Micronutrient Requirements and Deficiencies

1. Micronutrient Requirements and Deficiencies Douglas L. Seidner, MD, FACG The Cleveland Clinic Digestive Disease Center

2. The ASPEN Nutrition Support Core Curriculum 2007

3. The ASPEN Nutrition Support Core Curriculum 2007

4. Composition of Body Fluids

6. Sodium (Na) • Total body Na is 40 mEq/kg (280 mEq in a 70 kg patient) • One third fixed in bone • Two thirds exchangeable (mostly extracellular) • Normal daily adult Na requirement is 1-2 mEq/kg • Renal Na reabsorption efficient (< 1mEq/L)

7. Sodium (Na) • Extracellular ion • Usual dose 100-150 mEq/d • This approximates 0.45%NS • Added as acetate or chloride salt Sodium Deficit = 0.6 x (wt in kg) x (140 – Na) + (140) x (Vol deficit in L)

8. Hyponatremia • Primary – due to sodium loss • Secondary – due to excess of free water (most common)

9. Primary Hyponatremia • GI losses • Fistula drainage • Use of diuretics • Adrenal insufficiency

10. Secondary Hyponatremia • Infusion of hypotonic solutions • Excess ingestion of free water • Increased reabsorption of free water (ADH)

11. Symptomatic Hyponatremia • Chronic hyponatremia usually asymptomatic until Na < 110-120 mEq/L • Acute hyponatremia can become symptomatic if Na < 120-130 mEq/L

12. Symptoms of Hyponatremia • Headaches • Confusion • Delirium • Seizures • Coma

13. Acute Hypotonic Hyponatremia (acute water intoxication <24hrs) • < 125 mEq/L – headache, apathy, nausea, confusion • < 115 mEq/L – seizures, coma

14. The ASPEN Nutrition Support Core Curriculum 2007

15. The ASPEN Nutrition Support Core Curriculum 2007

16. The ASPEN Nutrition Support Core Curriculum 2007

17. Estimating Sodium Requirement to Correct Serum Deficit • mEq of Na needed = (desired Na- measured serum Na) x .6 x body wt.(kg) • Give no more than ½ the first day • Rapid correction (>12mEq/day) can cause osmotic myelinolysis

18. HypernatremiaEtiology • Excessive water loss exceeds sodium loss or • Excesive sodium intake exceeds water intake

19. The ASPEN Nutrition Support Core Curriculum 2007

20. HypernatremiaSymptoms • Symptoms if Na>160 acutely or >170 chronically • Symptoms are neurologic lethargy and confusion, twitching, grand mal seizures, stupor and coma

21. Treatment of HypernatremiaCalculation of Water Deficit (70 kg man with a serum Na of 160mEq/L) • Water deficit (L) = 0.60 x wt in kg x [(serum Na/140) – 1] • Water deficit (L) = 0.60 x 70 x [(160/140) – 1] = 5.88 L

22. Potassium (K) • Intracellular cation • Usual dose is 60-120 mEq/d for PN patient • Added as acetate or chloride salt • Total body potassium falls ~370 mEq for each 1 mEq/L fall in measured serum K

23. Potassium (K) • Total body K is 50-55 mEq/kg • 98% is intracellular • Normal daily adult intake is 1 mEq/kg • Kidneys can decrease K excretion to no lower than 10 mEq/L

24. Potassium • Hypokalemia can cause weakness and if severe psychoses and paralysis • Hyperkalemia is more dangerous and can cause EKG changes, bradycardia, asystole, and vent. fib.

27. Guidelines for Potassium Therapy • For normal adults 40 – 60 mEq/day are given as IV replacement therapy • For K between 3.0 – 3.5mEq/L, 100 mEq will raise the serum K by 1 mEq/L • For K less than 3.0, 200 mEq will raise the serum K by 1 mEq/L • Do not exceed infusion rates of 20mEq/hour and recheck K after 40mEq

28. Hypokalemia and the ECG • Low voltage • Flattened or inverted T waves • Prominent U waves • Depressed ST segments • Widened QRS complex (K<2.0)

29. Hyperkalemia and the ECG • Flattenend P waves • Widened QRS complexes • Heart block, atrial asystole • Sine wave, V Fib

30. Electrocardiogram Hyperkalemia vs Acute MI Acute MI Hyperkalemia Hyperkalemia – T wave is tall, narrow and symmetrical Acute MI – T wave is tall but broad-based and asymmetrical

31. Treatment of Hyperkalemia • 10 units of Insulin + 25 gm of glucose • 45 mEq NaHCO3 • 25 gm cation exchange resin in 20% sorbitol solution orally q. 4-6 h or; • 50 gm cation exchange resin in 1-200 ml 35% sorbitol by enema q 4 h

32. CHLORIDE • Extracellular anion • Osmotic pressure and acid base balance • Chloride released as HCl as by-product of amino acid metabolism • Acetate salts used to prevent hyperchloremic acidosis • Administer as potassium or sodium salt Chloride deficit (mM) = 0.5 x body wt (kg) – (Cl-NORMAL _ Cl-MEASURED)

33. ACETATE • Amino acid metabolism may produce metabolic acidosis resulting in ↑ bicarbonate requirements • Bicarbonate changes pH; insoluble precipitate forms with calcium and magnesium (never add bicarbonate to PN solutions ) • Acetate salts are converted to bicarbonate in the liver • Functions as systemic alkalinizers • Use serum CO2 levels as a guide

34. CALCIUM • Extracellular cation • Usual dose 9-22 mEq/d • Calcium gluconate yields 4.65 mEq/gram Corrected calcium concentration: Total Ca2+CORRECTED(mg/dl) = Total Ca2+MEASURED(mg/dl) + ([4 – albumin (g/dl)] x 0.8) *ionized calcium level when in doubt

35. PHOSPHORUS • Intracellular anion • Usual dose 15-30 mM/d • 1 mEq potassium phosphate = 0.68 mM phosphate or 21 mg elemental phosphorus • 1 mEq sodium phosphate = 0.75 mM phosphate or 23 mg elemental phosphorus

36. MAGNESIUM • Cation (primarily intracellular) • Usual dose 8-24 mEq/d • Magnesium sulfate yields 8.12 mEq/gram Corrected magnesium concentration: Mg CORRECTED = Mg + 0.005[4.0-albumin (g/dl)]

37. Composition of Common Electrolyte Solutions

38. ELECTROLYTE REQUIREMENTS

39. Calcium 4.5-22 mEq Phosphate 15-30 mMol Magnesium 8-24 mEq Sodium 60-150 mEq Chloride 100-150 mEq Acetate 10-150 mEq/Liter Potassium 60-120 mEq Daily IV Electrolyte Recommendations

40. References • Langley G. “Fluid, Electrolyte, and Acid-Base Disorders.” In Gottschlich MM, DeLegge MH, Mattox T, Mueller C, Worthington, Eds. The ASPEN Nutrition Spport Core Curriculum: A Case-Based Approach-The Adult Patient. ASPEN, Silver Spring, MD, 2007, pp 104-128 • “Estimating Nutritional Requirements.” The Cleveland Clinic Foundation Nutrition Support Handbook, Eds Parekh N, DeChicco R. 2004 pp 34-60.

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