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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
HCletc.
Getting Rid of Acid
Bicarbonate Reabsorption by the Kidneys (Metabolic)
Carbonic AnhydraseCarbonic Anhydrase HH22COCO33
UrineUrine
BloodBloodHCOHCO33
--
HH++
The Lungs Eliminate CO2 (Respiratory)
Getting Rid of Acid
HH22COCO33HCOHCO33-- HH++ HH22O + COO + CO22++
AcidicAcidicCarbonic AcidCarbonic Acid
The Lungs Eliminate CO2 (Respiratory)
Getting Rid of Acid
HH22COCO33HCOHCO33-- HH++ HH22O + COO + CO22++
AcidAcid
pHpH
Carbonic AcidCarbonic Acid
AlveoliAlveoli
NormalsArterial BloodpH:7.35-7.45pCO2: 40
PO2: 100
HCO3 25
NormalsVenous LytesSodium: 140Potassium: 4.5Chloride 100Total CO2 26
Total CO2
pCO2 =40mm Hg
40mm Hg EQUALS 1.2 mEq / L dissolved CO2
+ 25 mEq /L of HCO3
=26 mEq / L = Total CO2
Dissolved in Water…..
Click Here to Play That Again if you didn’t get it
Sodium and Water Prework
Volume and Tonicity
Salt rules volume
Intracellular IntracellularExtracellular
H20H2
0
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 IntracellularExtracellular
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
H20 H
20
No Clinically Significant Volume
Change
(Water Spreads Out)
H20H2
0
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.
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 serum calcium
Vitamin D serum calcium
Calcitonin 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/dLPathophysiology
Hypoparathyroidism Vitamin D deficiency Hypomagnesemia Hyperphosphatemia, 2o hypoparathyroidism Medications/chelating agents
Bisphosphonates, loop diuretics, calcitonin, phenytoin
Hypocalcemia
Clinical PresentationAcute
Fatigue, irritability, confusion, seizuresMuscle cramps, spasms, tetany
ChronicProlonged QT intervalBrittle nails, hair loss
Hypocalcemia Treatment
Always correct calcium for albumin!!Depends on acuity and severityCheck a magnesium level (find out
why for the exam! )Calcium supplementation
IV PO
IV Calcium
Acute symptomatic patientsCalcium 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 patientsCorrected symptomatic patients1-3 g/day of elemental calcium ±
vitamin DTake with meals, in divided doses for best absorption
PO Calcium
Calcium SaltElemental 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 levelsSymptomatic 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 Ca2+ > 10.5 mg/dLPathophysiology
Primary hyperparathyroidism**Malignancy**Other
High bone turnover, sarcoidosisMedications (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 Onset0.9% NS (plus furosemide below) * First line therapy
200-300 cc/hr 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 Serum Ca2+ q 6-12 hrs if symptomatic Serum Ca2+ daily if mild-moderate
Summary of Calcium
Calcium regulationPTH, Vitamin D, calcitoninCorrected calcium
Oral calcium productsTreatment of hypercalcemia
Phosphorus
Phosphorus
Normal value 2.7-4.5 mg/dLFunction
Phospholipid membraneSupports bone and teethMetabolism of nutrientsSource of ATP (energy, kinda critical)
Phosphorus
SourceMeats, dairy, eggs
RegulationKidney
Hypophosphatemia
Mild to Moderate 1-2 mg/dLSevere < 1 mg/dLPathophysiology
Decreased intake/absorptionVitamin D deficiency, phosphate binders
Increased excretionDiuretics, hyperparathyroidism
Intracellular shiftParenteral nutrition, insulin
Hypophosphatemia
Clinical PresentationNeuro – irritability, weakness,
seizuresMuscular – myalgiaHematologic – hemolysisPulmonary – respiratory distressOther – osteomalacia, arrhythmias
Hypophosphatemia Tx
Mild – moderate PO
50-60 mmol/day divided in 3-4 doseso Neutra-Phos 1-2 packets QID mixed in 2.5 oz
water or juiceo 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 IVRepeat 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*Typically used as laxative
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!*Oral agents
Hypophosphatemia
Monitoring IV therapy
Serum phosphorus every 6 hrs PO therapy
Serum phosphorus daily Renal function, BP (IV) Adverse events – diarrhea (PO), soft tissue
calcification, hypocalcemia, hypotension (IV)
Hyperphosphatemia
Serum phos > 4.5 mg/dLPathophysiology
Decreased urinary excretionRenal failure, hypoparathyroidism
Increased intakeParenteral nutrition, phosphate enemas
Extracellular shiftAcidosis
Hyperphosphatemia
Clinical PresentationN/V, muscle pain/weakness,
hyperreflexia, tetanySoft Tissue calcification
Due to calcium-phosphate productGoal is less than 55.
Hyperphosphatemia Tx
Restrict dairy productsPhosphate binders
Aluminum and magnesium-based antacidsNo longer first line, avoid in renal failure
Calcium (Drug of first choice unless Calcium is high)
SevelamerBinding resin Usually given with meals
Hyperphosphatemia
MonitoringSerum calcium levelSerum phosphorus level dailyRenal function
Summary of Phosphorus
IV vs. PO replacementGive IV phosphorus when severe
hypophosphatemiaMedications affecting serum
levelsPhosphate-binders, calcium,
diuretics, insulin, vitamin D