PreWork This powerpoint will only be helpful if you run it as a slide show. PreWork Objectives Understand the respiratory and metabolic mechanism for eliminating acid Know the normals for Arterial Blood Gasses and Venous Electrolytes Explain ADH and Aldosterone effects on sodium and water. Explain the effects of sodium and free water on volume and serum sodium Explain hormonal regulation of Ca++ and P04 Problem: Metabolism Produces Acid H2SO4 H3PO4 HCl etc. Getting Rid of Acid Bicarbonate Reabsorption by the Kidneys (Metabolic) Blood Carbonic Anhydrase HCO3- H2CO3 Urine H+ Getting Rid of Acid The Lungs Eliminate CO2 (Respiratory) HCO3- + H+ Acidic H2CO3 Carbonic Acid H2O + CO2 Getting Rid of Acid The Lungs Eliminate CO2 (Respiratory) HCO3Acid + H+ H2CO3 H2O + CO2 Carbonic Acid pH Alveoli Normals Arterial Blood pH: 7.35-7.45 pCO2: 40 PO2: 100 HCO3 25 Normals Venous Lytes Sodium: 140 Potassium: 4.5 Chloride 100 Total CO2 26 Total CO2 pCO2 =40mm Hg Dissolved in/ L Water ….. 40mm 1.2 HgmEq EQUALS dissolved + CO2 25 mEq /L of HCO3 =26 mEq / L = Total CO2 Click Here to Play That Again if you didn’t get it Sodium and Water Prework Volume and Tonicity Salt rules volume Salt Rules Volume This represents normal sodium and volume. Extracellular space is the vascular plus tissue Note that intracelluar space is 2/3 of total body water Intracellular Serum Sodium 140 mEq/L (Unchanged) Serum Sodium 140 mEq/L Extracellular Intracellular Free Water Rules Serum Sodium This represents normal sodium and volume. Extracellular space is the vascular plus tissue Note that intracelluar space is 2/3 of total body water Intracellular Serum Serum Sodium Sodium 125 mEq/L 140 mEq/L (hyponatremia) Extracellular No Clinically Significant Volume Change (Water Spreads Out) Intracellular The Challenge Figure out how the ReninAngiotensin-Aldosterone system and how ADH relate to the above examples of sodium and water. What turns them on and what turns them off. Calcium And Phosphate Prework Prework questions on Calcium and Phosphate will be easy. Exam questions will be slightly less easy. Calcium Calcium Normal value: Total: 8.5–10.5 mg/dL (2.1–2.7 mmol/L) Ionized (free): 4.6–5.2 mg/dL (1.15–1.38 mmol/L) Function Bone and teeth Neuromuscular activity (SA node, AV node) Endocrine/exocrine function Platelet function Muscle cell contraction Calcium Regulation PTH Vitamin D serum calcium Calcitonin serum calcium serum calcium Calcium homeostasis figure (next slide) http://www.biol.andrews.edu/fb/spring/Chap.45-%20Endocrinology/4510.jpg Corrected Calcium Only ionized (unbound) calcium is active Calcium must be corrected when there is a low albumin (a larger percent is ionized) For each 1mg/dl change in albumin from normal, 0.8mg/dl change in Ca2+ [(4 – alb) x 0.8] + serum Ca2+ Ex. Alb 2.3 Ca2+ 7.6 Corrected calcium = [(4-2.3) x 0.8] + 7.6 = 8.96 mg/dL Hypocalcemia Serum Ca2+ < 8.5 mg/dL Pathophysiology Hypoparathyroidism Vitamin D deficiency Hypomagnesemia o Hyperphosphatemia, 2 hypoparathyroidism Medications/chelating agents Bisphosphonates, phenytoin loop diuretics, calcitonin, Hypocalcemia Clinical Presentation Acute Fatigue, irritability, confusion, seizures Muscle cramps, spasms, tetany Chronic Prolonged QT interval Brittle nails, hair loss Hypocalcemia Treatment Always correct calcium for albumin!! Depends on acuity and severity Check a magnesium level (find out why for the exam! ) Calcium supplementation IV PO IV Calcium Acute symptomatic patients Calcium chloride 1 gm IV (27% elemental) Very irritating to veins Calcium gluconate 2-3 gm IV (9% elemental) availability in liver disease PO Calcium Chronic asymptomatic patients Corrected symptomatic patients 1-3 g/day of elemental calcium ± vitamin D Take with meals, in divided doses for best absorption PO Calcium Calcium Salt Carbonate (Tums®, OsCal®, VIACTIV®) Acetate (PhosLo®) used as a phosphate binder Citrate (Citracal®) Important: Use when patient has little stomach acid (PPI) Elemental Calcium 40% 25% 21% Hypocalcemia Monitoring Albumin, magnesium levels Symptomatic patient Serum and ionized calcium levels every 4-6 hrs after IV calcium Serum calcium every 24-48 hrs during oral therapy, then 1-2 times weekly Hypercalcemia Ca2+ > 10.5 mg/dL Pathophysiology Serum Primary hyperparathyroidism** Malignancy** Other High bone turnover, sarcoidosis Medications (thiazides, lithium, vitamin D) Hypercalcemia Clinical Presentation Depends on degree and onset GI – N/V, anorexia, constipation CV – short QT, prolonged PR & QRS Neuro – fatigue, weakness, confusion Renal – polyuria, nocturia, nephrolithiasis Hypercalcemia Treatment Drug Dose Onset 0.9% NS (plus 200-300 cc/hr furosemide below) * First line therapy 24-48 hrs Furosemide 40-80 mg IV q 1-4 hrs Upon diuresis Calcitonin 4 units/kg SC or IM q 12 hrs 1-2 hrs Bisphosphonates Pamidronate 30-90 mg IV over 2-24 hrs 1-2 days Prednisone 40-60 mg/day 1-2 weeks Hypercalcemia Treatment Other treatment options Gallium nitrate, mithramycin Monitoring Albumin ECG Ca2+ q 6-12 hrs if symptomatic Serum Ca2+ daily if mild-moderate Serum Summary of Calcium Calcium regulation PTH, Vitamin D, calcitonin Corrected calcium Oral calcium products Treatment of hypercalcemia Phosphorus Phosphorus Normal value 2.7-4.5 mg/dL Function Phospholipid membrane Supports bone and teeth Metabolism of nutrients Source of ATP (energy, kinda critical) Phosphorus Source Meats, dairy, eggs Regulation Kidney Hypophosphatemia Mild to Moderate 1-2 mg/dL Severe < 1 mg/dL Pathophysiology Decreased Vitamin intake/absorption D deficiency, phosphate binders Increased Diuretics, excretion hyperparathyroidism Intracellular Parenteral shift nutrition, insulin Hypophosphatemia Clinical Presentation – irritability, weakness, seizures Muscular – myalgia Hematologic – hemolysis Pulmonary – respiratory distress Other – osteomalacia, arrhythmias Neuro Hypophosphatemia Tx Mild – moderate PO 50-60 mmol/day divided in 3-4 doses Neutra-Phos 1-2 packets QID mixed in 2.5 oz water or juice o K-Phos Neutral 1-2 tabs QID with water o NOTE: Dose in mmol NOT mEq Hypophosphatemia Tx Mild – moderate IV 0.08-0.15 mmol/kg IV Repeat until serum phosphorus > 2 mg/dL Hypophosphatemia Tx Severe IV 0.25-0.5 mmol/kg IV Repeat until serum phosphorus > 2 mg/dL Phosphorus Replacement Product Phos Content Na Content K Content K-Phos Neutral* 250mg 8 mmol 13 mEq 1.1 mEq Fleet Phospho-soda* 20 mmol 24 mEq 0 Sodium Phosphate 3 mmol/mL 4 mEq/mL 0 K-Phos Original Dissolving Tablets 3.6 0 3.7mEq Neutra-Phos* 250mg Recently discontinued Doesn’t matter! Neutra-Phos K* 250mg Recently discontinued Doesn’t matter! Typically used as laxative *Oral agents Hypophosphatemia Monitoring IV therapy Serum PO phosphorus every 6 hrs therapy Serum Renal phosphorus daily function, BP (IV) Adverse events – diarrhea (PO), soft tissue calcification, hypocalcemia, hypotension (IV) Hyperphosphatemia Serum phos > 4.5 mg/dL Pathophysiology Decreased Renal urinary excretion failure, hypoparathyroidism Increased intake Parenteral nutrition, phosphate enemas Extracellular Acidosis shift Hyperphosphatemia Clinical Presentation N/V, muscle pain/weakness, hyperreflexia, tetany Soft Tissue calcification Due to calcium-phosphate product Goal is less than 55. Hyperphosphatemia Tx Restrict dairy products Phosphate binders Aluminum and magnesium-based antacids No longer first line, avoid in renal failure Calcium (Drug of first choice unless Calcium is high) Sevelamer Binding resin Usually given with meals Hyperphosphatemia Monitoring Serum calcium level Serum phosphorus level daily Renal function Summary of Phosphorus IV vs. PO replacement Give IV phosphorus when severe hypophosphatemia Medications affecting serum levels Phosphate-binders, calcium, diuretics, insulin, vitamin D