By Brent Lee Lechner, DO MAJ, MC, USA 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

Case One Labs Urine Na+: <10 mEq/L OSM: 800 127 100 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.

Case Two Urine Na+: 60 mEq/L OSM: 250 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

Case Three Labs Urine Na+: <20 mEq/L OSM: 560 123 90 40 4.9 16 0.9

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

Case Four Labs Urine Na+: 77 mEq/L OSM: 280 126 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: No edema 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

Case Five labs Urine Na+: 65 mEq/L OSM: 780 122 96 5 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

Case Six Labs Urine Na+: 45 mEq/L OSM: 450 125 114 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 Weight U Na U 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