Fluids and electrolyte disorders





This chapter will review the pharmacotherapy for management of fluid and electrolyte disorders according to The Society for Endocrinology Endocrine Emergency Guidance and other expert panel.


General overview ( tables 21.1, 21.2, and 21.3 )




Table 21.1

Electrolyte Concentrations in the Extracellular and Intracellular Fluids and Daily Requirements

Data from Hall JE. Guyton and Hall Textbook of Medical Physiology. Philadelphia: Elsevier; 2016: 47-59 ( Chapter 4 ) and from National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Sodium and Potassium. Washington, DC: The National Academies Press; 2019. doi-org.easyaccess1.lib.cuhk.edu.hk/10.17226/25353 .



















































ELECTROLYTE NORMAL SERUM CONCENTRATION EXTRACELLULAR FLUID (mEq/L) INTRACELLULAR FLUID (mEq/L) DAILY REQUIREMENTS(g/day)
Sodium 135–145 mEq/L 142 10 1.2–1.5
Potassium 3.5–5.2 mEq/L 4 140 2.3–3.4
Chloride 95–105 mEq/L 103 4 1.8–2.3
Bicarbonate 24–32 mEq/L 28 10 N/A
Calcium 8.5–10.5 mg/dL 2.4 1–1.3
Magnesium 1.8–2.4 mg/dL 1.2 58 0.2–0.4
Phosphate 2.5–4.5 mg/dL 4 75 0.7–1.3

N/A , Not applicable.


Table 21.2

Electrolyte Composition of Intravenous Solutions











































































SOLUTIONS SODIUM (mEq/L) POTASSIUM (mEq/L) CHLORIDE (mEq/L) BICARBONATE (mEq/L) CALCIUM (mEq/L) MAGNESIUM (mEq/L) OSMOLALITY (mOsm/kg)
5% Dextrose 252
0.9% NaCl 154 154 308
0.45% NaCl 77 77 154
5% Dextrose-0.225% NaCl 34 34 320
3% NaCl 513 513 1026
Lactated ringer 130 4 109 28 2.7 274
PlasmaLyte, normosol 140 5 98 27 3 294

5% Dextrose, 5% Dextrose in water; NaCl , Sodium chloride


Table 21.3

Drugs that can induce Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Adapted from Liamis G, Milionis H, Elisaf M. A review of drug-induced hyponatremia. Am J Kidney Dis . 2008;52:144–153.







































DRUG MECHANISM



  • Tricyclic antidepressants (e.g., amitriptyline, imipramine)





  • Selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, paroxetine)




  • Increased hypothalamic production of antidiuretic hormone (ADH)




  • Monoamine oxidase inhibitors




  • Phenothiazines (e.g., thioridazine, trifluoperazine)




  • Butyrophenones (e.g., haloperidol)




  • Antiepileptics (e.g., carbamazepine, oxcarbazepine, valproic acid)




  • Antineoplastic agents (e.g., vincristine, vinblastine, cisplatin, carboplatin, cyclophosphamide, ifosfamide, methotrexate)




  • Opiates




  • Antiepileptics (e.g., carbamazepine, lamotrigine)




  • Potentiation of ADH




  • Antidiabetics (e.g., chlorpropamide, tolbutamide)




  • Antineoplastic (e.g., cyclophosphamide)




  • Nonsteroidal anti-inflammatory agents



Hypernatremia





  • Defined as a serum sodium level >145 mEq/L



  • Clinical manifestations: lethargy, irritability, restlessness, muscle spasticity, hyperreflexia, seizures, coma, and death



  • Gross estimation of free water deficit (Adrogue-Madias) = 0.6 × wt (kg) × [serum sodium/140 – 1]; use 0.5 × wt (kg) for women. The Adrogue-Madias equation often underestimates total body water deficit.



  • Dehydration: free water boluses using 200–300 mL q4–6h via feeding or suction tube. If no enteral route, intravenously (IV) as below



Management of acute hypernatremia (hypernatremia ≤48 h): Rare





  • Goal: decrease serum Na by 1–2 mEq/L per hour with max 10 mEq/L per 24 h



  • 5% dextrose (D5W) IV @3–6 mL/kg/h until serum Na 145 mEq/L; monitor serum Na q2–3h



  • Once serum Na 145 mEq/L, decrease D5W to 1 mL/kg/h until serum Na 140 mEq/L



  • Central diabetes insipidus: add desmopressin




    • Initial therapy: 5 to 10 mcg of the nasal spray every night (qhs)



    • 0.1 or 0.2 mg tablet qhs (may result in inadequate response)



    • 1 mcg subcutaneous q12h (if intranasal or oral route not feasible)



    • 2 mcg IV q12h (if inadequate response to subcutaneous)




Management of chronic hypernatremia (hypernatremia >48 h): Common








    • D5W IV @1.35 mL/h × weight (kg) to lower serum Na by max 10 mEq/L per 24 h



    • If concurrent hypovolemia: 0.225% NaCl @1.8 mL/kg/h



    • If concurrent hypovolemia and hypokalemia: 0.225% NaCl with KCl 40 meq/L @2.7 mL/kg/h



    • Monitor serum sodium concentration q4–6h until goal achieved then q12–24h




  • If hypernatremia due to correction of severe hyperglycemia and hypovolemia (e.g., diabetic ketoacidosis, hyperosmolar hyperglycemic state): 0.45% NaCl 6–12 mL/kg/h to lower serum Na by max 10 mEq/L per 24 h



Hyponatremia





  • Defined as a serum sodium level <135 mEq/L



  • Clinical manifestations: lethargy, disorientation, restlessness, muscle weakness, depressed reflexes, seizures, coma, and death



Treatment of acute or severe hyponatremia ( table 21.4 )



Feb 28, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Fluids and electrolyte disorders
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