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Na /K Disorders

Na /K Disorders. Dr Mojgan Mortazavi. SODIUM. Hyponatremia. Hyponatremia. Hyponatremia defined as a Na+ <135meq/l that usually reflects hypoosmolality . Low plasma osmolality causes water movement into the cells and then cellular overhydration particularly in brain cells.

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Na /K Disorders

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  1. Na /K Disorders Dr MojganMortazavi

  2. SODIUM

  3. Hyponatremia

  4. Hyponatremia • Hyponatremia defined as a Na+ <135meq/l that usually reflects hypoosmolality. • Low plasma osmolality causes water movement into the cells and then cellular overhydration particularly in brain cells

  5. Symptoms of hyponatremia • The changes induced by acute hyponatremia (developing over 1-3 days) may result in permanent neurological damage and are primarily duo to cerebral overhydration • Nausea and malaise as the plasma Na+ falls acutely below 125 meq/l • Headache, lethargy, and obtundation may appear in Na+ between 115-120

  6. Symptoms of hyponatremia….. • The more sever changes of seizures and coma are not seen until the plasma Na+ is less than 110-115 meq/l • Women particularly premenopausal women ,appear to be at much greater risk of developing sever neurologic symptoms and of irreversible neurologic damage than men that may be related to differences in cerebral metabolism and sex hormones.

  7. Treatment • There are two basic principles involved in the treatment of hyponatremia: 1-rasing the plasma Na+ at a safe rate 2-treating the underlying cause

  8. Treatment with Nacl • True volume depletion • Diuretics • Adrenal insufficiency

  9. Treatment with H2O restriction • SIADH • Edematous state • Renal failure • Primary polydipsia

  10. The risk factors for developing osmotic demyelination • 1-More than a 12 meq/l elevation in Na+ in the first day • 2-Over correction of the Na+ to above 140 meq/l within the first 2 days • 3-Hypoxic or anoxic episodes prior to therapy

  11. TREATMENT OF SIADH • Acute: 1-water restriction 2-hypertonic saline or Nacl tablets 3-loop diuretics • Chronic: 1-water restriction 2-high salt ,high-protein diet 3-loop diuretic 4-demeclocycline ,lithium

  12. TREATMENT OF SIADH • Asypmtomatic or Chronic • SIADH • Water restriction • 0.5-1 liter/day • Salt tablets • Demeclocycline • Inhibits the effects of ADH • Onset of action may require up to one week

  13. Treatment • Goal: • raise Na by <10 meq/L in the 1st 24 hours • raise Na by <18 meq/L in the 1st 48 hours

  14. Central Pontine Myelinosis • Correction of Na too FAST • more common w/alcoholism, malnutrition, chronic illness • Symptoms: flaccid paralysis, dysarthria, dysphagia • Evolve over days – weeks • May extend dorsally  Sensory Tracts • locked-in syndrome • Turn off ADH & prompt diuresis  Sudden & Dramatic Inc serum Na

  15. Hyponatremia • Example: • a 60 kg women with a plasma sodium of 110 meq/L • Formula: • ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1) • What is the TBW? • How high will 1 liter of normal saline raise the plasma sodium? • Answer: • TBW is 30 L • Serum sodium will increase by approximately 1.4 meq/L for a total SNa of 111.4 meq/L

  16. Hyponatremia • Example: • a 90 kg man with a plasma sodium of 110 meq/L • Formula: • ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1) • What is the TBW? • How high will 1 liter of 3% saline raise the plasma sodium? • Answer: • TBW is 54 L • Serum sodium will increase by approximately 7.3 meq/L for a total SNa of 117.3 meq/L

  17. Hyponatremia hollywoodphony.files.wordpress.com • Example: • 63 y/o female at 75 Kg with N/V/D for 4 days • SNa is 108 mEq/L • She has had one seizure in the ambulance • Plasma osmolality is 251 mosmol/kg • Urine osmolality is 47 mosmol/kg • Uric acid is 6mg/dl • What type of hyponatremia does this patient have? • What additional labs/studies would you want?

  18. Hyponatremia • How will you Tx her? • Calculate the total body water • 0.5 x weight = 37.5 L • What rate of correction do you want? • 8 to 10 mEq/L in 6 to 8 hours • What fluid will you use? • 3% Saline • How will you calculate the amount of sodium to give her? • ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1) • How will her sodium increase after 1 liter of 3% saline? • By 10.8 mEq/L to 118.8 mEq/L

  19. Hyponatremia • What other medication will she need? • Lasix and a foley • Her sodium increases to 118.8 mEq/L over the next 8-10 hours. How will you continue to correct her hyponatremia? • ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1) • ΔSNa = 154mEq/L – 118.8mEq/L ÷ 38.5L = 0.9 mEq/L • So 2 liters of normal saline over the next 14 hours

  20. Hypernatremia

  21. HYPERNATREMIA • Hypernatremia is defined as a plasma Na+>145 meq/l • Hypernatremia represent hyperosmolality that results in water movement out of the cells into the extracellular fluid that causes cellular dehydration in the brain that is primarily responsible for the neurologic symptoms.

  22. Generation of hypernatremia • Water loss: hypernatremia due to water loss occurs only in patients who have hypodipsia, in adults with altered mental status, and in infants. • Na+ concentration > 150 is virtually never seen in an alert adult with a normal thirst mechanism and access to water.

  23. Hypernatremia Fluid volume status assessed by physical eaxam Hypovolemic Loss of H2O>Na+ loss Isovolemic Loss of H2O Hypervolemic Gain H2O and Na+ Check urine Na+ Check urine Na+ Check urine Na+ >20 mEq/L <10 mEq/L >20 mEq/L • Renal loss • Diuretic • Glycosuria • Renal failure • Extrarenal loss • GI-vomiting • GI-diarrhea • Excess • sweating • Respiratory loss • Renal loss • Diabetic insipidis • Central • Nephrogenic • Extrarenal loss • Insensible losses • Skin • Respiration • Iatrogenic • Hypertonic NaHCO3 • NaCl tablets • Hypertonic solutions • Mineralocorticoid • 1 Hyperaldosteronism • Cushing disease • Adrenal o • Hypertonicdialysis • Hemodilysis • Peritoneal dialysis • Treatment • Water replacement • D5W at 1-2 mEq/L/hr • ± vasopressin for • Central DI • Treatment • Saline then hypotonic • solution • Treatment • Diuretics ± dialysis

  24. Symptoms of hypernatremia • Lethargy ,weakness, irritability, are the earliest findings which can then progress to twitching ,seizures, coma, and death that are more related to cellular dehydration in the brain. • Patients with chronic hypernatremia may be relatively asymptomatic despite a plasma Na+ >170 • The severity of the neurologic symptoms is related to the both the degree and more importantly ,the rate of rise in the effective plasma osmolality.

  25. Treatment of hypernatremia • Rapid correction of hypernatremia can induce cerebral edema, seizures, permanent neurologic damage, and death therefore the plasma Na+ must be slowly lowered unless the patient has symptomatic hypernatremia.

  26. Treatment of hypernatremia…… • Water deficit= 0.4 LBW( plasma Na-140/ 140) • The maximum safe rate at which the plasma Na+ should be lowered (in the absence of hypernatremic symptoms) is 0.5 meq/L/h or 12 meq/L/per day

  27. CLINICAL USE Estimate the effect of 1 liter of any infusate on serum Na+ FORMULA* 1. Change in serum Na+ = 2. Change in serum Na+ = infusate Na+ - serum Na+ total body water + 1 (infusate Na+ + infusate K+) -serum Na+ total body water + 1 Estimate the effect of 1 liter of any infusate containing Na+ and K+ on serum Na+ Formula for Managing Hypernatremia

  28. Characteristics of Infusate

  29. Summary of Managing Hypernatremia • Isotonic saline unsuitable except in ECF volume depletion causing hemodynamic instability • Switch to hypotonic solutions as soon as circulatory status stabilized • Avoid excessive rapid correction or over correction • Select the most hypotonic infusate suitable with appropriate allowances for ongoing fluid losses • Most important - reassess infusion prescriptions at regular intervals based on pt’s clinical status and electrolyte values

  30. POTASSIUM

  31. POTASSIUM BALANCE • Potassium is the major intracellular cation that is essential for a variety of cellular and neuromuscular functions. • The total body K+ stores in a normal adult are 3000-4000 meq(50-55meq/kg) and the normal plasma concentration is 3.5-5 meq/l and inside cells is about 140 meq/l

  32. Regulation of potassium balance • The maintenance of K+ balance involves two functions: 1-the normal distribution of K+ between the cells and extra cellular fluid 2-the renal excretion of the K+ added to the extra cellular fluid from dietary intake and endogenous cellular breakdown

  33. Factors influencing the distribution of K+ between the cells and extra cellular fluid • Physiologic: 1-Na+k+ ATPase 2-catecholamines 3-insulin 4-plasma potassium concentration 5-exercise • Pathologic: 1-chronic disease 2-extra cellular PH 3-hyperosmolality

  34. Renal excretion of k+ • The urine is major route by which the K+ derived from diet and endogenous cellular breakdown , is eliminated from the body. • The primary event in urinary K+ excretion is the SECRETION of K+ from the tubular cell in to the lumen in the distal nephron.

  35. Renal Handling of K+ • Glomerulus: freely filtered • PCT, Thick As limb LOH : reabsorbed

  36. Hypokalemia

  37. Hypokalemia • Hypokalemia is defined as a K+ <3.5 meq/l, may result from one or more of the following: 1-decreased net intake 2-shift into the cells 3-increased net loss

  38. Hypokalemia • Exclude reredistribution • Alkalosis • Insulin • Periodic paralysis • Barium poisoning • Vitamin B12 therapy • Extrarenal K losses • Urine electrolytes • K+<20 mEq/day • Na+>100 mEq/day • (If Na+<100 mEq/day repeat • Test after increasing dietary • Na+>100 mEq/day) • Biliary losses • Lower GI losses • Fistula • Skin losses • Renal K losses • Urine electrolytes • K+>20 mEq/day • Na+>100 mEq/day High blood pressure Normal blood pressure Plasma renin levels Serum HCO3 -

  39. Plasma renin levels Serum HCO3 - • High plasma renin • Malignant HTN • Renovascular disease • Renin secreting tumor • Low HCO3 – • RTA Low plasma renin High HCO3 - Aldoserone Urine chloride • High • Hyperlado- • Steronism • Bilateral • hyperplasia • Low • Mineralocorticoid • Ingestion • Adrenal hyperpasia • (congenital) • Cushing syndrome • <10 mEq/day • Vomiting • <10 mEq/day • Bartter • Syndrome • Diuretics • Magnesium • deficiency T U T U

  40. Symptoms of hypokalemia • Marked symptoms are unusual unless the plasma K+ concentration is below 2.5-3 meq/l ,but in susceptible patients even mild reductions in the plasma potassium can predispose to potential fatal arrhythmia.

  41. Clinical Features • Mild hypokalemia : generally asymptomatic • Increased risk of mortality for pts with cardiovascular disease – trigger ventricular tachycardia / ventricular fibrillation (decrease K+ : d/t sympathetic stimulation) • Digitalis induced arrhythmias – can occur with normal drug levels if hypokalemia is present • Diuretic induced hypokalemia & hypomagnesemia must be avoided in pts on drugs that prolong QT interval : as it predisposes to polymorphic VT / Torsade de pointes • Hypokalemia < 3 mEq/L : Symptomatic

  42. Cardiac • Digitalis Intoxication : ventricular extrasystoles ventricular tachycardia ventricular fibrillation partial-complete AV block bradycardia atrial flutter atrial fibrillation • Ventricular arrhythmias : tachycardia / fibrillation

  43. Neuro-muscular • Fatigue • Myalgia • Muscular weakness involving lower limbs Severe Hypokalemia : • Paralysis ( extremities ) • Weakness of respiratory muscles ( dyspnea ) • Rhabdomyolysis (exercise induced)

  44. Gastro-intestinal • Constipation • Paralytic ileus

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