Critical Fluid and Electrolyte Abnormalities in Clinical Practice CCF Board Review ▲ 2011 JOSEPH V. NALLY, JR., M.D. Department Nephrology & Hypertension

Glickman Urological & Kidney Institute

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Clinical Hyponatremia: Principles • Normal plasma sodium 135- 145 mEq/l • Normal plasma osmolality 280-290 mOsm/kg • Alterations of plasma sodium concentration are primarily disorders of water homeostasis, not sodium homeostasis. • Osmolality can be measured or estimated Osm= 2[Na] + Glucose(mg/dl)/18 + BUN (mg/dl)/2.8 OR

Osm= 2[Na] + 10 S:\SLIDES\2010\Nlly\2011 CCF-IRIM-CritFluid+ElecAbn-ClinPract.ppt

Nephron Schematic

100% remaining

Sodium chloride reabsorption

8% remaining

33% remaining

Griebisch G & Windhager E. Transport of sodium and chloride, Chapter 34 In: Boron WF, Boulpaep EL (editors), Medical Physiology. Philadelphia:Saunders, 2003; p. 778. S:\SLIDES\2010\Nlly\2011 CCF-IRIM-CritFluid+ElecAbn-ClinPract.ppt

3% remaining

Osmotic Stimulation of ADH Thirst

Plasma ADH, pg/mL

12 NORMAL 8

4

0 270 280 290 300 Plasma osmolality, mosmol/kg S:\SLIDES\2010\Nlly\2011 CCF-IRIM-CritFluid+ElecAbn-ClinPract.ppt

310

Non-osmotic Stimulation of ADH 50 Plasma ADH, pg/mL

45 40 35 30 25 20 15 10 5 0

0

5

10

15

20

Blood volume depletion, % Hypotension / Decr Effective Circ Volume S:\SLIDES\2010\Nlly\2011 CCF-IRIM-CritFluid+ElecAbn-ClinPract.ppt

V2 Receptor (V2R) AQP2

Microtubule Dynein

VAMP-2

V2 Receptor

Dynactin

P P

Syntaxin-4

Protein Kinase A

AVP

G

Phosphodiesterase

G-prot.

cAMP

Myosin-1

A.C.

NSF Exocytosis ATP

P Nucleus

Recycling

CREB-P CRE AP1

Endocytosis

G Ep Receptor

Synthesis Other Receptors

Degradation

Urinary excretion S:\SLIDES\2010\Nlly\2011 CCF-IRIM-CritFluid+ElecAbn-ClinPract.ppt

PGE2

DIFFERENTIAL DIAGNOSIS OF HYPONATREMIA 1. Check Plasma Osmolality

Hyponatremia Check plasma osmolality

Low

Normal

Check Urine osmolality

PSEUDOHYPONATREMIA

Hyperproteinemia Hyperlipidemia >100 mOsm Various causes hypotonic hyponatremia

20 mEq/L