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Hyponatremia. By Brent Lee Lechner, DO MAJ, MC, USA. Basic Concepts in Sodium Handling. Why is the sodium low? Too much water Too little salt What aids in this decision? Patient volume status clinically Weight Urine Na + Urine Osm. Basic Concepts in Sodium Handling.
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Hyponatremia By Brent Lee Lechner, DO MAJ, MC, USA
Basic Concepts in Sodium Handling • Why is the sodium low? • Too much water • Too little salt • What aids in this decision? • Patient volume status clinically • Weight • Urine Na+ • Urine Osm
Basic Concepts in Sodium Handling Kidney preserves volume with highest priority!
Basic Concepts in Urine Evaluation • U Na+ reflects renal perfusion independent of S Na+: • Low U Na+ (<10 to 20 mEq/L) • Renal Perfusion is decreased • High U Na+ (>20 mEq/L) • Renal Perfusion is increased or normal • Defect in tubule reabsorption • If U Na+ elevated in clinical circumstance when renal blood flow is expected : Identify renal reabsorption defective.
Basic Concepts in Urine Evaluation • U OSM reflects H20 removal from tubule fluid: • Normal U OSM • (200-1200 mOsm/L) • SG in urine 1.010 = U OSM 300 mOm/L
Basic Concepts in Urine Evaluation • ADH Secretion • U OSM > 1.5 X S OSM: ADH must be acting on collecting duct – irrespective of S OSM • Physiologic stimuli for ADH release • Increase S OSM/ S Na+ • Decrease intravascular volume • If U OSM/S OSM > 1.5 without increased S OSM or decreased intravascular volume: • ADH secretion is non-physiologic – irrespective of urine volume.
Case One • 14 month infant • Four day history of nausea/vomiting/diarrhea and fever. • Decreased urine output • 3 lb weight loss
Urine Na+: <10 mEq/L OSM: 800 Case One Labs 127 100 43 3.0 16 0.5
Question Set One • What is the diagnosis? • Explain how you reached this diagnosis? • Does the patient seem to have more vomiting or diarrhea?
Bonus Question • What “state” was the bar in which Maverick and Goose frequently attended and sang “Great Balls of Fire” in Fighter Town, USA? • Movie: TOP GUN
Case Two • 14 month old • Patient in case one tried oral rehydration • Waited 10 hours • Nausea/Vomiting/ diarrhea persisted • Weight is decreased by 4 lbs.
Urine Na+: 60 mEq/L OSM: 250 Case Two 65 125 92 6.5 9.4 1.2
Question Set Two • The patient appears even more volume depleted but renal perfusion appears adequate with urine Na+ at 60 mEq/L. Is renal perfusion adequate? • Explain low bicarbonate.
Bonus Question • In the movie “A scent of a woman,” how did the infantry colonel played by Al Pacino lose his sight?
Case Three • Five year old male • Periorbital Edema and ankle swelling • Weight gain 5 lb in 4 days • Recent URI • Decreased urine output • Blood Pressure: 92/54
Urine Na+: <20 mEq/L OSM: 560 Case Three Labs 123 90 40 0.9 4.9 16
Case Three Question • What is the child’s diagnosis? • What one lab test would confirm your answer to the above question? • How do you fix the serum Na+?
Bonus Question • In the movie “An officer and gentleman,” what does Mayo’s (Richard Gere) friend (the guy from Oklahoma) tell his “girlfriend” (the girl faking the pregnancy) job is waiting at home?
Case Four • 17 year old Female • Cheerleader • Weight loss: 4 lbs in past week • Lives with Grandmother and Parents • Distorted body image
Urine Na+: 77 mEq/L OSM: 280 Case Four Labs 126 88 34 2.7 32.5 0.7
Case Four Questions • What is differential diagnosis? • What can you test in the urine to help determine the diagnosis?
Bonus Question • In the movie “A Few Good Men,” what law school did Tom Cruise’s character graduate from?
Case Five • 14 year old male with ALL • Chemotherapy: • Vincristine, Cytoxan, and Decadron • 1 and ½ Maintenance fluid : ½ NS for 3 days • No edema • Slight weight gain: 4-7 lbs in 7 days
Urine Na+: 65 mEq/L OSM: 780 Case Five labs 122 5 96 3.0 20.5 0.4
Case Five Questions • Diagnosis? • Change to NS, Right? • What is the treatment?
Bonus Question • What is the occuption and home state of Tom Hanks character in the movie “Saving Private Ryan,” prior to him entering the U.S. Army?
Case Six • 15 year old female • Polyuria • Thirsty all the time • Decreased weight • Some increased respiratory rate
Urine Na+: 45 mEq/L OSM: 450 Case Six Labs 125 114 40 450 6.8 12.6 1.3
Case Six Questions • What is the diagnosis? • What is driving the urine output and loss of Na+ in the urine?
Bonus Question • At the end of basic training in the movie “Full Metal Jacket,” what job in the U.S. Marine Corps does “Joker” obtain?
Clinical Utilization of U Na and U OSM Increased WeightU NaU OSM Decreased Weight Hypoalbuminema <10 >500 Dehydration/Volume Depletion Nephrosis/Cirrhosis Cystic Fibrosis AGN Acute Volume expansion <10 <300 Diabetes Insipidus Water Intoxication Excess IV Fluid Acute Renal Failure >50 <= 300 Adrenal Insufficiency Sepsis,Shock, Nephrotoxin Salt-losing Nephropathy Interstitial Nephritis/Cystic Dz/ Urinary Tract Obstruction Non-Physiologic ADH >50 >500 DKA Osmotic Diuretics