Electrolytes Flashcards by Peter John Gonzales

What are cations?

Positively charged ion

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What are electrolytes?

Charged ions found in extra/inter cellular and interstitial fluid

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Major cations in the body? (4)

Sodium, Potassium, Calcium and Magnesium

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What are anions?

Negatively charged ions

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What are the major anions found within the body? (6)

Chloride, phosphate, bicarbonate, sulfate, protein and organic acids

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clinically, what electrolytes are often measured?

Sodium, potassium, chloride and total carbon dioxide or bicarbonate

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What method is used to measure electrolytes such as sodium potassium chloride and bicarbonate?

Ion selective electrode

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Major cation of extra cellular fluid

Sodium

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Reference range for sodium

136-145 mmol/liter

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Changes in sodium results in a change in what

Plasma volume

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Largest contributor for plasma osmolality

Sodium

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Renal threshold value for sodium

110-130mmol/liter

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Condition when serum sodium is below 135mmol/liter

Hyponatremia

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Two types of hyponatremia

Delpletional and dilutional

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Depletional hyponatremia occurs in

Diarrhea, vomiting, severe burns/trauma hypoaldosteronism or Addison’s disease, diuretics

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What are the causes of dilutional hyponatremia

Over rehydration, syndrome of inappropriate anti diuretic hormone ( SIADH), congestive heart failure, cirrhosis and nephrotic syndrome

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Condition when serum sodium is above 150mmol/liter

Hypernatremia

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When does hypernatremia occur

Diarrhea, excessive sweating, diabetes insipidus, hyperaldosteronism, iv infusion, ingestion

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Major intracellular cation

Potassium

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Reference range for potassium

3.4-5.0

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Level of potassium when specimen is hemolysis

Increased

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Condition when potassium is below 3.0mmol/liter

Hypokalemia

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Hypokalemia occurs in

Decreased intake, hyperaldosteronism, diuretics, vomiting, diarrhea, laxative abuse, excess insulin

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Condition where potassium level is greater than 5.0 mmol/liter

Hyperkalemia

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What are the causes of hyperkalemia

Increased intake, hypoaldosteronism, metabolic acidosis, increased RBI lysis, leukemia, chemotherapy.

Major anion of the extracellular fluid

Chloride

Reference range for chloride

98-107 mmol/liter

Occurs when serum chloride is below 98

Hypochloremia

Occurs when chloride level is above 107mmol/liter

Hyperchloremia

Hypochloremia results from what conditions

Excessive vomiting, use of diuretics, burns aldosterone

Hyperchloremia results from what conditions

Prolonged diarrhea, renal tubular disorder, dehydration, excess loss of bicarbonate

Second largest anion fraction of the extracellular fluid

Bicarbonate

Reference range for bicarbonate

22-29mmol/liter

ctCO2 is comprised of what

HCO3, H2CO3, carbamino. Bound CO2, dissolved CO2

Clinical significance for low bicarbonate

Metabolic acidosis, diabetic ketoacidosis, salicylate toxicity

Clinical significance for high bicarbonate

Metabolic alkalosis, emphysema, vomiting

Formula used to demonstrate the electro neutrality in body fluids

Anion gap

Two formulas for computing anion gap

Na - (Cl + HCO3) = anion gap Na + K - ( Cl + HCO3) = anion gap

Reference range for anion gap if formula used does not contain potassium

7-16 mmol/liter

Reference range for anion gap if formula used contains potassium

10 - 20mmol/liter

Increased anion gap happens during ...

Lactic acidosis, ketoacidosis, hypernatremia, ingestion of methanol, salicylates

Decreased anion gap happens...

Hypoalbuminemia and hypercalcemia

What are the three forms of calcium found in plasma

Ionized, bound to protein, bound to anions

Decreased free calcium levels leads to muscle spasms termed as

Tetany

Serum calcium is regulated by 3 factors

Cholecalciferol or vitamin D Parathyroid hormone Calcitonin

What effect PTH has on serum calcium

Increases calcium

Effect of calcitonin towards serum calcium level

Decreased

What stimulates PTH

Low serum calcium levels

Another name for vitamin D

Cholecalciferol

What is the action of PTH in the bone

PTH activates osteoclasts to break down bone

Action of PTH in the kidneys

Enhances tubular reabsorption of calcium and stimulates the hydroxyl action of vitamin D to activ

How is cholecalciferol obtained?

Dietary intake and exposure to sunlight

What is the active form of cholecalciferol

1,25- dihydroxycholecalciferol

Effect of vitamin D in calcium

Increased absorption of calcium in the intestines

Which part produces calcitonin hormone

Parafollicular cells of the thyroid gland

Effect of calcitonin to vitamin D and parathyroid hormone

Inhibits PTH and vit D

3 methods for measuring calcium

ISE AAS Spectrophotometer in method ( ortho-cresolpthalein complex one, arsenazo III dye)

Method uses metallochromatic indicators that bind to calcium producing a color change

Spectrophotometric

In ISE analysis of calcium, why must the specimen be acidified first

To convert all the protein and anion bound calcium to ionized calcium

Interferences of spectrophotometric method of calcium include...

Hemolysis and icterus and lipemia

Can anticoagulants such as EDTA, oxtail ate and citrate be used for specimens that have calcium request

Interferences for ISE calcium analysis

Protein build up in electrode and in viro change in blood pH

Reference range for calcium

8. 6-10.3 mg/dl total calcium | 4. 6-5.3 mg/dl free calcium

3 factors that regulate phosphate levels

Kidneys excrete or reabsorb PTH increases renal excretion of phosphate Vitamin D intestinal absorption and renal reabsorption

Effect of PTH on phosphate level

Decrease

Effect cholecalciferol to phosphate level

Increase

Hyperphosphatemia is caused by what conditions?

Renal failure, hypoparathyroidism, neoplasticism diseases, lymphoblastic leukemia and intense exercise

Hypophophatemia is either caused by what conditions

Diabetic ketoacidosis, hyperparathyroidism, asthma, alcoholism, malabsorption syndrome

2 methods of measuring phosphate

Ammonium molydate + phosphate ions -> phosphomolybdate colorless complex read at 340 nm Aminonaphtholsulfonic acid to reduce the complex to form colored product at 600-700nm

Sources of error for phosphate measurement

Hemolysis, lipemia, icterus, anticoagulants

ReferencE range for phosphate

2.5 - 4.5

3 forms of magnesium in plasma

Free, bound to protein, complexed

Biologically active form of magnesium

Free

Percentage of. The 3 forms of magnesium found in plasma

55% free, 30% bound, 15% complexed

Percentage of 3 forms of calcium found in plasma

50% free, 30% bound 10% complexed

Effect of PTH to magnesium level

Increases reabsorption

Hyper magnesium is caused by what conditions

Renal failure and excess antacids

Hypomagnesium is caused by what conditions

GI disorder, renal disease, hyperparathyroidism others

Methods used to measure magnesium

Calmagite, methyl thymol blue, AAS

Measure free or ionized magnesium

ISE

Sources of error

Anticoagulants such as EDTA oxalate and citrate

Reference range for magnesium

1.7 - 2.4

Stored form of iron

Ferritin and hemosiderin

Transports iron

Transferrin

Serum iron exhibits diurnal variation, which part of the day is the value highest ( morning, noon, afternoon, nighttime)

Morning

Transferrin is increased in IDA, give a condition where it is decreased

Iron overload, hemochromatosis, severe infections

Reference range for transferrin

200-360

Ferritin reflects what part of iron supply and metab

Iron storage

True or false Ferritin is a sensitive and early indicator for iron deficiency disease

True

True or false Iron is increased in severe infections, iron overload, hemochromatosis

Itrue

Reference range for ferritin

20-250ng/ml for males 10-120ng/ml for females

Decreased serum iron indicates what conditions

IDA, malnutrition, blood loss and infection ( severe)

Increased iron is associated with what conditions

Iron overdose, sideroblastic anemia, viral hepatitis, hemochromatosis

Total iron content measures

Measure the serum iron bound to transferrin

TIBC measures what

Measure the iron bound to transferrin if all the binding sites on transferrin were occupied

Chromogen agent for total iron content

Bathophenanthroline or ferrosilicon

What is added to remove unbound Ferric in TIBC

MgCO3

Calculated value that represents the amount of iron that transferrin is capable of binding

Percent Transferrin saturation

Formula for percent transferrin saturation

% transferrin saturation = serum iron (ug/gl)/ TIBC(ug/dl) *100

Reference range for serum iron

45-160(ug/dl)

Reference range for TIBC

250-450 ug/dl

% saturation

15-55%