes
◾ Renal losses: conditions like diuretic use or adrenal insufficiency can cause excessive sodium loss through the kidneys.
◾ GIT losses: vomiting, diarrhea, nasogastric suction can lead to significant sodium loss.
◾ Skin losses: excessive sweating or burns
◾ Inadequate dietary intake
hypernatremia numerical definition
Na > 145 mmol/L
effects of hypernatremia
(a) Peripheral and systemic symptoms
◾ Dyspnea: Shortness of breath, often due to fluid overload affecting the lungs.
◾ Pulmonary edema: Fluid accumulation in the lungs, leading to breathing difficulties.
◾ Venous congestion: Increased pressure in the veins, often visible as distended neck veins.
◾ Hypertension: Elevated blood pressure due to increased fluid volume.
◾ Effusions: Accumulation of fluid in body cavities, such as pleural effusion (fluid around the lungs) or ascites (fluid in the abdomen)
◾ Weight gain: Rapid weight gain due to fluid retention.
◾ Peripheral edema: Swelling in the extremities due to fluid retention.
(b) CNS symptoms
tremors, irritability, ataxia, confusion, coma, hemiplegia (less common)
hypernatremia causes
(1) Pure water loss
◾ hypodipsia: reduced sensation of thirst, leading to inadequate water intake
◾ unreplaced insensible losses: loss of water through skin and respiratory tract that is not compensated by adequate fluid intake
◾ diabetes insipidus: characterized by excessive urination and thirst due to a deficiency of antidiuretic hormone
(2) Hypotonic fluid losses
◾ diuretics: increase urine production, leading to disproportionate loss of water and sodium
◾ polyuric phase of acute renal failure: a phase where the kidneys produce large amounts of dilute urine leading to fluid loss
◾ vomiting and diarrhea, enteric fistulae, laxatives
◾ cutaneous losses: burns, excessive sweating
(3) Hypertonic sodium gain
◾ Hypertonic infusions: administration of hypertonic saline or other sodium-containing solutions
◾ Dialysis: Use of hypertonic solutions during dialysis can lead to increased sodium levels.
◾ Cushing’s syndrome: A condition characterized by excessive production of cortisol, which can lead to sodium retention.
◾ Conn’s syndrome (primary hyperaldosteronism): A condition characterized by excessive production of aldosterone, leading to sodium retention and potassium loss.
Why is it important to inspect serum for lipaemia in hyponatremia?
Lipaemia can interfere with laboratory measurements, leading to inaccurate results. Inspecting the serum for lipaemia ensures that the test results are reliable and accurate.
normal range for Potassium?
3.5 - 5.0 mmol/L
List preanalytical causes of hyperkalemia.
(1) Haemolysis: The breakdown of red blood cells during or after blood collection can release potassium into the serum, artificially increasing its levels.
(2) Leucocytosis: A high white blood cell count can cause potassium to be released from cells during sample processing.
(3) Thrombocytosis: A high platelet count can similarly lead to potassium release during sample processing.
(4) Delayed Separation of Serum: If the blood sample is not promptly separated from the cells, potassium can leak from the cells into the serum, leading to falsely elevated levels.
What conditions cause a shift in sodium (Na) and potassium (K) leading to hyperkalemia?
acidosis [H+ ions enter cells in exchange for K+ ions, leading to hyperkalemia], tissue hypoxia [Na-K pump is disrupted], insulin insufficiency, crush injuries, and violent muscular activity.
These conditions cause potassium to move from cells into the bloodstream.
hyperkalemia signs and symptoms
muscle weakness, numbness and tingling, nausea and vomiting, irregular heart rhythm/cardiac arrest
management of hyperkalemia
(1) ECG monitoring to detect any changes in heart rhythm
(2) intavenous calcium gluconate: stabilizes cardiac membrane, reducing the risk of arrhythmias. It does not lower potassium levels but provides temporary protection for the heart.
(3) intravenous glucose and insulin: promote uptake of potassium into cells
(4) salbutamol: stimulates the sodium-potassium pump
(5) sodium bicarbonate: in the presence of acidosis, it helps shift potassium into cells by correcting acidosis and increasing blood pH
(6) dialysis: removes excess potassium form blood
(7) loop diurtetics: increase excretion of potassium through urine
(8) ion exchange resins
(9) dietary restrictions
