Presentation on theme: "PreWork This powerpoint will only be helpful if you run it as a slide show."— Presentation transcript:
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 H 2 SO 4 H 3 PO 4 HCl etc.
Getting Rid of Acid Bicarbonate Reabsorption by the Kidneys (Metabolic) Carbonic Anhydrase H 2 CO 3 Urine Blood HCO 3 - H+H+H+H+
The Lungs Eliminate CO2 (Respiratory) Getting Rid of Acid H 2 CO 3 HCO 3 - H+H+H+H+ H 2 O + CO 2 + Acidic Carbonic Acid
The Lungs Eliminate CO 2 (Respiratory) Getting Rid of Acid H 2 CO 3 HCO 3 - H+H+H+H+ H 2 O + CO 2 + AcidpH Carbonic Acid Alveoli
Salt rules volume Intracellular Extracellular H20H20 H20H20 Serum Sodium 140 mEq/L (Unchanged) Serum Sodium 140 mEq/L This represents normal sodium and volume. Extracellular space is the vascular plus tissue Note that intracelluar space is 2/3 of total body water Salt Rules Volume
Free Water Rules Serum Sodium Intracellular Extracellular Serum Sodium 125 mEq/L (hyponatremia) Serum Sodium 140 mEq/L This represents normal sodium and volume. Extracellular space is the vascular plus tissue Note that intracelluar space is 2/3 of total body water H20H20 H20H20 No Clinically Significant Volume Change (Water Spreads Out) H20H20 H20H20
The Challenge Figure out how the Renin- Angiotensin-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.
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 Ca 2+ [(4 – alb) x 0.8] + serum Ca 2+ Ex. Alb 2.3 Ca 2+ 7.6 Corrected calcium = [(4-2.3) x 0.8] + 7.6 = 8.96 mg/dL
Hypocalcemia Serum Ca 2+ < 8.5 mg/dL Pathophysiology Hypoparathyroidism Vitamin D deficiency Hypomagnesemia Hyperphosphatemia, 2 o hypoparathyroidism Medications/chelating agents Bisphosphonates, loop diuretics, calcitonin, phenytoin
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 Elemental Calcium Carbonate (Tums ®, OsCal ®, VIACTIV ® ) 40% Acetate (PhosLo ® ) used as a phosphate binder 25% Citrate (Citracal ® ) Important: Use when patient has little stomach acid (PPI) 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 Serum Ca 2+ > 10.5 mg/dL Pathophysiology 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
Hypophosphatemia Tx Mild – moderate PO 50-60 mmol/day divided in 3-4 doses o Neutra-Phos 1-2 packets QID mixed in 2.5 oz water or juice o K-Phos Neutral 1-2 tabs QID with water 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
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