DISTURBANE IN SODIUMAND WATER BALANCE

Dr Ayman Seddik ,MD

Ass.Prof.Nephrology Ain Shams University

Consultant nephrologist

Solute Composition of Body Water

• Predominant solutes in ECF: Sodium (Na+) Chloride (Cl−)

Bicarbonate (HCO3−) • Predominant solutes in ICF:

Potassium (K+) Protein− Phosphate−

Osmolality

•Posm=2×plasma Na+ +

Glucose/18 + BUN/2.8

Osmolality • Normal ECF osmolality: 280-290mOsm/kgH2O

• ECF and ICF are in osmotic equilibrium, at

steady state

• Vasopressin (antidiuretic hormone (ADH)

-osmotic stumuli

-nonosmotic stumuli: HF, Cirrhosis, vomiting, postoperative pain, pregnancy

Hyponatremia

• Serum Na <135 mEq/L

European Society of Intensive Care Medicine (ESICM) European Society of Endocrinology(ESE) European Renal Association – European Dialysis and Transplant Association (ERA–EDTA)

Hyponatremia

• Serum Na <135 mEq/L

Hyponatremia is a disorder of water balance

Dısorders of water and sodium balance CONTENT VERSUS SERUM CONC OF NA

• Hyponatremia (too much water)

• Hypernatremia (too little water)

• Hypovolemia (too little sodium, the main

extracellular solute)

• Edema (too much sodium with associated

water retention)

Hyponatremia

• almost always due to the oral or intravenous

intake of water that cannot be completely

excreted

• impaired water excretion that is most often

due to an inability to suppress the release of

antidiuretic hormone (ADH) or to advanced

renal failure

Diagnosis

• Volume status and serum osmolality are

essential to determine etiology

• Hyponatremia usually reflects excess water

retention relative to sodium rather than sodium

deficiency, the sodium concentration is not a

measure of total body sodium

• Hypotonic fluids commonly cause hyponatremia

in hospitalized patients

Symptoms and Sing of Hyponatremia

• symptoms depends on severity and acuity hyponatremia

• the symptoms reflect neurologic dysfunction induced by cerebral edema and possible adaptive

responses of brain cels to osmotic swelling

• Nausea, malaise, headache, lethargy, seizures, coma, respiratory arrest

• the physical examination should help categorize the patient's volume status into hypovolemia,

euvolemia, or hypervolemia.

Classification of symptoms of hyponatraemia

Clinical practice guideline on diagnosis and treatment of hyponatraemia; Nephrol Dial Transplant (2014) 0: 1–39

Adaptation of the brain to hypotonicity

Adrogue HJ & Madias NE. Hyponatremia. NEJM; 2000 342 1581–1589

Complications of hyponatraemia

Hyponatraemia with severe symptoms

PRACTICAL POINT learned from Dr Railey in DH • NORMAL SALINE 153 MMOL/DL

• 3.8% SALINE 531 MMOL /DL

• 200ML 3.8% HYPERTONIC

• 200*531/1000= 106 MMOL NA

• 800ML SODIUM CHLORIDE =122 MMOL NA

• 1 LITRE 228 MMOL SODIUM

• SMOOTH CORRECTION …. FOLLOW UP EVERY 6 HOURS …. STOP WHEN NA INCREASE > 8 MMOL /DAY …… NORMAL SALINE CONTINUE

7.2. Hyponatraemia with moderately severe symptoms

7.3. Acute hyponatraemia without severe or moderately severe symptoms

7.4. Chronic hyponatraemia without severe or moderately severe symptoms

7.4. Chronic hyponatraemia without severe or moderately severe symptoms

7.4. Chronic hyponatraemia without severe or moderately severe symptoms

Na+ deficit ≈

body weight X 0.6 X

(desired plasma Na+ concentration –

plasma Na+ concentration)

1mg/dl/ h

10-12mg/dl /24h

Hypernatremia

• Serum Na>145 mEq/L

Symptoms and Sings of Hypernatremia

• Dehydrated patient → orthostatic hypotension and oliguria

• Rise in plasma Na and osmolality →water movement out of the brain →rupture of the cerebral veins →focal intracerebral and subarachnoidal

hemorrages→possible ireversible neurologic damage

• Lethargy, weaknees, irritability, twitching,

seuzures, coma • Osmotic demyelination (uncommon)

Laboratory Findings

• Urine osmolality > 400 mosm/kg → renal

water-conserving ability is functioning (hypotonic

fluid losses from excessive sweating, the respiratory tract, or bowel movements and lactulose)

• Urine osmolality < 250 mosm/kg →

characteristic of DI

-Central DI: inadequate ADH release

-Nephrogenic DI: renal insensitivity to ADH (lithium, demeclocycline, relief of urinary obstruction, interstitial nephritis, hypercalcemia, and hypokalemia)

• Water deficit ≈

body weight X 0.6 X

(plasma Na concentration/

desired plasma Na concentration) - 1