Electrolytes Flashcards
Equal no. of cations and anions
Electroneutrality
Balance of charges
Electroneutrality
Average water content of the human body
40-75%
1/3 of total body water
ECF
2/3 of total body water
ICF
Normal plasma
[?] water(Plasma: [?] > Whole blood)
[?] solutes: (Increased in dehydration)
93%; 13%
7%
7% solutes:
-Proteins
-Glucose
-NPN
-Lipids
-Ions
Excretion of 10-20L H2O everyday
Vasopressin deficiency
Volume and Osmotic regulation
Sodium Potassium Chloride
Electrolytes
EC =
IC =
Na+ > Cl- > HCO3- > Ca2+(5th) > iPO4
K+ > Mg2+(4th)
Myocardial rhythm and contractility
Potassium
Neuromuscular excitability
Calcium
Magnesium
Cofactors (enzyme)
Calcium
Magnesium (CK)
Zinc
Chloride (AMS)
Potassium
ATPase ion pump
Magnesium
Production and use of ATP from glucose
Magnesium
Phosphate
Production and use of ATP from glucose
Magnesium
Phosphate
Acid-base balance
Bicarbonate
Replication of DNA and translation of mRNA
Magnesium
Major contributor of osmolality (92%, together w/ Chloride and Bicarbonate)
Sodium
↑100 mg/dL glucose =
↓1.6 mmol/L sodium
Aldosterone
Sodium
Potassium = Magnesium
↑ Sodium
↓ Potassium = ↓ Magnesium
Atrial natriuretic factor
Sodium
↓ Sodium
Excess water loss
Hypernatremia
Decreased water intake
Hypernatremia
Hyperaldosteronism (Conn’s disease)
Hypernatremia
Hypothalamic disease (Chronic hypernatremia)
Hypernatremia
Renal failure
Hyponatremia
SIADH (increased water retention)
Hyponatremia
Marked hemolysis (dilutional effect)
Hyponatremia
<125 mmol/L = severe neuropsychiatric symptoms
Hyponatremia
Major defense against hyperosmolality and hypernatremia
Thirst
= severe thirst
= Moderate deficit of water
= Severe water deficit
1-2% water deficit
150-160 mEq/L Na+
> 165 mEq/L Na+
Pseudohyponatremia (artifactual)
Hyperlipidemia (turbidity)
Hyperproteinemia
Methods (Na+)
- FEP
- AAS
- ISE
- Colorimetry =
= Glass aluminum silicate
= Albanese Lein
- ISE
- Colorimetry
Concentration in RBC is 105 mmol/L
Potassium
Reciprocal relationship with H+
Potassium
0.5% hemolysis =
Gross hemolysis =
↑ 0.5 mmol/L
↑ 30%
Serum K+ > Plasma K+ by 0.1-0.7 mmol/L because of
platelets (clot)
in muscle activity
↑ 10-20%
= mild to moderate exercise
↑ 0.3-1.2 mmol/L
= vigorous exercise; fist clenching
↑ 2-3 mmol/L
Decreased resting membrane potential → incr. contractility → lack of muscle excitability
Hyperkalemia
Decreased renal excretion (Dehydration, renal failure, Addison’s disease)
Hyperkalemia
Acidosis (DM)
Hyperkalemia
Muscle injury
Hyperkalemia
Spironolactone
Hyperkalemia
Increased resting membrane potential → arrhythmia
Hypokalemia
Leads to hypomagnesemia
Hypokalemia
Vomiting
Hypokalemia
Diuretics
Hypokalemia
Cushing’s syndrome
Hypokalemia
Alkalosis
Hypokalemia
Insulin overdose
Hypokalemia
Renal tubular acidosis
Hyperchloremia
Metabolic acidosis
Hyperchloremia
Diabetes insipidus (Dehydration)
Hyperchloremia
Prolonged diarrhea
Hyperchloremia
Prolonged vomiting (↓ HCl)
Hypochloremia
Aldosterone deficiency (↓ Na+ = ↓ Cl- = ↑ K+)
Hypochloremia
Metabolic alkalosis (↑ HCO3- = ↓ Cl-)
Hypochloremia
Marked hemolysis (dilutional effect)
Hypochloremia
Acidosis (Ca2+: from Bones → Blood)
Hypercalcemia
Cancer
Hypercalcemia
Hyperthyroidism
Hypercalcemia
Milk-alkali syndrome
Hypercalcemia
Tetany
Hypocalcemia
Alkalosis (Ca2+: from Blood → Bones)
Hypocalcemia
Acute pancreatitis (Ca2+: binds to damage pancreatic tissues)
Hypocalcemia
Hypoparathyroidism
Hyperphosphatemia
Renal failure
Hyperphosphatemia
Hypervitaminosis D
Hyperphosphatemia
Alcohol abuse = most common cause
Hypophosphatemia
Primary hyperparathyroidism
Hypophosphatemia
Avitaminosis D (Rickets, Osteomalacia)
Hypophosphatemia
Addison’s disease
Hypermagnesemia
Chronic renal failure
Hypermagnesemia
Acute renal failure
Hypomagnesemia
Chronic alcoholism
Hypomagnesemia
Uremia/renal failure
Increased AG
Ketoacidosis
Increased AG
Lactic acidosis
Increased AG
Methanol poisoning
Increased AG
Ethanol poisoning
Increased AG
Ethylene glycol poisoning
Increased AG
Salicylate poisoning
Increased AG
Hypoalbuminemia
Decreased AG
Hypercalcemia
Decreased AG
Hyperlipidemia
Decreased AG
Multiple myeloma
Decreased AG
Hemochromatosis
Increased iron
Viral hepatitis
Increased iron
Non-IDA
Increased iron
IDA
Decreased iron
Malnutrition
Decreased iron
Chronic infection
Decreased iron
pH and K+
↓ pH by 0.1 =
↑ K+ by 0.2-1.7 mmol/L
Methods (K+)
= preferred
Lithium heparin plasma
Methods (K+)
- FEP
- AAS
- ISE = Valinomycin gel
- Colorimetry = Lockhead and Purcell
- ISE =
- Colorimetry =
Valinomycin gel
Lockhead and Purcell
Chief counter ion of sodium in ECF
Chloride
Chloride methods measure
bromide and iodide
↓ Cl- =
↓ HCO3-
Methods (Cl-)
- Schales and Schales
- Whiterhorn Titration method
- Ferric perchlorate
- Cotlove chloridometer
- ISE -Ion exchange membrane
- Schales and Schales
-Mercurimetric titration
-Diphenylcarbazone
- Schales and Schales
-Excess Hg++
- Schales and Schales
-(+) Blue violet
- Schales and Schales
-Mercuric thiocyanate
- Whiterhorn Titration method
-Reddish complex
- Whiterhorn Titration method
-Coulometric amperometric titration
- Cotlove chloridometer
-Excess Ag++
- Cotlove chloridometer
-Ion exchange membrane
- ISE
-Tri-n-octylpropylammonium chloride decanol
- ISE
Calcium
99% =
1% =
Bones
ECF
Absorbed in the duodenum
Calcium
Absorption is favored at an acidic pH
Calcium
3 Forms of Calcium
= Free/Ionized/Unbound/Active Calcium
= Protein-bound (Albumin)
= Complexed with anions
50%
40%
10%
↑ Ca2+ = ↑ absorption (intestine) and reabsorption (kidney)
Vitamin D3
↑ Ca2+ = ↑ resorption (bone) and reabsorption (kidney)
PTH
↓ Ca2+ = ↑ urinary excretion (major net loss of calcium)
Calcitonin
Practical considerations (Ca2+)
= specimen of choice
Serum
↓ Albumin (1g/dL) =
↓ Ca2+ (0.8 mg/dL)
Low PTH
Primary hypocalcemia
Parathyroid gland disease
Primary hypocalcemia
High PTH
Secondary hypocalcemia
Renal failure (↑ excretion)
Secondary hypocalcemia
Methods (Ca2+)
- Clark Collip precipitation method
- Ferro Ham Chloranilic acid precipitation method
- Colorimetric
- EDTA titration method (Bachra, Dawer and Sobel)
- AAS
- ISE
- FEP
-(+) Oxalic acid -Renal calculi
- Clark Collip precipitation method
-(+)Chloranilic acid
- Ferro Ham Chloranilic acid precipitation method
= Ortho-Cresolphthalein complexone dyes
-Dye: Arzeno III -8-hydroxyquinoline
- Colorimetric
= chelates (inhibits) Mg2+
Arzeno III -8-hydroxyquinoline
- AAS =
- ISE =
Reference method
Liquid membrane
Inorganic Phosphorus
85% =
15% =
Bones
ECF (iPO4)
Maximally absorbed in the jejunum (Ca2+: duodenum)
Inorganic Phosphorus
Trancellular shift: Once absorbed inside cells, it no longer comes out = used for energy production
Inorganic Phosphorus
Dirunal variation: ↑ late morning, ↓ evening
Inorganic Phosphorus
= principal anion within cells
Organic phosphate
= part of the blood buffer (Measured in the clin.lab.)
Inorganic phosphate
3 Forms of Inorganic Phosphorus
= Free
= Complexed with ions
= Protein-bound
55%
35%
10%
↓ PO4 = ↑ Ca2+
PTH
↑ PO4 = ↓ Ca2+
Calcitonin
↑ PO4 (renal reabsorption)
Growth hormone
Fasting is required (Nonfasting: ↓)
PO4
Methods (iPO4) Most accurate:
unreduced phosphomolybdate formation (340nm)
Methods (iPO4)
- Fiske Subbarow Method (Ammonium molybdate method)
-Reducing agents: Pictol, Elon, Senidine, Ascorbic acid
- Fiske Subbarow Method (Ammonium molybdate method)
-(+) Phosphomolybdenum blue
Fiske Subbarow Method (Ammonium molybdate method)
Magnesium
53% =
46% =
1% =
Bones
Muscles and soft tissues
Serum and RBC
Vasodilator
Magnesium
3 Forms of Magnesium
55% =
30% =
10% =
Free/Ionized/Physiologically active
Protein-bound
Complexed with ions
↑ Mg2+ = ↑ Ca2+ = ↓ PO4
PTH
↓ Mg2+ = ↓ K+ = ↑ Na+
Aldosterone (& Thyroxine)
Methods (Mg2+)
- Calmagite
- Formazen dye method
- Magnesium Thymol blue method
- AAS = reference method
- Dye-lake Method
-(+) Reddish-violet complex
-(+) Colored complex
-(+) Colored complex
-Titan Yellow dye (Clayton Yellow or Thiazole yellow)
- Calmagite
- Formazen dye method
- Magnesium Thymol blue method
- Dye-lake Method
90% of the total CO2
Bicarbonate
HCO3- diffuses out of the cell in exchange for Cl- to maintain ionic charge neutrality w/in the cell
Chloride shift
Difference between unmeasured anions and unmeasured cations
Anion Gap
QC for ISE
Anion Gap
Cystic Fibrosis (Mucoviscidosis) Defective gene:
Cystic fibrosis transmembranous conductance regulator (Chromosome 7)
Miconeum ileus (Infants) ; Foul-smelling stool ; URT infection
Cystic Fibrosis (Mucoviscidosis)
↑ Na+ and Cl-
Cystic Fibrosis (Mucoviscidosis)
Sweat inducer
Pilocarpine
Reference method (Sweat sodium and chloride)
Gibson & Cooke pilocarpine iontophoresis
Prooxidant
Iron
Iron
= Total body iron
= Hgb
= Transferrin and Ferritin
3-5g
Ferrous
Ferric
Methods (Iron)
- Colorimetric = HCl and Ferrozine
-(+) Blue color - Anodic stripping voltammetry
UIBC + Serum Iron
TIBC
Increased: IDA, hepatitis, iron-supplemented pregnancy
TIBC
Decreased: Non-IDA, nephrosis
TIBC
Measure of reserve iron binding capacity of transferrin
UIBC
Index of iron storage
% Transferrin Saturation
Increased: Iron overdose, hemochromatosis, sideroblastic anemia
% Transferrin Saturation
Decreased: IDA (lowest), malignancy, chronic infection
% Transferrin Saturation
TIBC (μg/dL) x 0.70 = mg/dL
Transferrin
Sodium 1/α Potassium
Potassium 1/α Hydrogen ion
Potassium α Magnesium
Magnesium α Calcium
Calcium 1/α Inorganic phosphate
Chloride 1/α Bicarbonate
