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
___ is the most common cause of extra renal loss of potassium
Diarrhea
___ can cause falsely decrease potassium levels because K is taken up by WBC
Leukocytosis
Methods to measure Potassium levels
- Emission Flame Photometry
- Ion Selective Electrode (Valinomycin gel)
- AAS
- Colorimetry (Lockhead & Purcell)
Major Extracellular Anion
Chief counter ion of sodium in ECF
Promotes maintenance of water balance & osmotic pressure
Chloride
Only anion to serve as an enzyme activator
Chlorine
Reference Value of Chlorine
98 - 107 mmol/L
Indicator: Diphenylcarbazone
End: HgCl2 (Blue-Violet)
Mercurimetric Titration
Schales & Schales
Mercuric Thiocyanate (Reddish)
Ferric Perchlorate
Spectrophotometric Method
Cotlove Chloridometer
Coulometric Amperometric Titration
Most commonly used method for detecting Chloride levels:
Ion Selective Electrode
- Renal Tubular Acidosis
- Diabetes insipidus
- Salicylate intoxication
- Primary hyperparathyroidism
- Metabolic acidosis
- Prolonged diarrhea
Hyperchloremia
(>107 mmol/L)
- Prolonged vomiting
- Aldosterone deficiency
- Metabolic Alkalosis
- Salt-losing nephritis
Hypochloremia
(<98 mmol/L)
Present almost exclusively in the plasma
Involved in blood coagulation, enzyme activity, excitability of skeletal and cardiac muscle, and maintenance of blood pressure
Calcium
Calcium is maximally absorbed in the ___, the absorption is favored at an acidic pH
Duodenum
Reference Value of Total Calcium
- Adult: 8.6-10 mg/dL
- Child: 8.8-10.8 mg/dL
Reference Value for Ionized Calcium
- Adult: 4.6-5.3 mg/dL
- Child: 4.8-5.5 mg/dL
Hypocalcemia can be a consequence of reduced plasma ___
Albumin
Increases intestinal absorption of Calcium
Increases reabsorption in the kidneys
Increases mobilization of calcium from bones
1,25-Dihydroxycholecalciferol (1,25-(OH)2D3)
Activated Vit D3
Conserves Calcium by increasing reabsorption in the kidneys
Increases the levels by mobilizing bone calcium
Activates process of bone resorption
Suppresses urinary loss of calcium
Stimulates conversion of inactive Vit D to active Vit D3 in kidneys
Parathyroid Hormone
Secreted by the parafollicular C cells of the thyroid gland
Inhibits PTH & Vitamin D3
Inhibits bone resorption
Promotes urinary excretion of Calcium
Calcitonin
End Product: Oxalic Acid
Purple
Calcium Methods
Clark Collip Precipitation
End: Chloranilic Acid
Purple
Calcium Methods
Ferro Ham Chloranilic Acid Precipitation
Dye: Arzeno III
Mg inhibitor: 8-hydroxyquinoline (chelator)
Calcium Methods
Ortho-Cresolphthalein Complexone Dyes
Reference Method for detection of Calcium levels:
Atomic Absorption Spectrophotometry
Other Methods for detecting Chloride levels:
EDTA Titration Method
Ion Selective Electrode (Liquid membrane)
Emission Flame Photometry
- Primary Hyperparathyroidism
- Cancer
- Acidosis
- Increased Vit D
- Multiple Myeloma
- Sarcoidosis
- Hyperthyroidism
- Milk-Alkali Syndrome
Hypercalcemia
CHIMPS
- Alkalosis
- Vitamin D deficiency
- Primary Hypoparathyroidism
- Acute Pancreatitis
- Hypomagnesemia
- Malabsorption Syndrome
- Renal Tubular Failure
Hypocalcemia
CHARD
Inversely related to Calcium
Maximally absorbed in the jejunum
Essential for the insulin-mediated entry of glucose into cells by a process involving phosphorylation of the glucose and co-entry of K+
Inorganic Phosphorus
Reference Value of Phosphorous
Adult: 2.7 - 4.5 mg/dL
Child: 4.5 - 5.5 mg/dL
Principal anion within cells
Organic Phosphate
Part of the blood buffer
Inorganic Phosphate
Decreases phosphate by renal excretion
Parathyroid Hormone
Inhibits bone resorption
Calcitonin
Increases phosphate renal absorption
Growth Hormone
Most commonly used method to measure serum inorganic phosphate
End: ammonium-molybdate complex (unstable)
Fiske Subbarow Method
Ammonium Molybdate Method
Most common reducing agent for Fiske Subbarow Method:
Pictol
Amino Naphthol Sulfonic Acid
- Hypoparathyroidism
- Renal Failure
- Lymphoblastic leukemia
- Hypervitaminosis D
Hyperphosphatemia
- Alcohol Abuse (MCC)
- Primary Hyperparathyroidism
- Avitaminosis D (No Vit D)
- Myxedema
Hypophosphatemia
Major cause of hypophosphatemia
Increase shift of phosphate into cells can deplete phosphate in the blood
Transcellular Shift
Intracellular cation second in abundance to potassium
4th most abundant cation in the body; enzyme activator
A Vasodilator and cause decrease uterine hyperactivity
Magnesium
Reference Value of Magnesium
1.2 - 2.1 mEq/L
Increases renal reabsorption of Magnesium
Increases intestinal absorption of Magnesium
Parathyroid Hormone
Increases renal excretion of Magnesium
Aldosterone & Thyroxine
- Diabetic coma
- Addison’s disease
- Chronic renal failure
- Increased intake of antacids, enemas & cathartics
Hypermagnesemia
- Acute renal failure
- Malnutrition
- Malabsorption Syndrome (Sprue)
- Chronic Alcoholism
- Severe diarrhea
Hypomagnesemia
End: Reddish-Violet complex
Magnesium Methods
Calmagite Method
End: Colored complex
Formazen Dye Method
Magnesium Method
End: Colored Complex
Magnesium Thymol Blue Method
Magnesium Method
Second most abundant anion in the ECF
Accounts for 90% of the total CO2 at physiologic pH
Buffers excess hydrogen ion by combining with acid
Bicarbonate
Specimen for Bicarbonate:
Blood anaerobically collected
Reference Value for Bicarbonate:
21-28 mEq/L
Difference between the unmeasured cations (Sodium & Potassium) and unmeasured anions (Chloride & Bicarbonate)
Anion Gap
Used to monitor recovery from diabetic ketoacidosis
Anion Gap (AG)
Anion Gap formula:
AG = Na - (Cl + HCO3)
AG = (Na + K) - (Cl + HCO3)
- Uremia/ Renal Failure
- Ketoacidosis
- Poisoning by Methanol, Ethanol, Ethylene glycol, or Salicylate
- Lactic Acidosis
- Hypernatremia
- Instrument Error
Increased Anion Gap
- Hypoalbuminemia
- Hypercalcemia
- Hyperlipidemia
- Elevated Myeloma proteins
Decreased Anion gap
Usually recognized in infancy or early childhood
Produce abnormally thick secretions of mucus, elevation of sweat electrolytes, increased organic and enzymatic constituents of saliva and overactivity of the ANS
Cystic Fibrosis
Mucoviscidosis
Diagnostic Test for Cystic Fibrosis
Sweat Test - Coulometry
Increased Na & Cl
Positive result for Cystic Fibrosis for Pilocarpine Iontophoresis
(> 65 mmol/L) of sweat electrolytes
Common metallic element important for the synthesis of hemoglobin
Prooxidant, contributing to lipid peroxidartion, atherosclerosis, DNA damage and carcinogenesis
Stored as Ferritin and Hemosiderin primarily in spleen, bone marrow and liver
Iron
Reference Value of Iron:
Male: 50-160 ug/dL
Female: 45-150 ug/dL
Refers to the amount of iron that could be bound by saturating transferrin and other minor-iron binding proteins present in the serum & plasma sample
Total Iron Binding Capacity (TIBC)
TIBC is a direct measure of the total number of functional ferrous ion-binding sites in ____
Transferrin
Reference Value of TIBC
Adult: 245-425 ug/dL
(>40 yrs old: 10-250 ug/dL)
Newborn & Child: 100-200 ug/dL
also known as: Transferrin saturation
Ratio of serum iron to TIBC
Percent Saturation
Normal Ratio of Percent Saturation
1:3
Lowest levels of Percent Saturation is seen in:
Iron Deficiency Anemia
Reference Value of % Saturation
20-50%