ELECTROLYTES Flashcards
Ions that are capable of carrying an electric charge
Electrolytes
Fluid that is one third of the total body water
16 Liters
Extracellular fluid
Fluid that is two thirds of the total body water
24 L
Intracellular fluid
Major Extracellular Cation, hence the major contributor of Osmolality
Sodium
Sodium’s plasma concentration depends greatly on the intake and excretion of __
Water
Reference Value of Sodium
135 - 145 mmol/L
Promotes absorption of sodium in the distal tubule
Promotes sodium retention and potassium excretion
Aldosterone
Blocks aldosterone and renin secretion, and inhibits the action of angiotensin II and vasopressin
Causes Natriuresis
Atrial Natriuretic Factor (ANF)
- Diabetes insipidus
- Renal tubular disorder
- Prolonged diarrhea
- Profuse sweating
- Severe burns
- Vomiting
- Fever
- Hyperventilation
Excess Water Loss
Hypernatremia
- Hyperaldosteronism (Conn’s disease)
- Sodium bicarbonate infusion
- Increased oral or IV intake of NaCl
- Ingestion of sea water
Increased water intake or retention
Hypernatremia
- Diuretic use
- Saline infusion
Increased Sodium loss
Hyponatremia
- Renal failure
- Nephrotic syndrome
- Aldosterone deficiency
- Cancer
- Syndrome of Inappropriate ADH Secretion
- Hepatic cirrhosis
- Primary polydipsia
- CNS abnormalities
- Myxedema
Increased water retention
Hyponatremia
Defined as an increased sodium concentration in plasma water,
Sodium levels >145 mmol/L
Caused by loss of water, gain of sodium or both
Hypernatremia
Most common electrolyte disorder
Reduced plasma sodium concentration <135mmol/L
Hyponatremia
Reduction in serum sodium concentration caused by a systematic error in measurements
Pseudohyponatremia
Most common, yet not widely known cause of pseudohyponatremia is ___, a well known cause of pseudohyperkalemia
In Vitro Hemolysis
- Serum Na - Low
- Urine Na - Low
- 24-hour Na - Low
- Urine Osmolality - Low
- Serum K - N/L
Overhydration
- Serum Na - Low
- Urine Na - Low
- 24-hour Na - High
- Urine Osmolality - Low
- Serum K - Low
Diuretics
- Serum Na - Low
- Urine Na - High
- 24-hour Na - High
- Urine Osmolality - High
- Serum K - N/L
SIADH
- Serum Na - Mildly elevated
- Urine Na - Normal
- 24-hour Na - N/A
- Urine Osmolality - High
- Serum K - High
Adrenal Failure
- Serum Na - Low
- Urine Na - Low
- 24-hour Na - High
- Urine Osmolality - Low
- Serum K - Low
Bartter’s Syndrome
- Serum Na - Low
- Urine Na - Normal
- 24-hour Na - Normal
- Urine Osmolality - Normal
- Serum K - High
Diabetic Hyperosmolality
Methods used for detection of Sodium levels:
- Emission Flame Photometry
- Ion Selective Electrode (Glass Aluminum silicate)
- Atomic Absorption Spectrophotometry
- Colorimetry
Major Intracellular Cation
Single most important analyte in terms of abnormality being immediately life threatening
Potassium
Potassium has a concentration in the RBCs of ___ which is __x its concentration in plasma
105 mmol/L
23x
It is reabsorbed together with Na & Cl by the sodium potassium chloride cotransporter in:
Ascending limb of Henle’s Loop
Reference Value of Potassium:
3.5 - 5.2 mmol/L
Reference Value of Potassium:
3.5 - 5.2 mmol/L
Plasma levels are ___ compared to serum levels because of the release of platelets into serum on clot formation
LOWER
- Acute or Chronic Renal Failure
- Severe Dehydration
- Addison’s Disease
Hyperkalemia due to
Decreased renal excretion
- Acidosis
- Muscle/Cellular injury
- Chemotherapy
- Vigorous exercise
- Digitalis intoxication
Hyperkalemia due to
Extracellular shift
Other causes of Hyperkalemia:
Increased intake
Use of immunosuppressive drugs
- Gastric suction & Laxative abuse
- Intestinal tumor and malabsorption
- Cancer and Radio therapy
- Vomiting and Diarrhea
Hypokalemia due to
Gastrointestinal loss
- Diuretics use
- Hyperaldosteronism
- Cushing’s Syndrome
- Leukemia
- Bartter’s Syndrome
- Gitelman’s Syndrome
- Liddle’s Syndrome
- Malignant Hypertension
Hypokalemia due to
Renal Loss
- Alkalosis
- Insulin Overdose
Hypokalemia due to
Intracellular Shift
Almost always due to impaired Renal Excretion
Hyperkalemia
Elevations in serum K can directly stimulate the adrenal cortex to release:
Aldosterone
Three major mechanisms of diminieshed renal potassium:
- Reduced aldosterone
- Renal Failure
- Reduced distal dedlivery of sodium
Most common cause of chronic hyperkalemia due to impaired renal excretion of plasma is ____, which is caused by chronic renal insufficiency of primarily tubulointerstitial disease
Hyporeninemic Hypoaldosteronism
Reduced GFR and decreased tubular secretion causes accumulation of potassium (Mg, PO4) in plasma
Renal Failure
Plasma K levels of ___ is fatal and can cause cardiac arrest
10 mmol/L
Hyperkalemic drugs:
- Captopril
- Spironolactone
- Digoxin
- Cyclosporine
- Heparin
- Sample Hemolysis
- Thrombocytosis
- Prolonged Tourniquet Application
- Fist Clenching
- Blood stored in ice
- IV fluid
- High blast counts in acure or accelerated phase leukemias
Causes of Pseudohyperkalemia
Hpomagnesemia leads to ___ by promoting urinary loss of potassium
Hypokalemia
Most common cause of hypokalemia
Can be attributed to increased activity of aldosterone or other mineralocorticoid
Impaired Renal function or Renal Loss