Electrolytes

Hyperkalemia

  • Mostly due tonimpaired renal excretion

  • Reduced aldosterone/response, renalnfailure

  • Cardiac Effects: decrease in resting membrane potential → cardiac arresr (10 mmol/L)

Pseudohyperkalemia

  • Hemolysis

  • Thrombocytosis

  • Prolonged tourniquet

  • Fisr clenching

  • Ice

Hypokalemia

  • Correlated: Hypomagnesemia = promote urinary K loss

  • Impaired Renal function - most common casuee

  • Diarrgea - most common cause of extrarenal loss

  • Vomiting

  • Cardiac effects: decreased cell excitability (increased RMP) → Arrythmia, Paralysis, Contract cessation

  • Alkalosis = K decreases by 0.4 mmol/L per 0.1 pH unit rise

Pseudohypokalemia

  • Leukocytosis

Chloride (Cl-)

  • Major extracellular anion

  • Vhief counterion of sodium in ECF

  • Function: maintains water balnce, osmotic pressure, blood volume, and electron neutrality

  • Only enxyme activator anyone of AMYLASE

  • Extrecreted in ruine and sweat

  • NV: 98-106 mEq/L

Specimen: serum, plasma, sweat

  • Hemolysis - decreased Cl

  • interferences: bromide, cyanide, cysteine

Method:

  1. Mercuric Titration (Schales and Schales)

    • indicator: diophenylcarbazone

    • end product: HgCl2 (Blue-Violet)

  2. Spectrophotometric Methods

    • mercuric thyo

  3. Colorimetric Amperometric Titratiob (Cotlove Chloridometer) = sweat (cystic fibrosis)

  4. ISE = tri-n-octylpropylammonium chloride decanol

    • most common metjod

Hypochloremia - metabolic alkalosis

  • Enters chloride shift - exchange of Cl and HCOs between plasma and RBC

  • Prolonged vomitting, aldosterone deficiency, salt-losing nephritis

Hyperchloremia

  • metabalic acidosis, renal tubular acidosis, diabetes insipidusn, prolonged diarrgea, salicylatr intoxification

Bicarbonaye (HCO-3)

  • Second most abundant anion in the ECF

  • Accoubts for 90% total CO2 AT PHYSIOLOGIC pH

  • Major component of thebbuffering system in the blood

  • Acid base imbalances

    • increased HCO3 metabolicnacidosis (compensated vybhyperventilation)

    • Decreased HCO3 metabolic alkalosis (compensated by CO2 retentionl

    • Diffuses out of cell in exchange for Cl

Specimen: anaerobically collected plasma/serum

Method:

  • ise - pCO2 electrode

  • Enzymatic - phosphoenolpyruvate carboxylase and dehydrogenase

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