Hyponatremia

Lecture By:
Dr.Mohammed Saber
ICU physician, Meeqat General Hospital, Madinah,KSA

1. Hyponatremia In the ER & ICU Dr. Mohamed saber icu resident A practical approach

2. At the end of this lecture You will be able to: Identify the cause of true hyponatremia Calculate the sodium deficit Correct hyponatremia using 3% or 0.9% Salines

3. Basics you should Know Normal Serum Na = 135-145 mEq /L Mild Hyponatremia = 130-135 mEq /L Moderate Hyponatremia = 125-130 mEq /L Severe Hyponatremia = <125 mEq /L Normal Plasma Osmolality = 280-290 mOsmol /kg

4. Hyponatremia Measure Sr. Osmolality Normal 280-290 Low <280 High >290 Hyperosmolar Hyponatremia Hyperglycemia Hypertonic infusions ( e.g. Mannitol) Assess volume status Pseudohyponatremia 1. Hyperlipidemia 2. Hyperparaproteinemia 2 X [Na] + [glucose mg/dl]/18 + [BUN mg/dl]/2.8 Ex.: Na 125, glucose 110, BUN 11.2 = 2x125 + 110/18 + 11.2/2.8 = 250 + 6 + 4 = 260

5. Assess volume status Euvolemic SIADH (Urine Osm. >100 mOsm/kg) Psychogenic Polydepsia (Urine Osm. <100 mOsm/kg) Beer Potomania Hypothyroidism Cortisol deficiency Hypervolemic

6. What is SIADH and What causes it ? Neuropsychiatric disorders such as Meningitis, Encephalitis, Acute psychosis, CVA , Head trauma Chest : Pneumonia , T.B, Acute Respiratory failure , Positive pressure ventilation Malignancy : Small Cell lung cancer Stress : Physical/Emotional Drugs : NSAIDs , Aminophylline , Carbamazepine ( Tegretol ), Antipsychotics like Haloperidol, Opioids

7. Hypovolemic Assess volume status Euvolemic SIADH (Urine Osm. >100 mOsm/kg) Psychogenic Polydepsia (Urine Osm. <100 mOsm/kg) Hypothyroidism Cortisol deficiency Amphetamine use Beer p otomania syndrome Hypervolemic

8. >20 mEq/L (Renal losses) Recent diuretics (especially thiazides) Adrenal insufficiency Salt-losing nephropathy Cerebral salt wasting Ketonuria <20 mEq/L (Extra-Renal losses) Vomiting, Diarrhea, Fistulas, Bowel obstruction Burns, Sweating Pancreatitis, Peritonitis Check Urine Na concentration Hypovolemic Hypervolemic Check Urine Na concentration <20 mEq/L CHF Decompensated Cirrhosis Nephrotic syndrome Hypoalbuminemia >20 mEq/L Acute or Chronic renal failure

9. Meet your patient Your patient may be a case of: CVA Pneumonia or Acute Respiratory failure Psychiatric on Antipsychotics COPD on theophylline Patient may be symptomatic: Dizzy, Headache, Seizures or Decreased GCS HF on diuretics Severe GE DKA or HHS Hepatic patient

10. Save your patient Step 1: ABC Assess the airway for possible Intubation and Ventilation Step 2: IV line for resuscitation Step 3: Focused Hx Step 4: Identify the Cause Step 5: Other Investigations: Full biochemistry, ABG, Sr. TSH and Cortisol Below Eight intubate

11. Step 6: Rate of Correction Asymptomatic and chronic (>2 days): No immediate correction is needed if mild hyponatremia Treat the cause Water restriction Correct at a rate not greater than 0.5 mEq/ hr Or 12 mEq/L/day Symptomatic Or Acute (<2 days): Rate of 1-2 mEq/L for an initial few hrs or till seizures subside Do not exceed 12 mEq/L/day

12. Step 7: Calculate the sodium deficit Na deficit = Total body water (TBW) X [Target Sr. Na – Measured Sr. Na] TBW = Adult male and children: 0.6 X Body Wt Adult Female: 0.5 Elderly male: 0.5 Elderly Female: 0.45 Ex.: 60-kg Female, Sr. Na 115 with a goal of increasing Na by 8 mEq in the First 24 hrs Sodium deficit = (60x0.5) x (123-115) = 240 mEq

13. How will we correct? 3% Hypertonic saline Contains approximately 500 mEq of Sodium per Liter or 0.5mEq per 1mL So 480 ml of 3% will be needed to correct this 240 mEq of Sodium This means 20ml/ hr for 24 hrs 0.9% NS contains 154 mEq of Sodium per Liter So 1550 ml will be needed to raise this 240 mEq This means 65ml/ hr

14. ABC is always First Detect True Hyponatremia Calculate Na deficit Use 3% or 0.9% NS Recheck Na every 2 hrs for Rapid correction or every 6 hrs for slow correction Treat your patient not the Labs Recap

15. Thank you